bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Development of a Landfill Gas Combustion System for the Typhoon Gas Turbine
Authors: Ecob David J. , Boyns Michael B. , Walsh Steve , McClave Ken , Hunt A. Allen
Published: February 2015

This paper presents design, initial combustion development testing and engine validation results of a combustion system which is capable of burning a medium CV landfill gas or conventional diesel oil in a 5MW gas turbine.

Initial rig testing of the original combustion system burning a simulated medium CV gas revealed stability problems and inherently poor combustion efficiencies.

A study of primary zone flow patterns and fuel placement led to the conclusion that the problems were due to axial injection of the gas. Subsequently a modified dual fuel injector was designed which relied on swirled instead of axial injection. The modified injector design also embodies a passive purge feature, which uses combustor wall pressure drop to feed air directly into the gas swirler passages. This prevents ingestion of harmful combustion products when running on diesel oil.

Extensive rig testing demonstrated encouraging combustion efficiencies and emissions using 40% and 54% methane landfill gas compositions across a simulated engine load profile. Operation of the modified injector on diesel oil however, demonstrated a need for the incorporation of an anti-carbon feature. The effectiveness of this anti-carbon modification was verified as part of a ‘validation engine cycle’ simulating the actual engine operating procedure from light up to shutdown. Post test inspection revealed carbon deposition to be significantly reduced. Combustion efficiencies, emissions, traverse quality, metal temperatures, stability and noise were all found to be satisfactory.
Application of Rainbow Thermometry to the Study of Fuel Droplet Heat-Up and Evaporation Characteristics
Authors: Sankar Subramanian V. , Buermann Dale H. , Bachalo William D.
Published: February 2015

Advanced, non-intrusive, laser-based diagnostics are being developed for simultaneously measuring the size, velocity, temperature, and instantaneous regression rates of vaporizing/burning fuel droplets in polydisperse flow environments. The size and velocity of the droplets are measured using a conventional phase Doppler particle analyzer (PDPA), whereas the droplet temperatures are simultaneously measured with a rainbow thermometer. This integrated diagnostic has been applied to the study of fuel droplet heat-up characteristics in a swirl-stabilized kerosene spray flame. It has also been shown that a novel extension of rainbow thermometry can be used to additionally extract the instantaneous droplet vaporization rate. The feasibility of measuring the instantaneous regression rate has also been demonstrated using controlled experiments with a vaporizing/burning stream of ethanol droplets.
Numerical Investigation of the Clocking Effects in a Multistage Turbine
Authors: Eulitz Frank , Engel Karl , Gebing Hermann
Published: February 2015

The paper presents a numerical study on turbine clocking using a stator/rotor/stator model configuration of equal pitches. The results of time accurate flow calculations for four clocking positions are compared. The unsteady, two dimensional Reynolds averaged equations are solved using a one-equation turbulence model by Spalart and Allmaras. In absence of a transition model, the flow is assumed to be fully turbulent.

In a first analysis of the unsteady data, emphasis has been put on the loss production of the clocked stator. A Fourier decomposition of the specific entropy at the stator entry and exit is discussed. It is shown that clocking determines the degree of interaction of a stator with the wake of another upstream stator for a given rotor speed. Further, clocking has little upstream influence.
Measurements of Time-Varying Jet Isopleths Using Dual Light Sheet PLIF
Authors: Campbell Robert P. , Checkel M. David , Wilson David J.
Published: February 2015

Mass transfer analogies have long been used to experimentally determine the distribution of cooling fluid through pointwise sampling for turbine blade, nozzle or combustor film cooling. The behavior of a turbulent jet or plume flowing into its surroundings cannot be fully understood from point measurements alone, however. Full-field measurement of the instantaneous distribution of cooling fluid can reveal the structure and mechanisms governing cooling performance. This paper describes an improved dual light sheet PLIF (Planar Laser Induced Fluorescence) technique developed for full field concentration measurements. An analytical model of laser light sheet / fluorescent dye interaction was formulated and used to evaluate the light sheet attenuation corrections. With the more common single light sheet technique, these corrections lead to substantial concentration uncertainty which can be substantially reduced by using a dual light sheet. The dual light sheet technique was used to study the time-varying position and area of concentration isopleths for a round jet issuing into quiescent surroundings. Results show that, although concentrations at any point vary widely with time, the area within a given concentration isopleth remains virtually constant.
Integrated Predictive Diagnostics: An Expanded View
Authors: Hansen Robert J. , Hall David L. , Nickerson G. William , Phoha Shashi
Published: February 2015

In a previous paper (Hansen et al., 1995), a conceptual framework for developing a true prognostic or predictive diagnostic capability was described. The current paper expands on this framework by describing micro-mechanical and dynamic models, sensors and data fusion, signal processing, approximate reasoning, distributed architecture, and human factors research and development being conducted to provide such a capability for a broad range of applications. These include both autonomous and man-in-the-loop decision making about maintenance actions and local and geographically distributed monitoring and data analysis architectures.
Study of Radial Tip Clearance Effects in a Low-Speed Axial Compressor Rotor
Authors: Nikolaou I. G. , Giannakoglou K. C. , Papailiou K. D.
Published: February 2015

