bluuebunny/crossref_metadata_2025 huggingface dataset:
The Matching of Diesel Engine to Exhaust Turbocharger—Improved Calculation Model at T-Junction
Authors: Morimune T. , Hirayama N.
Published: October 2009

The suitability of the analysis of the unsteady flow through the exhaust junction plays an important role in developing a computer program for matching a diesel engine to an exhaust turbocharger. This paper describes an improvement of the calculation procedure for computing the behavior of the unsteady gas flow at the exhaust junction. Measured values of pressure, temperature, and mass flow rate are compared with computer predictions using four different pipe junction computations: constant pressure model, momentum model, simplified model, and the improved exact model developed in this study. This comparison shows that the new technique gives the best agreement with the measured values, while the computer time required is twice as long. Under unsteady flow conditions the exhaust junction gives six types of flow configuration, and calculations indicate that only some of these types of flow dominate; the rest occur for only short intervals.
Flow Field Surveys at the Rotor Inlet of a Radial Inflow Turbine
Authors: Miller E. C. , L’Ecuyer M. R. , Benisek E. F.
Published: October 2009

Experiments were performed using a five-port cobra probe to survey the flow field at the rotor inlet of a 110-mm-dia turbocharger radial inflow turbine wheel. The turbine housing was modified to accommodate a probe insert to position the probe tip 4.1 mm above the rotor tip while preserving the internal contour of the production turbine housing. The cobra probe was traversed axially and circumferentially to determine the rotor inlet flow properties while the turbine was operated at design flow conditions with a reduced turbine inlet temperature. Measurements were made with the probe tip in the near-nulled position to determine the local values of total pressure, static pressure, velocity, and flow angle as functions of Z and θ. Results are presented showing the distribution of the housing total pressure loss coefficient, the rotor inlet mass flux, and the rotor inlet tangential velocity. In addition, values for rotor inlet mass average properties are given.
The Influence of Torsional-Lateral Coupling on the Stability Behavior of Geared Rotor Systems
Authors: Schwibinger P. , Nordmann R.
Published: October 2009

In high-performance turbomachinery trouble often arises due to unstable asynchronous lateral vibrations. The instabilities are mostly caused by oil film bearings, clearance excitation, internal damping, annular pressure seals in pumps, or labyrinth seals in turbocompressors. In recent times as an additional influence the coupling between torsional and lateral vibrations is considered, which is of practical importance in geared rotor systems. In the literature [1, 2], some field problems are described, where in geared drive trains unstable lateral vibrations occurred together with torsional oscillations. This presentation studies the influence of torsional-lateral coupling on the stability behavior of a simple geared system supported by oil film bearings. The coupling effect is investigated by parameter studies and a sensitivity analysis for the uncoupled and the coupled system.
The Effect of Anisotropic Support on Rotor Instability Due to Fluid Leakage
Authors: Wang Jhy-Horng , Tsai Ming-Te
Published: October 2009

The instability caused by fluid leakage leads to limited performance in turbomachines. This instability may be improved by using flexible bearing supports with anisotropic stiffness. With a simplified model this effect is investigated, including the influence of many parameters. The results show that the optimum range of anistropy is strongly dependent on the parameters of the rotor-bearing system. In this paper an explanation from an energy point of view is presented to clarify the different stability behaviors with anisotropic bearing support.
A New Approach to Evaluating the In-Service Performance of Marine Gas Turbine Air Filters
Authors: Hobday J. S. , Havill J.
Published: October 2009

Early work by the Naval Engineering Department of NGTE Pyestock, now RAE Pyestock, sought to define the Marine Aerosol through simple relationships between wind speed and aerosol size and distribution. Experience has shown the resulting Standard Aerosols to be unrepresentative of the actual conditions found in service. This paper describes a new approach using available ship and meteorological data and proven analytical techniques to generate a multivariable mathematical model of the Marine Aerosol embracing a wide envelope of operating conditions. It further describes how a simple model of a gas turbine air filter can be used in conjunction with the Marine Aerosol model and a model describing a ship propulsion system to predict the performance of the filter in terms of probable salt ingestion by the ship’s engines. This versatile design tool can be used for direct or comparative assessments of separator applications for marine gas tubine propulsion engines and generating sets.
Analytical and Experimental Investigation of Two-Phase Flow Screw Expanders for Power Generation
Authors: Taniguchi H. , Kudo K. , Giedt W. H. , Park I. , Kumazawa S.
Published: October 2009

