bluuebunny/crossref_metadata_2025 huggingface dataset:
A Quasi-Three-Dimensional Finite Element Solution for Steady Compressible Flow Through Turbomachines
Authors: U¨cer A. S. , Yeg˙en I˙. , Durmaz T.
Published: October 2009

A quasi-three-dimensional solution method is presented for subsonic flows through turbomachines of arbitrary geometry. Principal equations are based on Wu’s formulation of flow on blade-to-blade and hub-to-shroud surfaces, modified such that the same hub-to-shroud principal equation is used for all types of stream surfaces. Blade-to-blade surfaces are assumed to be surfaces of revolution. A stream function is used as the field variable. The problem is solved by finite element method. An iterative solution is used to find the quasi-three-dimensional solution. Solutions at hub, tip, and midheight blade-to-blade surfaces are used to construct a mean hub-to-shroud surface and vice versa, until convergence is obtained. Results indicate that the developed technique is satisfactory for predicting the flow through turbomachine blades.
Eigensolution Reanalysis of Rotor Dynamic Systems by the Generalized Receptance Method
Authors: Palazzolo A. B. , Wang Bo Ping , Pilkey W. D.
Published: October 2009

A method is presented for efficiently calculating the damped natural frequencies of complex rotor bearings systems. The procedure is applicable to the repeated reanalysis of rotor systems during the search for an optimal design. The generalized receptances used in the method are calculated with a series of formulas that improves the convergence characteristics when only an incomplete set of modes is available. A nonsynchronous gyroscopic rotor example is examined to illustrate the reanalysis procedure.
Closed-Form, Steady-State Solution for the Unbalance Response of a Rigid Rotor in Squeeze Film Damper
Authors: Taylor D. L. , Kumar B. R. K.
Published: October 2009

This paper considers the steady-state response due to unbalance of a planar rigid rotor carried in a short squeeze film damper with linear centering spring. The damper fluid forces are determined from the short bearing, cavitated (π film) solution of Reynold’s equation. Assuming a circular centered orbit, a change of coordinates yields equations whose steady-state response are constant eccentricity and phase angle. Focusing on this steady-state solution results in reducing the problem to solutions of two simultaneous algebraic equations. A method for finding the closed-form solution is presented. The system is nondimensionalized, yielding response in terms of an unbalance parameter, a damper parameter, and a speed parameter. Several families of eccentricity-speed curves are presented. Additionally, transmissibility and power consumption solutions are present.
Unsteady Aerodynamics and Gapwise Periodicity of Oscillating Cascaded Airfoils
Authors: Carta F. O.
Published: October 2009

Tests were conducted on a linear cascade of airfoils oscillating in pitch to measure the unsteady pressure response on selected blades along the leading edge plane of the cascade and over the chord of the center blade. The pressure data were reduced to Fourier coefficient form for direct comparison and were also processed to yield integrated loads and, particularly, the aerodynamic damping coefficient. In addition, results from two unsteady theories for cascaded blades with nonzero thickness and camber were compared with the experimental measurements. The three primary results that emerged from this investigation were: (a) from the leading edge plane blade data, the cascade was judged to be periodic in unsteady flow over the range of parameters tested, (b) as before, the interblade phase angle was found to be the single most important parameter affecting the stability of the oscillating cascade blades, and (c) the real blade theory and the experiment were in excellent agreement for the several cases chosen for comparison.
An Improved Method for Calculating Critical Speeds and Rotordynamic Stability of Turbomachinery
Authors: Murphy B. T. , Vance J. M.
Published: October 2009

A number of the computer programs for rotordynamic stability and critical speed prediction in common use during recent years have been based on the works of Myklestad, Prohl, and Lund. Programs of this type, called transfer matrix programs, employ complex variables when damping or cross-coupling are included in the model. Most use an iteration scheme which at times fails to converge with sufficient accuracy on some critical speeds, and has been known to completely miss critical speeds on occasion. It is shown in this paper that by rearranging the calculations performed in a transfer matrix program, one can derive the characteristic polynomial for a complex rotor-bearing system with no loss in generality. The modeling procedures are identical for the rotor and bearing/foundations, including the effects of gyroscopics, damping, and any or all destabilizing influences which are linearized in the usual manner. With the characteristic polynomial known, critical speeds can be estimated and stability predicted with greater efficiency and with no fear of missing any modes. Such a program has been written, and a complete comparison between the two types of programs is shown.
Comparison of Two- and Three-Dimensional Flow Computations With Laser Anemometer Measurements in a Transonic Compressor Rotor
Authors: Chima R. V. , Strazisar A. J.
Published: October 2009