A three-dimensional space marching code is used for the numerical modelling of the flow in an isolated axial flow compressor rotor. The rotor is analyzed at four operating points, up to near stall conditions. Numerical results are first validated versus available experimental data and then further exploited in order to illuminate flow patterns in the inter-blade region. The tip leakage impact on the main passage flow and losses level as well as the effect of blade loading on the hub corner stall extent and the radial displacement of the flow are fully detailed. In order to account for the rotor geometry, the modifications performed in an existing software are mainly concerned with the accurate modelling of the clearance which is formed above the curved blade tip; for this purpose, a local H-type mesh is embedded to the main passage grid.
Quasi-Three-Dimensional Simplified Method for a Transonic Compressor Rotor
Authors: Tsamourtzis V. , Bölcs A.
Published: February 2015

A quasi three-dimensional method has been developed to calculate the transonic flow in a compressor rotor. The method allows changes in the stream tube thickness and mean radius evolution through the rotor. This blade-to-blade method uses original concepts in order to be rapid (≈ 3–4 sec CPU on a HP 715 workstation), to find the precise location of the shocks (and thus the flow values on them) and the flow distribution around the profile, and finally to cover a large field of “Off-Design” operating points. Thus, it can be used in the process of optimization of a transonic compressor. The supersonic flow at the inlet as well as the oblique shock configuration inside the cascade are calculated by methods based on the characteristics theory. Conditions with attached shock wave (and thus unique incidence angle) or with detached shock wave can be calculated. Quasi-3D equations were developed (Bölcs and Tsamourtzis, 1991). The subsonic flow is calculated by a streamline curvature method, with some new concepts, and finally the shock in the inter-blade canal is found by a combination of the supersonic and subsonic flow values. This method was combined, in a S1 - S2 calculation, with a throughflow method (Sayari and Bölcs, 1995) in order to be validated by comparing the results with the measurements provided by NASA - Lewis Research Center, on a transonic compressor rotor (Strazisar T.; 1994).
Numerical and Experimental Investigation of a Rich Quench Lean Combustor Sector
Authors: Koopman Johannes W. , Griebel Peter , Hassa Christoph
Published: February 2015

The flow in a three sector model, representing a segment of an annular rich quench lean combustor for an aeroengine is investigated. Detailed knowledge of flow, temperature and species concentration distributions is of decisive importance to control the NOx formation, essential to the RQL concept. Velocities, temperatures and species concentrations are measured. They are partly used to aquire data on the inlet boundaries in the numerical calculation and partly used to compare with the numerical results. The calculation reveals many details which are not accesable in the experiment. It also shows the effects of the specific inlet dataset. Experimental data and numerical results furnish complementary information.
NOx Control in Black Liquor Fuel Gas Combined Cycles
Authors: Sliger Rebecca N. , Berz Marcel D. , Kramlich John C. , Malte Philip C.
Published: February 2015

The gasification of black liquor, followed by its use in gas turbine engines, is an emerging alternative to the direct firing of the liquor in Tomlinson recovery boilers. Many gasification systems, however, convert the fuel nitrogen present in the liquor into ammonia (NH3) in the fuel gas, which leads to unacceptable NOx emissions in gas turbine combustors.

This work uses detailed chemical kinetic modeling to examine the influence of two combustor modifications for the control of NOx emissions from black liquor fuel gas combustion. Availability analysis is also used to evaluate the influence of these NOx control choices on the thermodynamic architecture of the overall system. A rich-quench-lean configuration makes use of air staging. An alternative is to use a hot, rich external precombustor to remove NH3 before the main combustor. Here, the external, rich stage operates at around 30% theoretical air. Adiabatic temperatures are too low to obtain good NH3 reduction, so recuperative heating is necessary.
Time-Frequency Analysis of Compressor Rotating Stall by Means of Wavelet Transform
Authors: Liao Shengfang , Chen Jingyi
Published: February 2015

In this paper, an application of Wavelet Transform, which is a newly developed time-frequency technique of signal processing, is demonstrated in analyzing compressor rotating stall signals. In contrast to conventional signal processing methods, e.g. Fourier Transform, Wavelet Transform is very suitable for analyzing transient processes as rotating stall inception in compressors. In this study, some typical rotating stall signals are processed via Morlet’s wavelet. It is concluded that Wavelet Transform has a great advantage in detecting rotating stall inceptions, which are usually very weak and embedded in relatively stronger noises. In the diagrams resulted from the transform, every emergence of precursor as well as full stall signals of a certain frequency is illustrated versus time.
A Study of the Behaviour of Flow in a Diagonal-Flow Turbomachine
Authors: Ray Arjun Sarathi
Published: February 2015

Experiments were conducted on a diagonal-flow machine to study the behaviour of flow. Measurements showed that at reduced flow rates, reversal of flow occurs near the tip upstream of the rotor and near the hub downstream. At high flow rates, the flow reverses near tip at downstream only. In fact, there is only a limited regime of operation where the flow is not reversed before or after the impeller. The best fluid-dynamic efficiency was observed to be midway of this non-reversed flow regime.