An analytical procedure for calculating the performance of a two-phase flow screw-type expander is presented. Predicted results are compared with experimental measurements made with a recently developed prototype expander. This expander was designed for investigating the applicability of this type of machine as the expansion device in refrigeration or heat pump cycles with the objective of taking advantage of the power-producing capability of the expanding fluid. It has two rotors each with a diameter of 81.6 mm and a length of 135 mm, and was operated with Freon-12 entering at a pressure of 1.588 MPa (230.4 psia) and subcooling of between 2 and 12 K. Maximum power generated was 10 kW at a rotor speed of 3000 rpm. The internal (machine) efficiency is predicted to increase from about 30 to 70 percent as the rotor speed increases from 500 to 3000 rpm. Experimental results over this same speed range increase from 30 to 60 percent. The lower experimental values at the higher rotor speeds are attributed primarily to frictional losses not included in the analysis. Estimates of the performance of machines with larger diameter rotors yielded internal efficiencies reaching 80 percent and increases in power output proportional to the square of the rotor diameter.
An Example of the Manipulation of Effective Vapor Pressure Curves by Thermodynamic Cycles
Authors: Radermacher R.
Published: October 2009

The performance of a two-stage Rankine cycle employing a working fluid mixture and solution circuits has been computed with reference to heat pump applications. Its performance is compared to the single-stage version of this cycle and one operating with pure refrigerants. It is found that the two-stage cycle operates along an “effective” vapor pressure curve of very flat slope, resulting in pressure ratios that are reduced to about one third compared to conventional cycles. For large temperature differences between heat sink and source the Coefficient of Performance (COP) can be increased by up to 50 percent.
Model of TPTC Stirling Engine With Adiabatic Working Spaces
Authors: Renfroe D. A. , Counts M.
Published: October 2009

A Stirling engine incorporating a phase-changing component of the working fluid has been modeled with the assumption that the compression and expansion space are adiabatic, and that the heat exchanger consists of a cooler, regenerator, and heater of finite size where the fluid follows an idealized temperature profile. Differential equations for the rate of change of mass in any cell and pressure over the entire engine were derived from the energy, continuity, state equations, and Dalton’s law. From the simultaneous solution of these equations, all of the information necessary for calculation of power output and efficiency were obtained. Comparison of the results from this model with previous studies shows that the advantage of adding a phase-changing component to the working fluid may have been overstated.
Full-Engine Field Test: An Approach to Improve the Gas Turbine Combustion System
Authors: Gianola M.
Published: October 2009

For purposes of both final verification and optimization of TG 20 and TG 50 combustion systems, test programs have been carried out directly on full engines operating in the field, as well as in the test bench. These programs were carried out in two separate phases: the first one directed to determine the behavior at load by means of experimental data acquisition, including temperature distribution on the combustor exit plane for different burner arrangements, and the second one directed to optimize the ignition process and the acceleration sequence. This paper, after a brief description of the instrumentation used for each test, reports the most significant results burning both fuel oil and natural gas. Moreover, some peculiar operational problems are mentioned, along with their diagnosis and the corrections applied to the combustion system to solve them.
Measurement of Temperature and Velocity Vectors in a Combusting Environment Using Low-Cost Probes
Authors: Khalil M. B. , Plett E. G.
Published: October 2009

Radial traverses were made to measure temperature distributions and velocity vectors in an atmospheric pressure test combustor burning gaseous fuels with heating values in the low-medium range. Temperature was measured using an aspirated pyrometer probe. Velocity vectors were determined from measurements of a five-hole probe (a two-hole probe was used prior to the five-hole probe to determine whether the flow was directed upstream or downstream). The measuring traverse was carried out across the entire diameter at ten sections along the combustor (which was specially designed to allow in insertion of probes at the ten axial sections, through three holes at 120 deg from each other around the circumference). These measurements were repeated for ten runs that incorporated a variety of operating conditions of the combustor. Temperature measurements were validated by application of the first law of thermodynamics. Velocities were validated using the principles of conservation of mass and angular momentum. The analysis showed that temperatures can be measured to within 10°C in a combusting environment of gaseous fuels for which the temperature is in the vicinity of 1500 K, by an aspirated pyrometer. The axial velocity component can be measured to an average accuracy of 7.6 percent using five-hole probes. The radial component of velocity can be obtained within ± 5 percent in most of the combustion space. The accuracy of measuring the circumferential velocity component could not be validated, partly because it was extremely small. Also, in order to validate it, some independent means of establishing its origin is needed. In this case, due to the lack of precision in fabricating the combustor and the holes for air admission, as well as due to the extremely small value of this component in the present study, it was not possible to establish the reliability of the measured values. The study recommends the use of aspirated pyrometers and five-hole probes in a combusting environment, provided that the yaw angle does not exceed 60 deg and the three components of velocity have comparable magnitudes. The probes should be made as small as possible and frequent purging should be practiced in their operation to avoid errors due to blockage of probes’ passages by water or dust particles. These probes were chosen for this application because of the ease with which they can be used, as well as for cost considerations.
Methods for Achieving a Combustion-Driven Pressure Gain in Gas Turbines
Authors: Kentfield J. A. C. , O’Blenes M.
Published: October 2009