Two-and three-dimensional inviscid solutions for the flow within a transonic axial compressor rotor at design speed are compared to laser anemometer measurements at maximum flow and near stall operating points. Computational details of the two-dimensional axisymmetric stream function solution and the three-dimensional full Euler solution are described. Upstream of the rotor, the two and three-dimensional solutions for radial distribution of relative Mach number and total pressure agree well with the data. Within the bow wave system and the blade row, the axisymmetric two-dimensional solution shows only qualitative agreement with the data.
RACER Conceptual Design
Authors: Halkola J. T. , Campbell A. H. , Jung D.
Published: October 2009

The Rankine Cycle Energy Recovery (or RACER) is an unfired waste heat recovery system designed for use aboard U.S. Navy gas turbine powered ships. The system converts waste heat from the exhaust of the main propulsion gas turbines into useful shaft horsepower and is currently planned for installation aboard the new DDG-51 class of ships. The design philosophy used in determining an overall system concept to minimize manning yet maximize availability, reliability and fuel savings is discussed. The paper also describes the trade-off analyses made to size the system in relation to overall fuel saving and gives a brief summary of the test programs to verify the system prior to ship installation.
The Feasibility of Water Injection Into the Turbine Coolant to Permit Gas Turbine Contingency Power for Helicopter Application
Authors: Van Fossen G. J.
Published: October 2009

A system which would allow a substantially increased output from a turboshaft engine for brief periods in emergency situations with little or no loss of turbine stress rupture life is proposed and studied analytically. The increased engine output is obtained by turbine overtemperature; however, the temperature of the compressor bleed air used for hot section cooling is lowered by injecting and evaporating water. This decrease in cooling air temperature can offset the effect of increased gas temperature and increased shaft speed and thus keep turbine blade stress rupture life constant. The analysis utilized the Navy NASA Engine Program or NNEP computer code to model the turboshaft engine in both design and off-design modes. This report is concerned with the effect of the proposed method of power augmentation on the engine cycle and turbine components. A simple cycle turboshaft engine with a 16:1 pressure ratio and a 1533 K (2760° R) turbine inlet temperature operating at sea level static conditions was studied to determine the possible power increase and the effect on turbine stress rupture life that could be expected using the proposed emergency cooling scheme. The analysis showed a 54 percent increase in output power can be achieved with no loss in gas generator turbine stress rupture life. A 231 K (415° F) rise in turbine inlet temperature is required for this level of augmentation. The required water flow rate was found to be 0.0109 kg water per kg of engine air flow. For a 4.474 MW (6000 shp) engine this would require 32.26 kg (71.13 lbm) of water for a 2.5 min transient. At this power level, approximately 25 percent of the uncooled power turbine life is used up in a 2 1/2-min transient. If the power turbine were cooled, this loss of stress-rupture life could be reduced to zero. Also presented in this report are the results of an analysis used to determine the length of time a ceramic thermal barrier coating would delay the temperature rise in hot parts during operation at elevated temperatures. It was hoped that the thermal barrier could be used as a scheme to allow increased engine output while maintaining the life of hot section parts during short overtemperature transients. The thermal barrier coating was shown to be ineffective in reducing blade metal temperature rise during a 2.5-min overtemperature.
Inertia Effects on the Dynamics of a Disk Levitated by Incompressible Laminar Fluid Flow
Authors: Warinner D. K. , Pearson J. T.
Published: October 2009