Through-flow solutions of the mean hub-to-tip streamsurface were carried out by streamline curvature computation and compared with experimental results. The comparison showed good agreement of the predicted values with the experimental data. However, attempts to compare theoretical estimates of rotor losses with experimental measurements showed that the existing loss models are inadequate for loss prediction and further work is required in this direction.

The head-flow characteristic of the machine showed a droop at reduced flow rates, typical of what one usually notices in an axial-flow machine with the onset of blade stall. Study of the time history of velocity downstream of rotor illustrated that unlike rotating ‘stall-cells’ in axial-flow machines, the blade stall in the present case did not possess any regular pattern nor any unique speed of propagation. Near the hub at downstream of rotor, where the flow finally reverses upon reduction of flow rate, the stall appeared as patches of ‘blockage’ type disturbance over an otherwise systematic train of blade wakes when the flow coefficient reaches a value where the droop in the characteristic curve starts.
An Implicit Algorithm for Stator-Rotor Interaction Analysis
Authors: Michelassi V. , Adami P. , Martelli F.
Published: February 2015

A simple time-accurate algorithm is presented for the computation of the unsteady stator-rotor interaction. The algorithm is based on the scalar approximate factorization method originally developed for the computation of complex three-dimensional steady flows. The method introduces a physical time step, used to march in time, and a numerical time step to iterate in between physical time steps. The method is formulated so as to take full advantage of the implicit formulation and provide an implicit treatment of the unsteady terms. A set of preliminary tests on a turbine stage, still in the experimental testing phase, proved the speed and accuracy of the method which was able to capture the essential features of a transonic stage.
Modelling of the Tip Clearance Losses in Axial Flow Machines
Authors: Nikolos I. K. , Douvikas D. I. , Papailiou K. D.
Published: February 2015

The possibility of predicting the total pressure loss radial distribution, due to the tip clearance presence, is examined in this paper. Models advanced for the diffusion of a line vortex are used for the simulation of the leakage vortex induced velocity and pressure fields, with sufficient success. The leakage vortex strength seems to control directly only a small part of the total pressure loss distribution, the one connected with the pressure deficit and the rotating flow. The remaining profiles result as functions of a free parameter — the constant of integration — and an assumption is needed to close the problem. The widely proposed observation for lost secondary jet kinetic energy is considered as a method of predicting the total amount of tip clearance loss in successive planes inside and downstream the blade passage.

A calculation procedure for predicting the tip clearance effects in the flow field inside and downstream the tip clearance, has been developed. The method, being compatible with a meridional flow calculation procedure, accounts for the calculation of the peripherally mean deficit profiles of the various flow quantities. The predictive capability of the calculation procedure is established in a wide range of test cases, including axial flow compressor cascades, isolated rotors and multi-row machines. The radial variation of tip clearance pressure loss is calculated with sufficient accuracy for engineering purposes.
An Analysis of the Aeroelastic Behaviour of a Typical Fan-Blade With Emphasis on the Flutter Mechanism
Authors: Marshall J. G. , Imregun M.
Published: February 2015

Aeroelasticity phenomena are characterised by the interaction of fluid and structural domains, whose describing equations are nonlinear. Classical prediction methods are generally based on treating the two domains separately while integrated (or coupled) approaches link them via boundary conditions throughout the solution phase. In turbomachinery environments, the aeroelasticity problem is further compounded by the fact that blades vibrate with a relative phase with respect to each other, the value of which is not necessarily known. Using a 3D thin-layer Reynolds-averaged Navier-Stokes solver and a 3D structural model, various coupled and uncoupled flutter analysis methods are compared with particular emphasis on inter-blade phase angle. A typical fan geometry, the NASA Rotor 67 blade, was chosen as the test case since steady-flow measurements are available for this particular structure. Two flow conditions, near peak-efficiency and near stall, were investigated for inter-blade phase angles of −90°, 0°, 90° & 180°. The performance of the uncoupled analysis with shape correction was first compared with that of the uncoupled multi-passage analysis. A coupled multi-passage analysis was performed next in order to highlight the importance of fluid/structure interaction. It was found that significant natural frequency shifts could exist between the structural and aeroelastic modes of the system, which suggests that coupled analyses may be more appropriate for such cases.
Experimental Investigation of a Single Stage Axial Flow Compressor With Controlled Diffusion Airfoils
Authors: Pieper S. , Schulte J. , Hoynacki A. , Gallus H. E.
Published: February 2015

In order to verify an inverse design concept for modern compressor bladings, a subsonic compressor front stage with IGV was investigated.