The objective of the work was to compare on both an ideal and, where possible, an actual basis the approximate performances of four types of pressure-gain combustor. Such combustors are potentially suitable for use in gas turbines in place of conventional steady-flow combustors. The ideal theoretical performance comparison was based on a specially conceived, universal, analytical model capable of representing, in a fundamental manner, the dominant features of each of the systems studied. The comparisons of nonideal performance were based on actual test results and, where these were not available, on ideal performance characteristics suitably modified to take irreversibilities, etc., into account. It was found that in general the pressure-gain potential of the concepts studied increased with increasing system complexity. It was also found that with most concepts the combustor pressure ratio achievable increases with combustor temperature ratio.
Advanced High-Temperature Instrumentation for Hot Section Research Applications
Authors: Englund D. R. , Seasholtz R. G.
Published: October 2009

Programs to develop research instrumentation for use in turbine engine hot sections are described. These programs were initiated to provide improved measurement capability as support for a multidisciplinary effort to establish technology leading to improved hot section durability. Specific measurement systems described here include heat flux sensors, a dynamic gas temperature measuring system, laser anemometry for hot section applications, an optical system for viewing the interior of a combustor during operation, thin film sensors for surface temperature and strain measurements, and high-temperature strain measuring systems. The paper will describe the state of development of these sensors and measuring systems and, in some cases, will show examples of measurements made with this instrumentation. The paper covers work done at the NASA Lewis Research Center and at various contract and grant facilities.
NNEPEQ—Chemical Equilibrium Version of the Navy/NASA Engine Program
Authors: Fishbach L. H. , Gordon S.
Published: October 2009

The Navy NASA Engine Program, NNEP, developed in 1975, currently is in use at a large number of government agencies, commercial companies, and universities. This computer code has been used extensively to calculate the design and off-design (matched) performance of a broad range of turbine engines, ranging from subsonic turboprops to variable cycle engines for supersonic transports. Recently, there has been increased interest in applications that NNEP was not capable of simulating, namely, high Mach applications, alternate fuels including cryogenics, and cycles such as the gas generator air-turbo-rocket (ATR). In addition, there is interest in cycles employing ejectors such as for military fighters. New engine component models had to be created for incorporation into NNEP, and it was also found necessary to include chemical dissociation effects of high-temperature gases. This paper discusses the incorporation of these extended capabilities of NNEP and illustrates some of the effects of these changes.
Combustor and Seal System for a Water Piston Propulsor
Authors: LeCren R. T. , Gildersleeve R. E. , Swanek R. A.
Published: October 2009

The Water Piston Propulsor (WPP) is an advanced in-water propulsion system for Marine Corps amphibious vehicles. Significant weight and volume reductions are the primary advantages of the WPP system versus the more conventional propulsion technologies used today. WPP thrust is produced by porting high-pressure combustion gases into the water-filled channels of a rotor. Gas expansion results in the expulsion of water from the downstream end of the rotor channel. Solar Turbines Incorporated, a subsidiary of Caterpillar Inc., is currently under contract to the David Taylor Research Center for the development of the high-temperature, high-pressure combustor and rotor seal systems. Details of combustor and rotor seal design, performance, and development test are discussed.
An Experimental Data Base for the Computational Fluid Dynamics of Combustors
Authors: Charles R. E. , Samuelsen G. S.
Published: October 2009

A model axisymmetric gas-fired can combustor is used to (1) establish the sensitivity of the aerodynamic and thermal structure to inlet boundary conditions, and (2) thereby establish a demanding and comprehensive data base for the computational fluid dynamics of combustors. The parameters varied include fuel injection angle and inlet configuration. Detailed characterizations of the aerodynamic and thermal flowfields are accomplished using two-color laser anemometry and a Type R thermocouple, respectively. Specific results show that the reactor operation is especially sensitive to modest changes in both the inlet geometry and fuel injection angle. For example, the addition of a step expansion significantly alters the size and location of the swirl-induced toroidal recirculation zone. Further, the use of the step expansion, in combination with the injection of fuel matched to the swirl aerodynamics, transforms the recirculation zone to an on-axis structure. The addition of a divergent inlet further enhances the effectiveness of the backmixing by enlarging the recirculation zone. The data base developed for these conditions is carefully documented and provides a comprehensive challenge for the computational fluid dynamics of combustors.
Multivariate Turbofan Engine Control for Full Flight Envelope Operation
Authors: Polley J. A. , Adibhatla S. , Hoffman P. J.
Published: October 2009

The design of a full flight envelope nonlinear multivariable controller is described for a single-bypass variable-cycle jet engine. The nonlinear controller is obtained by using appropriate engine corrected parameters to schedule multivariable linear compensator gains designed at selected operating points of the flight envelope. The KQ (K-matrix compensator, Q-desired response) multivariable control design technique is used to design the compensators using linear state-space models obtained from a detailed nonlinear aerothermo model. The controller is implemented in the detailed nonlinear aerothermo model. The paper describes an example KQ compensator design, the corrected-parameter gain scheduling approach, and controller performance validation by nonlinear simulation. Computer simulations for sea-level static, and supersonic operating points are included to show the closed-loop transient performance in the presence of an acceleration fuel schedule.
AGT101/ATTAP Ceramic Technology Development
Authors: Boyd G. L. , Kreiner D. M.
Published: October 2009