This paper develops a nonlinear ordinary differential equation (O.D.E.) of motion for a disk parallel to a flat plate and levitated by incompressible laminar flow of fluid supplied from a central orifice. The fluid’s inertia, reflected in high mass flow rates, is accounted for. The transient flow velocity and pressure field are found by iterative integration of the Navier-Stokes equation to determine the O.D.E. for the time-dependent height of the disk (or fluid film thickness). The film thickness is found by not only numerically integrating the O.D.E., but also by linearizing the equation to obtain a closed-form solution. The results of this combined squeeze-film, source-flow case compare favorably with experimental data presented which span cases from negligible inertia (viscous dominance) to cases of inertia dominance. Fortunately, the closed-form solution differs only slightly from the numerical solution; this provides relatively accurate expressions for the frequencies and damping coefficients in terms of the geometry, load (or weight of disk), mass flow rate, and the fluid properties.
Vectoring Exhaust Systems for STOL Tactical Aircraft
Authors: Tape R. F. , Hartill W. R. , Curry Lt. S. , Jones T. J.
Published: October 2009

An analytical study has been performed to investigate the performance and application of four exhaust nozzle concepts with the potential to enhance the short takeoff and landing capabilities of advanced tactical aircraft for the 1990s. The exhaust system concepts include side and rear exhaust thrust vectoring systems with axisymmetric and nonaxisymmetric nozzles. To investigate the application of the nozzle concepts, advanced tactical aircraft have been configured which will operate from 700 or 1000 feet fields. Four different propulsion system configurations were used, each producing glide slope equilibrium in a different way. The characteristics of these STOL aircraft are compared with those of a CTOL aircraft designed to perform the same mission. The results show that the short field performance can be achieved with little aircraft TOGW or LCC penalty. The study also identifies promising configurations for STOL tactical aircraft.
F-14 Aircraft and Propulsion Control Integration Evaluation
Authors: Davies W. J. , Hoelzer C. A. , Vizzini R. W.
Published: October 2009

Since 1976, the U.S. Navy in conjunction with Pratt and Whitney Aircraft (PWA) has been actively engaged in developing the technology base for on engine, dual redundant, fault tolerant, full authority digital electronic control (FADEC) systems with the capability of aircraft control integration for application to the next generation Navy aircraft. Navy contracts were awarded in 1981 to PWA and Grumman Aerospace Corporation (GAC) to identify the operational benefits of the F-14 Aircraft with a dual-redundant FADEC interfaced to an Advanced Fuel Management Systems (AFM) and integrated with the F-14 aircraft control system. This paper presents the FADEC/F-14 integration evaluation performed by PWA and discusses the benefits of the FADEC/F-14 integrated system. These include improvements in reliability, mission abort, survivability, maintainability, cruise fuel consumption, engine weight, diagnostics and fault recording, inlet and engine air flow matching and propulsion control accuracy.
LMFBR Operational and Experimental In-Core, Local-Fault Experience, Primarily With Oxide Fuel Elements
Authors: Warinner D. K.
Published: October 2009

Case-by-case reviews of selective world experience with severe local faults, particularly fuel failure and fuel degradation, are reviewed for two sodium-cooled thermal reactors, several LMFBRs, and LMFBR-fuels experiments. The review summarizes fuel-failure frequency and illustrates the results of the most damaging LMFBR local-fault experiences of the last twenty years, beginning with BR-5, and including DFR, BOR-60, BR2’s MFBS-and Mol-loops experiments, Fermi, KNK, Rapsodie, EBR-II, and Treat-D2. Local-fault accommodation is demonstrated and a need to more thoroughly investigate delayed-neutron and gaseous-fission-product signals is highlighted in view of uranate formation, observed blockages, and slow fuel-element failure-propagation.
The LMFBR Fuel-Design Environment for Endurance Testing, Primarily of Oxide Fuel Elements With Local Faults
Authors: Warinner D. K.
Published: October 2009

The U.S. Department of Energy LMFBR Lines-of-Assurance are briefly stated and local faults are given perspective with an historical review and definition to help define the constraints of LMFBR fuel-element designs. Local-fault-propagation (fuel-element-failure propagation and blockage propagation) perceptions are reviewed. Fuel pin designs and major LMFBR parameters affecting pin performance are summarized. The interpretation of failed-fuel data is aided by a discussion of the effects of nonprototypicalities. The fuel-pin endurances expected in the United States, USSR, France, UK, Japan, and West Germany are outlined. Finally, fuel-failure detection and location by delayed-neutron and gaseous-fission-product monitors are briefly discussed to better realize the operational limits.
Design Concept and Development of a Heavy-Duty Truck Diesel Engine for Better Fuel Economy
Authors: Kobayashi A. , Ozawa M. , Noda M. , Kikuchi K.
Published: October 2009