One objective of the design was to survey the flow field in detail, with emphasis on 3D viscous and unsteady aspects of the flow. Therefore, the compressor was equipped with various steady and unsteady measurement techniques. Additionally, a compressor design was chosen that allows an extension up to three stages with regard to the investigation of multistage axial compressor flow behavior.

Test results of the steady measurements are discussed for IGV, rotor, and stator flow at design conditions as well as the overall stage performance. The measurements of the steady flow behavior confirm the expected design performance and show the high potential of the controlled diffusion airfoil concept. Only at the side walls near hub and casing there are some differences between design and measurement due to the complex three dimensional flow.

For the study of unsteady effects, detailed measurements using hot-wire probes, glue-on hot-films, and semiconductor pressure transducers were performed. All measurements are evaluated using the ensemble-average technique. The results show how the boundary layers of the inlet guide vanes and stator blades develop in a flow that is periodically disturbed by the rotor. Time-dependent pressure distributions at midspan of both stators are described. In addition, the unsteady pressure field at the casing above the rotor was investigated. The minimum wall pressure is located away from the blade suction surface. The effects of tip clearance flow on the performance are presented. The radial extent covers 15% span from the tip. At rotor exit, the unsteady pressure field and the time-dependent three-dimensional velocity vectors illustrate the salient features of the viscous flow associated with the rotor.
The Blast Basket: A New Component Used in Testing Large, High Bypass Ratio, Fan Engines
Authors: Adkins Richard C. , Anas Arsil
Published: February 2015

The need for using blast baskets when testing large engines with a high bypass ratio is explained. A theory has been developed to enable the pressure drop characteristics of blast baskets to be determined and this has been validated by experimental data. The theoretical approach has then been used in order to construct a design chart for use by constructors of engine test facilities, engine manufacturers and engine users who have a need to modify their existing test facilities.
A Nonintrusive Rotor Blade Vibration Monitoring System
Authors: Jones Henry
Published: February 2015

A technique for measuring turbine engine rotor blade vibrations has been developed as an alternative to conventional strain-gage measurement systems. Light probes are mounted on the periphery of the engine rotor casing to sense the precise blade passing times of each blade in the row. The timing data are processed on-line to identify (1) individual blade vibration amplitudes and frequencies, (2) interblade phases, (3) system modal definitions, and (4) blade static deflection. This technique has been effectively applied to both turbine engine rotors and plant rotating machinery.
Development of Gas Turbine for Air-Blown Gasification
Authors: Wada K. , Sasada T. , Hayashi H.
Published: February 2015

The development progress and operation results with the gas turbine developed for the first coal gasification pilot plant (200T/D) in Japan are reported hereafter.

The gas turbine based on the scale down of the commercial machine (H25), is called H14. To deal with coal gasification, the development of the combustor is main subject because of the low caloric value of fuel. We developed the combustor through many combustion tests with simulation gas, and the selected combustor was supplied to the actual gas test at the pilot plant. We could grasp the limit of stable combustion of the combustor because the fuel characteristics of actual fluctuated sharply. In addition, we could experience phenomena peculiar to the gasification such as the back fire problem and finally succeeded in air extraction linkage operation by no means inferior to the used coal fired thermal power generation. Thus we established the gas turbine technology for coal gasification and opened a way to future large gasification plants.
Adaptability of the Solar Advanced Turbine Systems to Biomass and Coal Derived Fuels
Authors: White David J. , LeCren Richard T. , Wen Chaur S.
Published: February 2015

SolarTurbines Incorporated (Solar) is developing the technologies that are to be used for a highly efficient, recuperated, Advanced Turbine System (ATS) that is aimed at the dispersed power generation market. With ultra-low-emissions in mind the primary fuel selected for this gas turbine engine system is natural gas. Although this gas fired ATS (GFATS) will primarily employ natural gas, the use of other fuels, particularly those derived from coal and renewable resources cannot be overlooked. The enabting technologies necessary to direct-fire coal in gas turbines were developed during the 1980s. This Solar development, co-sponsored by the U.S. Department of Energy (DOE), resulted in the testing of a full size coal-water-slurry fired combustion system. In parallel with this program the DOE funded the development of integrated gasification combined-cycle systems (IGCC). This report describes the limitations of the Solar ATS (recuperated engine) and how these limitations lead to a recommended series of modifications that will allow the use of these alternative fuels.