The Garrett Turbine Engine Company/Ford Advanced Gas Turbine Program, designated AGT101, came to an end in June 1987. During this ceramic technology program, ceramic components were exposed to over 250 h of engine test. The 85-h test of the all-ceramic hot section to 1204C (2200F) was a significant accomplishment. However, this AGT101 test program also identified ceramic technology challenges that require continued development. These technology challenges are the basis for the five-year Advanced Turbine Technology Applications Project (ATTAP), which began in Aug. 1987. The objectives of this program include: (1) further development of analytical tools for ceramic component design utilizing the evolving ceramic material properties data base; (2) establishment of improved processes for fabricating advanced ceramic components; (3) development of improved procedures for testing ceramic components and test verification of design methods; and (4) evaluation of ceramic component reliability and durability in an engine environment. These activities are necessary to demonstrate that structural ceramic technology has the potential for competitive automotive engine life cycle cost and life.
Microstructural Effects on Fracture Toughness of Polycrystalline Ceramics in Combined Mode I and Mode II Loading
Authors: Singh D. , Shetty D. K.
Published: October 2009

Fracture toughness of polycrystalline alumina and ceria partially stabilized tetragonal zirconia (CeO2-TZP) ceramics were assessed in combined mode I and mode II loading using precracked disk specimens in diametral compression. Stress states ranging from pure mode I, combined mode I and mode II, and pure mode II were obtained by aligning the center crack at specific angles relative to the loading diameter. The resulting mixed-mode fracture toughness envelope showed significant deviation to higher fracture toughness in mode II relative to the predictions of the linear elastic fracture mechanics theory. Critical comparison with corresponding results on soda-lime glass and fracture surface observations showed that crack surface resistance arising from grain interlocking and abrasion were the main sources of the increased fracture toughness in mode II loading of the polycrystalline ceramics. The normalized fracture toughness for pure mode II loading, (KII/KIc), increased with increasing grain size for the CeO2-TZP ceramics. Quantitative fractography confirmed an increased percentage of transgranular fracture of the grains in mode II loading.
Thin-Filament Pyrometry: A Novel Thermometry Technique for Combusting Flows
Authors: Goss L. P. , Vilimpoc V. , Sarka B. , Lynn W. F.
Published: October 2009

A novel technique is described for making temperature measurements in a combusting flow. The technique, Thin-Filament Pyrometry, is based on the blackbody emission of a small ceramic filament (15 μm), which is introduced into the flow field under study. Because the emission along the entire length of the filament is recorded, the complete spatial temperature distribution is measured. The temporal response of the filament is ∼ 700 Hz under ambient conditions. To demonstrate the capabilities of the technique in a combusting flow, a H2-N2 jet diffusion flame was studied. The evolution of the large-scale buoyancy-driven structures at low Reynolds numbers was followed by this technique.
Spray Characteristics of a Spill-Return Airblast Atomizer
Authors: Dai X. F. , Lefebvre A. H. , Rollbuhler J.
Published: October 2009

The spray characteristics of a spill-return airblast atomizer are examined using water as the working fluid. Measurements of mean drop size, drop size distribution, spray cone angle, and circumferential liquid distribution are carried out over wide ranges of liquid injection pressures and atomizing air velocities. Generally it is found that an increase in nozzle bypass ratio worsens the atomization quality and widens the spray cone angle. Increase in airblast air velocity may improve or impair atomization quality depending on whether it increases or decreases the relative velocity between the liquid and the surrounding air. Airblast air can also be used to modify the change in spray cone angle that normally accompanies a change in bypass ratio.
Flow in Liner Holes for Countercurrent Combustion Systems
Authors: Abuaf N. , Rasmussen N. S. , Szema L. C.
Published: October 2009

Heavy-duty gas turbine combustion systems have a “reverse flow” combustion-cooling air network. High-temperature gradients have been observed in some combustion liners around the plain holes, or around the cylindrical inserts welded into the mixing holes. Flow visualization tests were performed in a countercurrent flow facility. Measurements of pressure and velocity distributions in and around the mixing hole jet were taken, and mass flow rates and discharge coefficients were calculated in order to characterize and compare the two geometries. The results with a plain hole (square-edged orifice) and the cylindrical insert show the presence of a sharp separation region at the trailing edge (combustion side) of the liner hole, which may cause the high-temperature gradients observed under operating conditions. The measured discharge coefficients show a dependence on the insert geometry, the flow parameter (K), and the bottom section (combustion side) countercurrent flow velocity.
A Methanol/Oxygen Burning Combustor for an Aircraft Auxiliary Emergency Power Unit
Authors: Carr E. , Todd H.
Published: October 2009

The development of advanced single-engine aircraft with reduced stability and “Fly-by-Wire” control systems requires the provision of emergency hydraulic and electrical power from a stored energy system. The desire to achieve this objective using readily available fluids of low toxicity has led to the development of a methanol/oxygen burning combustor to provide a hot gas stream to drive a small turbine. The paper describes the performance of a 300 kW output combustor, which is cooled by the methanol consumed.
World’s First Full STIG™ LM5000 Installed at Simpson Paper Company
Authors: Kolp D. A. , Moeller D. J.
Published: October 2009