Due to the increasing price of fuel, demands for fuel economy of heavy-duty trucks become severer year by year, and many efforts, such as reduction of air drag of vehicle, optimization of transmission and engine performance, improvement of engine combustion, etc., have been taken to meet these demands. However, requirements for the reduction of fuel consumption are expected to become even more critical, so the authors have studied a new design concept for heavy duty truck diesel engines to satisfy these requirements. The basic idea for getting a fuel-economic engine is to make the engine as small as possible and also to apply higher boost turbocharging for obtaining a sufficiently high output. However, measures to improve the undesirable problems which conventional turbocharged engines possess, such as lack of acceleration response and low-speed torque, increase of thermal and mechanical loads, shortage of engine brake torque, poor cold start ability, etc., should also be pursued. A chassis-mounted air-to-air intercooler, inertia-charged air induction system, highly backward-curved impeller of turbocharger, electronically controlled fuel injection timing device, etc., have been applied. And a new design technique as well as new material and construction have also been applied. This engine was installed to a long-haul truck with a gross weight of around 20,000 kg (44,000 lbs) and got better fuel mileage, as expected.
Status of Design Code Work in Germany Concerning Materials and Structural Aspects for the Heat Exchanger Components of Advanced HTR’s
Authors: Schubert F. , Seehafer H. J. , Bodmann E.
Published: October 2009

A brief status report on the work concerning design codes for HTR components with service temperatures above 800°C is given. The evaluation of experimental test work and preliminary time-dependent design data are reviewed and some design analyses for an IHX concerning fatigue, creep buckling, and creep ratcheting are described as a basis for critical discussion of some features of ASME Code Case N 47.
LMFBR Steam Generator Materials Development at Westinghouse
Authors: Hebbar M. A. , Sessions C. E.
Published: October 2009

The impact of Materials and Processes (M and P) development activities at the Nuclear Components Division - Breeder Reactor Components Project of Westinghouse are described. Nine specific M and P programs have been performed over the past five years and the conclusions drawn from each are summarized herein. These engineering activities could be classified as component design, fabrication, and testing results. However, the discussion presented is from a materials engineer’s viewpoint as to how the previously proposed development tasks have answered existing questions about either design, manufacturing, or plant operation. The nine areas which are discussed include (i) double-wall tubing, (ii) tube-to-tubesheet welding, (iii) few tube model fabrication and testing, (iv) tube support plates, (v) shell welding, (vi) convoluted shell expansion joint, (vii) water chemistry and corrosion behavior, (viii) chemical cleaning, and (ix) surface contamination protection.
Thermal/Hydraulic Tests of Tube Supports in a Multitube Steam Generator Model
Authors: Vroom D. W. , Babcock D. A. , Cassell D. S.
Published: October 2009

The presence of tube supports in PWR steam generator tube bundles creates regions of restricted flow which may result in altered heat transfer effects and increased pressure drop. One heat transfer effect which can occur is localized vaporization or “dry out”. At higher heat flux levels this may result in a stable vapor blanket or an alternate wetting and drying occurring with an accompanying increase in the local tubewall surface temperature. A test program was conducted to determine the thermal/hydraulic conditions at the inception of the tubewall temperature excursion for selected tube support designs and to measure the pressure drop across the supports using a multitube steam generator model. Tests were performed on each of four tube supports over a broad range of shellside quality/subcooling conditions and pressures, temperatures, and mass flow rates that are prototypical of PWR steam generator operating conditions. Photographs and high-speed movies were taken of the flow both above and below the test piece.
Experimental Investigation on Denting in PWR Steam Generators: Causes and Corrective Actions
Authors: Nordmann F. , Pinard-Legry G. , Daret J. , Brunet J. P.
Published: October 2009