Three approaches have been considered: direct-fired combustion using either a slagging combustor, or a pressurized fluidized bed (PFBC), externally or indirectly fired approaches using pulverized fuel, and external gasification of the fuel with subsequent direct combustion of the secondary fuel. Each of these approaches requires substantial hardware and system modifications for efficient fuel utilization. The integration issues are discussed in the sections below and a recommended approach for gasification is presented.
Study of Hot Streak Phenomena in Subsonic and Transonic Flows
Authors: Dorney Daniel J. , Sondak Douglas L.
Published: February 2015

Experimental data have shown that combustor hot streaks can lead to pressure side “hot spots” on first-stage turbine rotor blades. Although many modern turbines operate at high subsonic or transonic flow speeds, the majority of bot streak experiments and numerical simulations performed during the last decade have been for low-speed flows. The presence of shock waves in a turbine stage can significantly affect the surface temperature distributions, and a knowledge of the interaction between shock waves and combustor hot streaks may help in the turbine design process. In the present investigation, quasi-three-dimensional unsteady Navier-Stokes simulations have been performed for a high-pressure turbine operating at two vane settings. At the open-vane setting, the flow is predominantly high subsonic with no trailing-edge shock waves, and at the closed-vane setting there are trailing-edge shocks.
Intelligent Pressure Measurement for Turbo Machinery Applications
Authors: Greener Derek
Published: February 2015

Multiple pressure data acquisition has typically consisted of hundreds of pipes connected via a test-bed interface to mechanical multiplexers and/or to groups of electronically scanned sensors. This paper describes a new method of high speed digital pressure scanning with intelligent pressure modules and its consequent impact on turbine testing methods and working practices. Also discussed is the remote calibration of modules and the concept of pre-rig or build shop connecting pressure tappings direct to the test measuring equipment, thus reducing commissioning, calibration and down time on the test-bed.
Processing of Circumferential Temperature Distributions for the Detection of Gas Turbine Burner Malfunctions
Authors: Tsalavoutas A. , Mathioudakis K. , Smith M. K.
Published: February 2015

A method for analysing the circumferential temperature pattern measured at the turbine exit of Gas Turbines is presented. The purpose of the analysis is to connect the form of the temperature pattern to the condition of the hot section, and more particularly, to burner malfunctions. The behaviour of temperature patterns for different conditions of operation is discussed, on the basis of available experimental data. It is shown that with appropriate formulation, even small variation of the temperature pattern can be detected, and the particular malfunctioning burners can be identified. The proposed method exhibits a very high sensitivity to even small changes in burner operating condition, giving thus the possibility for improving corresponding techniques currently in use.
Friction Damping of Hollow Airfoils: Part I — Theoretical Development
Authors: Griffin J. H. , Wu W.-T. , El-Aini Y.
Published: February 2015

The quest for higher performance engines in conjunction with the requirement for lower life cycle costs has resulted in stage configurations that are more susceptible to high cycle fatigue. One solution is the use of innovative approaches that introduce additional mechanical damping. The present paper describes an approach that may be used to assess the benefits of friction dampers located within internal cavities of a hollow structure.

The friction dampers used in this application are often relatively thin devices that, if unconstrained, have natural frequencies in the same range as the natural frequencies of the hollow airfoil. Consequently, the analytical approach that is developed is distinct in that it has to take into account the dynamic response of the damper and how it changes as the amplitude of the vibration increases. In this paper, results from the analytical model are compared with independently generated results from a time integration solution of a three mass test problem. Results from the analytical model are compared with experimental data in a companion paper.
Friction Damping of Hollow Airfoils: Part II — Experimental Verification
Authors: El-Aini Yehia M. , Benedict Barry K. , Wu Wen-Te
Published: February 2015

The use of hollow airfoils in turbomachinery applications, in particular fans and turbines, is an essential element in reducing the overall engine weight. However, state–of–the–art airfoil geometries are of low aspect ratio and exhibit unique characteristics associated with plate–like modes. These modes are characterized by a chordwise form of bending and high modal density within the engine operating speed range. These features combined with the mistuning effects resulting from manufacturing tolerances make accurate frequency and forced response predictions difficult and increase the potential for High Cycle Fatigue (HCF) durability problems. The present paper summarizes the results of an experimental test program on internal damping of hollow blade–like specimens. Friction damping is provided via sheet metal devices configured to fit within a hollow cavity with various levels of preload. The results of the investigation indicate that such devices can provide significant levels of damping provided the damper location and preload is optimized for the modes of concern. The transition of this concept to actual engine hardware would require further optimization with regard to wear effects and loss of preload particularly in applications where the preload is independent of rotational speed. Excellent agreement was achieved between the experimental results and the analytical predictions using a micro–slip friction damping model.
Modeling Sulfur Dioxide Capture in a Pulverized Coal Combustor
Authors: Nair Rajesh B. , Yavuzkurt Savas
Published: February 2015