In early 1988, Simpson Paper Company installed the world’s first GE LM5000 cogeneration plant with full high and low pressure steam injection. The full STIG LM5000 achieves a dramatic power increase (from 32.5 MW to 49.5 MW) and remarkable improvements in efficiency from 36 to 43 percent, while reducing NOx emissions from 225 to less than 25 ppmv before further reduction with SCR. The plant, installed at Ripon, CA, features: (1) 130,000 lb/hr (59,000 kg/h) of steam injection at three locations on the gas turbine; (2) the first-time use of SCR with the STIG LM5000 resulting in an ultimate NOx emission rate of 6-13 ppmv; (3) a unique feedwater heat exchanger arrangement to reduce boiler stack temperature to 250°F (121°C); and (4) an innovative submicron inlet air filtration system to minimize the need for compressor washing. The details of cycle selection, design, installation, performance, and economic benefits of this first full STIG installation provide a useful insight into the potential of a flexible new technology.
Gas Turbine Reliability: How? How Much? Where?
Authors: Lenz H. D. , Hill H. W.
Published: October 2009

Methods to establish component reliability have been in existence for nearly forty years. However, these methods have not been applied to gas turbine systems, because of a lack of consistent definitions and methodology. This paper describes a systematic procedure for calculating control-system reliability, which also can be extended to calculations for mechanical equipment. This is accomplished by a computerized model. Using the results of this model, practical methods and configurations are described to improve gas turbine reliability, such as: redundancy of essential components; quality of components; environmental factors; sensing devices and actuators; and circuits and logic design. The paper also compares these methods and the resulting reliability improvements in system cost and complexity.
Assessment of Gas Turbine Vibration Monitoring
Authors: Lifson A. , Quentin G. H. , Smalley A. J. , Knauf C. L.
Published: October 2009

This paper presents a basis for selecting and justifying vibration monitoring equipment for power-generating gas turbines. Users of industrial gas turbines from utility and petrochemical companies are surveyed; a utility forced outage data base is analyzed; typical vibration limits are presented; and the current capabilities of commercial monitoring systems and vibration transducers are summarized. The industry survey by site visits and questionnaire develops common trends; it itemizes malfunctions that can be successfully identified with appropriate vibration monitoring; it summarizes current practices, benefits, limitations, and operating experience with various transducer types, as applied to harsh gas turbine environments. Vibration limits, trending, and sources of vibration are addressed. Operational factors are considered in planning and cost justifying vibration monitoring systems for a basic trip protection, periodic measurements, and on-line computerized continuous protection. Seventeen case histories and examples illustrate and support these findings. Analysis of the utility-generated data base complements the industry survey; it isolates the contribution of different vibration-related outages for base loaded and peaking units; graphic results break down these outages into duration, man-hours to repair, and frequency of occurrence.
Structural Analysis Method Development for Turbine Hot Section Components
Authors: Thompson R. L.
Published: October 2009

This paper summarizes the structural analysis technologies and activities of the NASA Lewis Research Center’s gas turbine engine Hot Section Technology (HOST) program. The technologies synergistically developed and validated include: time-varying thermal/mechanical load models; component-specific automated geometric modeling and solution strategy capabilities; advanced inelastic analysis methods; inelastic constitutive models; high-temperature experimental techniques and experiments; and nonlinear structural analysis codes. Features of the program that incorporate the new technologies and their application to hot section component analysis and design are described. Improved and, in some cases, first-time three-dimensional nonlinear structural analyses of hot section components of isotropic and anisotropic nickel-base superalloys are presented.
Investigation of Swirler/Dilution Jet Flow Split on Primary Zone Flow Patterns in a Water Model Can-Type Combustor
Authors: Koutmos P. , McGuirk J. J.
Published: October 2009

LDA measurements of the three mean velocity components and the corresponding turbulence intensities have been made to provide qualitative and quantitative information on the flow field in a water model of a can-type gas turbine combustion chamber. The combustor geometry comprised a swirl-driven primary zone, annulus-fed rows of primary and secondary jets, and an exit contraction. The effect of variation of the flow split between the swirler and the dilution holes on the flow pattern in the primary zone has been investigated in detail. Flow visualization studies revealed that significant changes occur in this region due to the interaction between the swirling flow and the radially directed primary jets. A large toroidal recirculation was formed and high levels of turbulence energy were generated in the core of the combustor at low levels of swirler flow rate. As the swirl level increases, the strength of this recirculation was observed to weaken. Beyond a critical level, the primary recirculation was pushed off center and the undesirable feature of a forward velocity on the combustor axis in the primary zone was observed. Despite the dramatic changes brought about in the primary zone, the flow pattern downstream of the secondary jets was practically the same for all flow splits due to the strong mixing caused by the two rows of jets.
Low-Emission Diesel Fuel for 1991–1994
Authors: Springer K. J.
Published: October 2009