Denting studies have been undertaken in order to assess the influence of the most important parameters which could initiate corrosion of the carbon steel occurring in the tube-tube support plate crevices of some PWR steam generators. Tests have been carried out in model boilers where feedwater was polluted with sea or river water. Specific effects of chloride or sulfate and influence of oxygen content, magnetite addition and pH value were investigated. In magnetite prepacked crevices, denting is obtained within 1000 hrs for seawater pollution of 0.3 ppm chloride at the blowdown. In neutral chloride or in river water, denting is observed only with oxygen addition. Denting prevention is effective in the case of an on-line addition of phosphate, boric acid, or calcium hydroxide. For denting stopping, boric acid or calcium hydroxide is efficient even with a high seawater pollution. Soaks cannot stop denting if they are not followed by an on-line treatment (boric acid, calcium hydroxide). With quadrifoil holes, denting doesn’t occur. In very severe test conditions, 13 percent Cr steel can be corroded, but the corrosion rate is low and oxide morphology is different from that growing on carbon steel.
Shock Wave/Boundary Layer Interaction in Dry and Wet Transonic Steam
Authors: Evans N. A.
Published: October 2009

As part of the continuing technological advance towards the design of transonic steam turbine blades by analysis, rather than by experience based on time-consuming field testing, a series of experiments in a one-dimensional Laval nozzle was conducted to determine the nature of self-excited fluctuations due to shock wave/boundary layer interaction. Results in superheated steam flow showed peak-to-peak pressure fluctuations reaching 80 percent of the ideal across a normal shock wave, with a frequency spectrum having a fairly flat response to 150 Hz. Results in wet flow showed a distinctly different spectrum with decreased activity up to 200 Hz, but a shock wave interacting with incipient condensation near the nozzle throat produced additional broad spectral strength at 500 and 700 Hz. In addition, shock wave fluctuation in supercooled flow could trigger condensation in advance of the natural Wilson point.
Design of a Catalytic Combustor for Heavy-Duty Gas Turbines
Authors: Touchton G. L. , Szema L. C. , Cutrone M. B. , Cellamare R. , Vonkleinsmid W.
Published: October 2009

Laboratory tests of catalytic combustors with distillate fuel have achieved ultralow NOx formation at catalytic reactor exit temperatures and combustion efficiencies consistent with state-of-the-art gas turbine requirements. Concomitant with these features, however, are design limitations such as narrow turn-down range and unique reactor mounting requirements. This paper presents fully analyzed conceptual design solutions to these problems within the constraints of fixed geometry, full catalytic combustion over 80 percent of the turbine load range, and retrofit to an existing gas turbine. The combustor design incorporates (a) a gutter stabilized pilot burner downstream of the reactor for operation from ignition to full-speed no-load, (b) a segmented fuel-air preparation system for fuel staging of the reactor, (c) a reactor mounting system which accommodates thermal growth and start-up and shutdown transients, and (d) a graded cell reactor. These features were achieved while maintaining low reactor face velocities and system pressure drops.
Development of the Transpiration Air-Cooled Turbine for High-Temperature Dirty Gas Streams
Authors: Wolf J. , Moskowitz S.
Published: October 2009

Studies of combined cycle electic power plants have shown that increasing the firing temperature and pressure ratio of the gas turbine can substantially improve the specific power output of the gas turbine as well as the combined cycle plant efficiency. Clearly this is a direction in which we can proceed to conserve the world’s dwindling petroleum fuel supplies. Furthermore, tomorrow’s gas turbines must do more than operate at higher temperature; they will likely face an aggressive hot gas stream created by the combustion of heavier oils or coal-derived liquid or gaseous fuels. Extensive tests have been performed on two rotating turbine rigs, each with a transpiration air cooled turbine operating in the 2600 to 3000°F (1427 to 1649°C) temperature range at increasing levels of gas stream particulates and alkali metal salts to simulate operation on coal-derived fuel. Transpiration air cooling was shown to be effective in maintaining acceptable metal temperatures, and there was no evidence of corrosion, erosion, or deposition. The rate of transpiration skin cooling flow capacity exhibited a minor loss in the initial exposure to the particulate laden gas stream of less than 100 hours, but the flow reduction was commensurate with that produced by normal oxidation of the skin material at the operating temperatures of 1350°F (732°C). The data on skin permeability loss from both cascade and engine tests compared favorably with laboratory furnace oxidation skin specimens. To date, over 10,000 hr of furnace exposure has been conducted. Extrapolation of the data to 50,000 hr indicates the flow capacity loss would produce an acceptable 50°F (10°C) increase in skin operating temperature.
Erosion Pattern of Twisted Blades by Particle Laden Flows
Authors: Hamed A. , Fowler S.
Published: October 2009