The formation and capture of sulfur dioxide in a pulverized coal combustor is investigated. A two-dimensional, steady, axisymmetric code, PCGC-2 (Pulverized Coal Gasification and Combustion - 2 Dimensional) originally developed at Brigham Young University has been used to simulate combustion of the pulverized coal. This paper represents part of a project to investigate simultaneously enhancing sulfur capture and particulate agglomeration in combustor effluents. Results from the code have been compared to experimental data obtained from MTCI’s (Manufacturing Technology and Conversion International) test pulse combustor which generates sound pressure levels of ∼180 dB. The overall goal behind the pulse combustor program at MTCI is to develop combustors for stationary gas turbines which use relatively inexpensive coal-based fuels. This study attempts to model the capture of sulfur dioxide when injected into a pulse combustor firing micronized coal. While this work does not presume to model the complex gas flow-field generated by the pulsating flow, the effects of the acoustic field are expressed by increased heat and mass transfer to the particles (coal/sorbent) in question. A comprehensive calcination-sintering-sulfation model for single particles was used to model the capture of sulfur dioxide by limestone sorbent. Processes controlling sulfation are external heat and mass transfer, pore diffusion, diffusion through the product layer of CaSO4, sintering and calcination. The model was incorporated into the PCGC-2 program. Comparisons of exit concentrations of SO2 showed a fairly good agreement (within ∼10%) with the experimental results from MTCI.
A Numerical Investigation of Premixed Combustion in Wave Rotors
Authors: Nalim M. Razi , Paxson Daniel E.
Published: February 2015

Wave rotor cycles which utilize premixed combustion processes within the passages are examined numerically using a one-dimensional CFD-based simulation. Internal-combustion wave rotors are envisioned for use as pressure-gain combustors in gas turbine engines. The simulation methodology is described, including a presentation of the assumed governing equations for the flow and reaction in the channels, the numerical integration method used, and the modeling of external components such as recirculation ducts. A number of cycle simulations are then presented which illustrate both turbulent-deflagration and detonation modes of combustion. Estimates of performance and rotor wall temperatures for the various cycles are made, and the advantages and disadvantages of each are discussed.
Development of a Low-Emission Combustor for a 100-kW Automotive Ceramic Gas Turbine (III)
Authors: Sasaki Masafumi , Kumakura Hirotaka , Suzuki Daishi , Ichikawa Hiroyuki , Ohkubo Youichiro , Yoshida Yuusaku
Published: February 2015

A low emission combustor, which uses a prevaporization-premixing lean combustion system for the 100 kW automotive ceramic gas turbine (CGT), has been subjected to performance tests. Now a second combustor prototype (PPL-2), which incorporates improvements intended to overcome a flashback problem observed in an initial combustor prototype (PPL-1), is tested.

The PPL-2 has been designed and built, so that it will substantially expand the stable combustion range. The improvement is accomplished by increasing the air distribution ratio in the lean combustion region to avoid flashback, providing a uniform flow velocity through the throat area and also by diluting the boundary layer so as to suppress flashback. Test results of the PPL-2 combustor show that it expands the flashback limit without affecting the blow out limit and is able to cover the stable combustion range need for the 100kW CGT.
The Effects of Dissolved Oxygen Concentration, Fractional Oxygen Consumption, and Additives on JP-8 Thermal Stability
Authors: Ervin J. S. , Williams T. F. , Heneghan S. P. , Zabarnick S.
Published: February 2015

Since dissolved oxygen participates in fuel deposit formation, knowledge of the effects of dissolved oxygen concentration on fuel thermal stability is critical for fuel system design. In this work, the combined effects of dissolved oxygen availability and additives on jet fuel thermal stability are studied. Experiments with JP-8 jet fuel were conducted in a three-part heat exchanger which simulated a complex thermal and flow environment. The dissolved oxygen content at the flow inlet was varied, and deposition was studied under conditions of either fractional or complete oxygen consumption. The effects of a thermal stability additive package were also studied. An intriguing result found with JP-8 fuels is an increase in deposits formed in heated regions for decreased oxygen consumption, but inverse behavior with the additive package.
Flow Visualization and Leakage Measurements of Stepped Labyrinth Seals: Part 1 — Annular Groove
Authors: Rhode David L. , Johnson James W. , Broussard Daniel H.
Published: February 2015

An improved understanding of a new category of stepped labyrinth seals, which feature a new “annular groove”, was obtained. A water leakage and flow visualization test facility of very large scale (relative to a typical seal) was utilized. Flow visualization experiments using a new method and digital facilities for capturing and editing digital images from an 8 mm video were conducted. The presence of an annular groove machined into the stator land increases the leakage resistance by up to 26 percent for the cases considered here. Tracer particles show the degree of throughflow path penetration into the annular groove (i.e. serpentining), which gives the largest and the smallest leakage resistance improvement over that of the corresponding conventional stepped seal.
Turbine Airfoil Design Optimization
Authors: Goel Sanjay , Cofer John I. , Singh Hardev
Published: February 2015

A new blade design methodology, which allows designers to react rapidly to changes in functional requirements of turbines and transition quickly from concept to design, has been discussed in this paper. This methodology reduces the design cycle time by creating a three-dimensional model of the blade, through concurrent design of multiple two-dimensional blade sections. An efficient direct design procedure has been developed by coupling direct optimization techniques with two-dimensional aerodynamic analysis codes. A method for interpreting the flowfield solution to compute the airfoil quality has been developed and is used to compute the objective function during optimization. Aerodynamic, mechanical and geometry constraints are imposed on the design to ensure that the optimized design meets feasibility requirements of all engineering disciplines. During the design optimization process, the designers’ interactions are simulated through use of rules that are based on designer heuristics. This procedure is used for the design of a high pressure, steam turbine blade; the results are discussed in this paper.
The Role of the Impingement Plate in Array Heat Transfer
Authors: Van Treuren Kenneth W. , Wang Zoulan , Ireland Peter , Jones Terry V. , Kohler S. T.
Published: February 2015