A low-emission diesel fuel (LEDF) is proposed as a way to help the HD diesel engine manufacturer meet stringent U.S. particulate limits beginning in 1991. A new LEDF fuel specification would include sulfur reduction to less than 0.05 percent and a new specification putting a cap or maximum on aromatic content. Additive treatment to control injector deposits for less engine deterioration with time and a combustion improver could also be helpful. A two-fuel strategy would permit orderly phase-in of LEDF. As with unleaded gasoline, a smaller filler neck and nozzle and separate storage tank for dispensing would be required. Unlike the sale of unleaded fuel, the prices of DF-2 and LEDF must be equalized to prevent fuel switching.
Current Regulations Impacting Exhaust Emissions From Stationary Internal Combustion Engines
Authors: Hall D. W.
Published: October 2009

The San Francisco Bay Area is in a nonattainment area for both ozone and carbon monoxide. A significant amount of air pollution emanates from the combustion of fuels in stationary internal combustion engines. The NOx emissions output from stationary I.C. engines in the Bay Area Air Quality Management District (BAAQMD) is around 14.2 Mg/day (15.6 tons / day). The contributions from other pollutant factors are not nearly as large; nonetheless, they are still noteworthy. BAAQMD has imposed New Source Review (NSR) requirements and Best Available Control Technology (BACT) levels for new stationary I.C. engines. The purpose of BACT is to achieve the lowest level of engine exhaust emissions using today’s proven control technology. The BACT level for NOx is presently set at 0.00056 mg/J (1.5 g/bhp-hr) or less for stationary I.C. engines. The BACT level for each of the other exhaust pollutants has not been set since they seldom require a BACT determination. In the event BACT is triggered, a case-by-case BACT evaluation will be performed. The placement of BACT and NSR standards on stationay I.C. engines has aided the BAAQMD in achieving better local air quality. More stringent standards may be imposed as long as the need for better air quality exists.
Development of a Ceramic Particulate Trap for Urban Buses
Authors: Cornetti G. M. , Messori P. P. , Operti C.
Published: October 2009

Main aspects concerning the development of a burner-assisted ceramic particulate trap for diesel engines equipping urban buses have been examined. First of all the basic phenomena causing particulate accumulation inside the filter and chemical and physical parameters controlling regeneration have been studied. Then systematic measurements were performed in different running conditions on an urban bus equipped with a ceramic filter using a diesel fuel burner to start regeneration in order to verify the theoretical approach. These tests showed that: (1) The amount of particulate collected by the trap is a function of the different flat and/or hilly circuits inside the city; (2) regeneration has to be started with a proper amount of particulate collected (too little does not allow complete regeneration, too much is dangerous for trap life). Therefore an on-line continuous monitoring system of the particulate collected has been developed. When a certain level is exceeded, the filter is bypassed and regeneration starts. The system is based on the direct measurement of the exhaust flow by means of a Venturi and the pressure loss on the trap. The amount of particulate is defined by real time comparison of Venturi differential pressure and filter pressure loss. Urban buses were purposely designed in order to be equipped with a ceramic particulate trap plus the control unit. Tests of the system have been successfully performed on the buses operated on flat and hilly circuits inside the city.
On the Computation of Emissions From Exhaust Gas Composition Measurements
Authors: Myers J. , Myers M. , Myers P.
Published: October 2009

This paper presents a calculation technique and related computer program to yield mass emission rates from measured exhaust gas composition and fuel flow rate or fuel plus air flow rate (if air flow rate is measured). The sensitivity of the computed emission rates to (1) the method of calculation and (2) experimental measurement errors is investigated. It is recommended that published emission rates be the average of the rates computed by several different methods, as discussed in this paper, to minimize the effect of experimental variations in measurement. This, plus use of the computer program presented, would standardize the assumptions used in computing emissions and minimize differences in reported emission rates from different laboratories.
Emissions From IC Engines Fueled With Alcohol–Gasoline Blends: A Literature Review
Authors: Bata Reda M. , Elrod Alvon C. , Rice Richard W.
Published: October 2009

Since air pollution by automotive exhaust gases is of increasing concern around the world, an examination of the work that has been done with regard to evaluating and reducing it can help focus future efforts in dealing with it. Alcohol-containing fuels not only have been shown to have the potential to produce less of many of the polluting gases, but they also constitute a viable alternative to gasoline from the standpoint of efficiency and reducing dependence on the rapidly dwindling supply of petroleum fuel. This report provides a survey of the literature concerning research reported since 1975 on emissions from IC engines operating on alcohol-gasoline fuel blends. The effects of alcohol on the exhaust emissions (carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and the aldehydes (CHO)) are reviewed. A comparison is made of the emissions benefits achieved when methanol or ethanol is used either in neat form or as the blending agent with gasoline. The primary dependent variable considered is emission level (reported on various bases) with the main independent variables being fuel composition, equivalence ratio, and ignition timing. Brief mention is also made of the potential emissions reduction that may be achieved by using dissociated methanol.
Combustion Phenomena of Alcohols in C. I. Engines
Authors: Saeed M. N. , Henein N. A.
Published: October 2009