This paper presents the results of a study to predict turbomachine blade erosion by particle laden flows. Using statistical methods, this work combines particle trajectory calculations with experimental erosion data to determine the erosion of blades. The results of the calculations are presented to show the different patterns of blade material removal distribution over the surface of twisted stator blades for different particle sizes.
Steam-Cooled Gas Turbine Casings, Struts, and Disks in a Reheat Gas Turbine Combined Cycle: Part I—Compressor and Combustor
Authors: Rice I. G.
Published: October 2009

High-cycle pressure-ratio (38–42) gas turbines being developed for future aircraft and, in turn, industrial applications impose more critical disk and casing cooling and thermal-expansion problems. Additional attention, therefore, is being focused on cooling and the proper selection of materials. Associated blade-tip clearance control of the high-pressure compressor and high-temperature turbine is critical for high performance. This paper relates to the use of extracted steam from a steam turbine as a coolant in a combined cycle to enhance material selection and to control expansion in such a manner that the cooling process increases combined-cycle efficiency, gas turbine output, and steam turbine output.
Simplified Mathematical Representations of Heavy-Duty Gas Turbines
Authors: Rowen W. I.
Published: October 2009

This paper provides simplified mathematical representations of heavy-duty gas turbines that are suitable for use in dynamic power system studies and in dynamic analyses of connected equipment. The full range of heavy-duty, single-shaft gas turbines, from 18 MW (24,000 HP) and 106 MW (142,000 HP), is covered, as well as both liquid and gas fuel systems, parallel and isolated operation, droop and isochronous governors, and the impact of both air- and hydrogen-cooled generators on the characteristics of the model. Alterations to the models, for the purpose of further simplification, are also discussed.
Conversion of a Heavy-Duty Industrial Gas Turbine to Combined Cycle
Authors: Leffler D. W. , Roberts B. S.
Published: October 2009

This paper discusses the evaluation, design, and operation of a combined-cycle plant for Bahamas Electricity Corporation in Nassau, Bahamas. The plant was designed to provide maximum fuel efficiency, satisfactorily operate to 40 percent load, and includes provisions for heavy oil firing in the gas turbine. The system was started up July, 1982 and has been in successful operation since then.
On the Transient Interaction of Centrifugal Compressors and Their Piping Systems
Authors: Sparks C. R.
Published: October 2009

The problems of surge and other low-frequency pulsation phenomena in centrifugal compressors are described in terms of both machine (head curve) characteristics and the flow impedance characteristics of its attached piping. Flow stability criteria are presented in terms of net modal damping, as the combination of piping acoustic damping and equivalent negative damping of the compressor in the surge region of its performance curve. Surge and instability frequencies are related to acoustic reactance of the piping system. Finally, theoretical concepts are verified both by electrical analog models and by field and laboratory data on real compressors. This paper provides some new and significant findings on the dynamic interaction of centrifugal compressors with piping systems and describes the basic phenomena underlying these interactions. Good agreement is shown between predicted and measured surge frequencies, and for those termed “piping resonance surge” produced by high flow offsets or flat spots in the head curve.
Effects of Anomalous Rotor Joints on Turbomachine Dynamics
Authors: Klompas N.
Published: October 2009

Mechanisms simulating rotor joint restoring moments different from the common axisymmetric elastic hinge are derived and their effects on the dynamics of a complete turbomachine are calculated by impressing equivalent perturbing moments. A mechanism for locking subsynchronous whirl to a fractional frequency is described and supporting experimental observations are discussed. Sample analysis shows the possibility of self-sustained synchronous whirl due to preload asymmetry.
An Investigation Into the Effect of Side-Plate Clearance in an Uncentralized Squeeze Film Damper
Authors: Cookson R. A. , Dainton L. J.
Published: October 2009