Most research involving arrays of impinging jets was conducted using steady state techniques which allow the impingement plate (through which the gas flows) to achieve an equilibrium (adiabatic) temperature during the test. Invariably, the impingement plate temperature was not reported for these tests as the floating temperature condition was taken to be representative of conditions in the application being modeled. Thermal analysis of gas turbine conditions showed the present authors that conditions in the engine could often be significantly different from this floating plate temperature state. Such conditions include engine operating point transients and situations in which the plate is fixed to the aerofoil in such a way to achieve good thermal contact. Furthermore, the capacity of the impingement plate to contribute to enhanced heat transfer by paying attention to the thermal boundary conditions at its support has not been realized. The influence of the impingement plate temperature on local target surface heat transfer was fully quantified by Van Treuren et al. (1993, 1994 and 1996), using a transient liquid crystal heat transfer technique. Superposition was used to show that the target surface heat flux can be written as the summation af two separate heat transfer coefficients. These temperature difference products quantify the contributions of the impingement plate and the target surface thermal boundary conditions. In other words:(1)q=hjTw-Tj+hpTw-TpVan Treuren et al.’s experiments showed the heat transfer coefficient for target surface heat flux and impingement plate to target surface temperature difference, hp, can be up to 40% of the heat transfer coefficient for plenum to target surface temperature difference, hj, in crossflow areas away from the jet stagnation zone. The present report covers steady state experiments conducted at three average jet Reynolds numbers (10,000, 14,000, and 18,000) and two impingement to target plate spacings (1 and 4) for an inline array of jets. The purpose of the experiments was to determine the adiabatic impingement plate temperature expressed as a non-dimensional temperature difference, θ. The data allow the difference in thermal boundary conditions between the steady state experiments and the transient heat transfer experiments to be accounted for.
An Object-Oriented Approach to Gas Turbine Performance Computation
Authors: Ho Peng Yip , Ng Poh Seng
Published: February 2015

This paper aims to introduce Object-Oriented Programming (OOP) concepts in the context of gas turbine engine performance computations. Objects are collections of data and functions that represents useful elements in an application. They are a means of extending the standard programming language to endow it with data types that are natural metaphors for both physical objects and abstract entities within the application program. Objects are valuable in designing and implementing software because they hide complexity, reducing the amount of knowledge required about any objects in order to use it. These properties also allow objects to be modified or replaced without affecting other areas of the application. Thus, this results in flexible designs and increased productivity by providing reusable software without sacrificing flexibility. The fundamental OOP concepts such as encapsulation, inheritance, and polymorphism are explained and exemplified by source codes from a turbofan engine performance computation software. The advantages of these over traditional programming paradigms are highlighted. The resulting program source code is readable, self-documenting, robust, and highly modular. Furthermore, the software for a turbofan engine is essentially a collection of objects that forms the basic framework for modelling all conceivable forms of gas turbine engines.
Three-Dimensional Blade Boundary Layer and Endwall Flow Development in the Nozzle Passage of a Single Stage Turbine
Authors: Ristic D. , Lakshminarayana B.
Published: February 2015

The three-dimensional viscous flow field development in the nozzle passage of an axial flow turbine stage was measured using a “x” hot-wire probe. The measurements were carried out at one axial station on the endwall and blade surfaces and at several spanwise and pitchwise locations. Static pressure measurements and flow visualization, using a fluorescent oil technique, were also performed to obtain the location of transition and the endwall limiting streamlines. The boundary layers on the blade surface were found to be very thin and laminar, except on the suction surface downstream of 70% axial chord. Strong radial pressure gradient, especially close to the suction surface, induces strong radial flow velocities in the trailing edge regions of the blade. On the endwalls, the boundary layers were turbulent and much thicker, especially near the suction corner of the casing surface, caused by the secondary flow. The secondary flow region near the suction casing surface corner indicated the presence of the passage vortex detached from the blade surface. The boundary layer code accurately predicts the three-dimensional boundary layers on both vane surfaces in regions where the influence of secondary flow is small.
Evaluation of the External Heat Transfer Coefficients in the High-Pressure Turbine of a Full-Scale Core Engine
Authors: Narcus A. R. , Przirembel H. R. , Soechting F. O.
Published: February 2015