A study was conducted on a direct-injection, single-cylinder, research-type diesel engine to determine the effect of adding ethanol or isopropanol to diesel fuel on the ignition delay period. The test parameters were alcohol content, intake-air properties, and fuel-air ratio. It was found that the ignition delay of alcohol-diesel blends is prolonged as the alcohol content is increased. Ethanol-diesel blends developed longer ignition delays than those developed by isopropanol-diesel blends. The results showed that ignition delay of alcohol-diesel blends can be effectively shortened using intake-air preheating and/or supercharging. The high activation energy of alcohols with respect to diesel fuel is believed to be responsible for the long ignition delays associated with the use of alcohols as alternate fuels in compression ignition engines.
Extraction Techniques and Analysis of Turbulence Quantities From In-Cylinder Velocity Data
Authors: Catania A. E. , Mittica A.
Published: October 2009

In addition to the frequently used statistical ensemble-average, non-Reynolds filtering operators have long been proposed for nonstationary turbulent quantities. Several techniques for the reduction of velocity data acquired in the cylinder of internal combustion reciprocating engines have been developed by various researchers in order to separate the “mean flow” from the “fluctuating motion,” cycle by cycle, and to analyze small-scale engine turbulence by statistical methods. Therefore a thorough examination of these techniques and a detailed comparison between them would seem to be a preliminary step in attempting a general study of unconventional averaging procedures for reciprocating engine flow application. To that end, in the present work, five different cycle-resolved data reduction methods and the conventional ensemble-average were applied to the same in-cylinder velocity data, so as to review and compare them. One of the methods was developed by the authors. The data were acquired in the cylinder of a direct-injection automotive diesel engine, during induction and compression strokes, using an advanced hot-wire anemometry technique. Correlation and spectral analysis of the engine turbulence, as determined from the data with the different procedures, were also performed.
Material Property Evaluation of Thick Thermal Barrier Coating Systems
Authors: Brink R. C.
Published: October 2009

Coating system optimization is a critical step in the design and development of plasma-sprayed thermal barrier coatings (TBC’s) for diesel engines. Physical and mechanical property measurements and bench screening tests were performed to evaluate the candidate TBC systems. Additional understanding of the material behavior and failure mechanisms of thick TBC’s gained from the property measurements and bench testing was identified. A specific graded zirconia (ZrO2)/bond (NiCrAlY) coating material system with good strain tolerance and fatigue resistance was selected for follow-on diesel engine durability testing.
Reliability Evaluation of Shrouded Blading Using the SAFE Interference Diagram
Authors: Singh M. P. , Vargo J. J.
Published: October 2009

The SAFE Interference Diagram is shown to be useful in the design reliability evaluation of shrouded blading, including long-arc shrouding construction. This method provides an alternate method to the widely used Campbell diagram and also brings in more information for easier design evaluation. The SAFE diagram uses the natural frequencies of an entire bladed disk rather than individual blade or packet frequencies. In addition, it compares frequencies, mode shapes, and speed to evaluate whether a resonance occurs. Theoretical arguments are provided for the validity of the SAFE Diagram and its usefulness is shown by practical examples. This method provides an easier means to show why long-arc shrouding works and also when it might not.
A Ruggedized Design Approach to Reduce Maintenance and Enhance the Efficiency of High and Intermediate Pressure Steam Turbines
Authors: Conway L. , Martin H. F. , Stock A. L. , Vaccaro F. R.
Published: October 2009

The industry issues of minimizing maintenance and maintaining turbine performance with operating time have been systematically addressed using creative approaches to control wear, erosion, vibration, and distortion of critical High-Pressure (HP) and Intermediate-Pressure (IP) Steam Turbine components. The important components were identified utilizing a new technique to analyze turbine high maintenance areas. New technology advances were utilized to understand the causes of the maintenance, and to reduce or eliminate it. The technology advances discussed in the paper are in the area of three-dimensional computer programs, materials, coatings, modern computer-aided drafting, and verification testing. These, in conjunction with new creative design approaches for the critical components, have resulted in a ruggedized HP and HP/IP turbine design, which is retrofittable in today’s operating units. Of special interest are the steps taken to give rapid and individually customized attention from design through manufacturing to each unique situation and utility. Among the benefits achieved are up to a 50 percent overall reduction in maintenance, up to 120 Btu/kWh (30 kcal/kWh) reduction in heat rate, and an increased cyclic duty capability for the ruggedized turbines.
Development of a Thermal Analysis Model for a Nuclear Spent Fuel Storage Cask and Experimental Verification With Prototype Testing
Authors: Hwang J. Y. , Efferding L. E.
Published: October 2009

A thermal analysis evaluation is presented of a nuclear spent fuel dry storage cask designed by the Westinghouse Nuclear Components Division. The cask is designed to provide passive cooling of 24 Pressurized Water Reactor (PWR) spent fuel assemblies for a storage period of at least 20 years at a nuclear utility site (Independent Spent Fuel Storage Installation). A comparison is presented between analytical predictions and experimental results for a demonstration cask built by Westinghouse and tested under a joint program with the Department of Energy and Virginia Power Company. Demonstration testing with nuclear spent fuel assemblies was performed on a cask configuration designed to store 24 intact spent fuel assemblies or canisters containing fuel consolidated from 48 assemblies.
Rub Interactions of Flexible Casing Rotor Systems
Authors: Choy F. K. , Padovan J. , Batur C.
Published: October 2009

Rub interactions between a rotor assembly and its corresponding casing structure has long been one of the major causes for machine failure. Fracture/fatigue failures of turbine impeller blade components may even lead to catastrophic consequences. This paper presents a comprehensive analysis of a complex rotor-bearing-blade-casing system during component rub interactions. The modal method is used in this study. Orthonormal coupled rotor-casing modes are used to obtain accurate relative motion between rotor and casing. External base vibration input and the sudden increase of imbalance are used to simulate suddenly imposed adversed operating condition. Nonlinear turbine/impeller blade effects are included with the various stages of single/multiple blade participation. A variable integration time step procedure is introduced to insure both accuracy and efficiency in numerical solutions. The dynamic characteristics of the system are examined in both the time domain and the frequency domain using a numerical FFT procedure. Nonlinear bearing and seal forces are also included to enhance a better simulation of the operating system. Frequency components of the system spectral characteristics will be correlated with the localized rub excitations to enable rub signature analysis. A multibearing flexible casing rotor system will be used as an example. Conclusions will be drawn from the results of an extensive parametric study.
Spray Automated Balancing of Rotors: Concept and Initial Feasibility Study
Authors: Smalley A. J. , Baldwin R. M. , Schick W. R.
Published: October 2009

This paper describes a new balancing concept: Spray Automated Balancing Of Rotors (SABOR). The Fuel Air Repetitive Explosion (FARE) process of metal film deposition is used to apply discrete amounts of metallic or ceramic particles to a spinning rotor at a controlled angular location on the rotor. In this way, without stopping the rotor, its mass eccentricity is changed in a manner designed to reduce the vibration sensed by a balancing machine. The system design and control for implementing SABOR are described. Preliminary results are presented from a demonstration rig that confirm the ability of the method to control both angle of application and rate of application to the extent necessary for effective automated balancing. The method is used to balance a spinning disk without stopping it. Results are presented which show that the bond strengths of materials deposited by the FARE process for use in small gas turbine engines are acceptable for the level of centrifugal stresses expected. Fatigue tests of sprayed samples show the data to be indistinguishable from those available for specimens hand-ground according to current balancing practice.
Laboratory Study of a Steam Turbine Rotor Weld Repair
Authors: Fuentes K. , Oberle K.
Published: October 2009

In 1986, a large utility discovered a crack in its IP/LP steam turbine rotor and weld repair was chosen as the most cost-effective alternative. The repair consisted of severing the rotor between the 12th and 13th stages and welding a new forging, replacing the 9th and 12th stages, to the remaining original rotor. A test rotor was prepared from the scrapped rotor section using procedures similar to the actual rotor repair. The test rotor was subjected to a mechanical and metallurgical test program to determine the properties of the material in the weld-repaired area. Testing included: nondestructive examination of the rotor bore, chemical analysis of the rotor material, metallographic examination, hardness, tensile, rotating beam fatigue, fracture appearance transition temperature, J-integral fracture toughness, and stress rupture testing. In addition, boresonic inspection records were compared to the destructive examination of the scrapped section of the rotor and four disk sections from the original rotor were tested for evidence of a temper embrittlement gradient.
Physical and Chemical Characteristics of Cenospheres From the Combustion of Heavy Fuel Oil
Authors: Clayton R. M. , Back L. H.
Published: October 2009

Characterization of an existing sample of cenospheres produced during residual-oil-fired steam power plant combustion included: scanning electron microscopy of surface structure; photomicrography of particle cross sections; measurement of porosity, surface area, and density; and measurement of chemical composition. The studies showed that typical large (100–200 μm) and small (20–40 μm) cenospheres were spheroidal and hollow and had at least one blowhole. The sizes of the blowholes range from 10 to 50 percent of the diameters of the cenospheres. The ratio of outer to inner diameter of the shell was of the order of 1.3–1.4. The shells are porous, the larger ones appearing spongelike, the smaller ones appearing smoother but containing many pores a few micrometers in diameter. The solid portions of the shell appear flaky and layered. A typical cenosphere contained only about 18 percent solid material on a volumetric basis. A relatively concentrated percentage content of elements S, Fe, Na, and V was indicative of the potential contribution to high-temperature corrosion from cenosphere deposition on heat exchanger surfaces.