The external heat transfer coefficients, necessary for efficient and accurate turbine blade design, have been quantified using three independent methods of data reduction for the high-pressure turbine blades tested in a core engine. Two of the methods utilized external and internal thermocouple data to determine the heat transfer coefficient levels while the third method required the applied heat-flux levels to determine the coefficients. The heat-flux was calculated from the measured potential difference between thermocouple pairs embedded in the external and internal walls of the turbine blades. The instrumented airfoils were calibrated in a laboratory prior to engine testing. The results of the experimental test showed external heat transfer coefficients could be obtained in an engine environment with a ±3.2% minimum absolute uncertainty. All three data reduction methods produced external heat transfer coefficients within a high degree of accuracy and precision for all data locations on the instrumented airfoils. The three data reduction approaches are presented as well as the data for a specific location on a turbine blade for each method of data reduction. In addition, pre-test calibration procedures and data are discussed along with supporting engine instrumentation used to verify the data acquired during the experimental evaluation.
CFD Indications of Premix Flame Stability in a Gas Turbine Combustor
Authors: Allan J.
Published: February 2015

An approach for predicting the relative tendency for weak extinction among similar gas turbine premix combustors is presented. The method involves analyzing CFD (computational fluid dynamics) solutions so as to evaluate the recirculating masses in the primary zone and the resulting potential heating rate of incoming fresh mixture. Results are illustrated for two combustor geometries which look similar but have very different behaviour. The comparison between the combustors agrees with test data when the CFD model incorporates a simulation of the flame. The inadequacy of cold flow models for the purpose is shown.
Integrated Gas Turbine Technology Education at Durham University
Authors: Marsh Harry , Dominy Robert , Gregory-Smith David , He Li
Published: February 2015

Gas turbine technology is a major component in the teaching and research programmes at Durham University. In 1993, the change from the three-year degree course to the four-year Master of Engineering course provided an opportunity to strengthen the teaching of turbomachinery through closer integration of lectures, laboratory work, design, investigative project work and the use of computers for flow prediction. The undergraduate projects link with research in turbomachinery aerodynamics, secondary flows, and unsteady flows. The integrated approach provides graduates with a broad based education and a good understanding of turbomachinery.

Wider aspects include the placement of students for a year of industrial training with a European turbine manufacturer and the organisation of an two-week course for industry on turbine technology. An unusual feature of the Durham approach is the development of turbomachinery based projects to introduce the challenge of engineering into schools and colleges.
Development of a Dual-Fuel Injection System for Lean Premixed Industrial Gas Turbines
Authors: Cowell Luke H. , Rajput Amjad , Rawlins Douglas C.
Published: February 2015

A fuel injection system for industrial gas turbine engines capable of using natural gas and liquid fuel in dry, lean premixed combustion is under development to significantly reduce NOx and CO emissions. The program has resulted in a design capable of operating on DF#2 over the 80 to 100% engine load range meeting the current TA LUFT regulations of 96 ppm (dry, @ 15% O2) NOx and 78 ppm CO. When operating on natural gas the design meets the guaranteed levels of 25 ppm NOx and 50 ppm CO.

The design approach is to apply lean premixed combustion technology to liquid fuel. Both injector designs introduce the majority of the diesel fuel via airblast alomization into a premixing passage where fuel vaporization and air-fuel premixing occur. Secondary fuel injection occurs through a pilot fuel passage which operates in a partially premixed mode. Development is completed through injector modeling, flow visualization, combustion rig testing, and engine testing. The prototype design tested in development engine environments has operated with NOx emissions below 65 ppm and 20 ppm CO at full load. This paper includes a detailed discussion of the injector design and qualification testing completed on this development hardware.
Turbomachinery Teaching and Research as a Supplement to Mechanical Engineering Education
Authors: Engeda Abraham
Published: February 2015

Present and future technological trends are clearly compelling engineers to review efficiencies of energy systems. This is more so currently than ever before with an additional constraint due to stricter emission regulations. For overcoming future energy shortage and tackling any energy concerns, the solution will entirely depend on the engineer’s ability to develop and design high-efficiency turbomachinery, which are by far the largest component of energy producing and conversion systems. The quality of turbomachinery research and teaching is therefore expected to play an important role in developing efficient, reliable, cost worthy, and environment-friendly energy systems for the future.
An Instructional Cogeneration Laboratory Using Gas Turbine Technology
Authors: Banta Andrew , Thinh Ngo Dinh
Published: February 2015

The Mechanical Engineering Department at California State University, Sacramento (CSUS) has completed the design and constructed a $250,000 Instructional Cogeneration Laboratory devoted solely to undergraduate education. This facility will serve about 100 students per year in the Department’s Mechanical Engineering (ME) and Mechanical Engineering Technology (MET) programs. The major components are a 75 kW natural gas fired gas turbine-generator connected to a electrical load bank, a waste heat boiler, four heat exchangers, an absorption chiller and an existing cooling tower. Computer based data acquisition will be used to monitor pressures, temperatures, flows and stack emissions. This project has provided an excellent learning experience for ME and MET students in their senior project classes. Initial laboratory exercises will measure performance of the major pieces of equipment; future plans call for developing a series of heat transfer experiments.