An experimental investigation has been carried out into the influence of side-plate flow restrictors on the performance of a squeeze film damper bearing. The experimental rig used was a flexible rotor with a disk positioned midway between two squeeze film damper bearings. One of the squeeze film dampers was fitted with side plates that could be adjusted and accurately located with respect to the squeeze film damper journal. It has been found that the influence of the side-plate clearance on the ability of the squeeze film damper to reduce the amplitude of the central disk can be considerable if the side-plate clearance is less than the radial clearance. As the side-plate clearance reduces towards zero, the effectiveness of the squeeze film damper diminishes until the amplitudes obtained are the same as those measured when the rolling-contact bearing is rigidly supported. An interesting type of precessing elliptical orbit was discovered for conditions where the “jump” phenomenon was operating.
An Advanced Radial-Component Industrial Turbine Engine
Authors: Mowill J. , Strom S.
Published: October 2009

The first engine of a new family of high performance, industrial radial turbines is presented. The new single-shaft, 1500-kW site rated KG3 is built upon extensive experience from the field proven KG2 of the same nominal power. The KG3 is being developed both as a simple cycle and recuperated engine providing specific fuel consumptions in the range of 0.29–0.19 kg/kW-hr (0.47–0.32 lbs/hp-hr). This engine makes use of a high specific speed, high pressure ratio centrifugal compressor combined with a very high tip speed uncooled radial turbine to obtain optimized aerodynamic matching. Several novel design features are described.
Gas Turbine Bucket Corrosion Protection Developments
Authors: Lindblad N. R. , Schilling W. F. , Aeschbacher H. J. , Knoll W. H.
Published: October 2009

This paper describes a joint General Electric/ARAMCO program for improving rotating gas turbine parts lives in desert environments with high concentrations of alkali salts and sulfur-containing fuels. A description of the environment is given along with a definition of the hot corrosion problem. A series of buckets coated with experimental or developmental coatings produced by a variety of processes such as pack cementation, physical vapor deposition, plasma spray and sheet claddings are described and results from actual field trials are discussed. Pt-Cr-Al pack cementation coatings were observed to perform well. Next generation overlay coatings of the MCr-AlY-type applied by plasma spraying electron beam and sheet cladding processes also performed well.
Application of Abrasive Coatings to Clearance Control in the Gas Turbine
Authors: Vogan J. W. , Stetson A. R.
Published: October 2009

Efficiency of a gas turbine is reduced by vane tip losses in the compressor section; also, vane tip/rotor rubs can produce catastrophic failure of a gas turbine engine. This paper describes a test rig and experimental data obtained evaluating abrasive coatings for clearance control between the vanes and the rotor in a gas turbine compressor. Plasma/flame sprayed oxides, carbides and bonded abrasives were tested under conditions duplicating those encountered in the compressor section. The effectiveness of the coatings in grinding away the vane tips to provide minimum clearance without damage to the vane or rotor was determined. Coatings with rough, sharp abrasive grains were most effective. The laboratory tests were confirmed in engine development tests and by application to a compressor rotor now in operation.
Design and Application of a Single Gas Turbine Matched with Two Tandem Driven Centrifugal Compressors
Authors: Wood D. W. , Reid R. G.
Published: October 2009

This paper deals with the design and application of a 29,000 bhp (21,625 KW) gas turbine-compressor unit to perform the duties of high pressure ratio/low volume (storage) and low pressure ratio/high volume (transmission). To achieve this wide range of requirements, a single gas turbine was matched with two tandem driven centrifugal compressors. The paper describes the considerations and the techniques used to select the gas turbine, compressor aerodynamic performance and match the gas turbine and compressors.
Application of Gas Turbine/Compressors in LNG Plants
Authors: Brown T. T. , Hubbard J. K.
Published: October 2009

The objective of this paper is to discuss key considerations associated with selection of Gas Turbine Driven LNG (Liquefied Natural Gas) Turbo Compressors. The selection of any compressor and the ultimate performance is greatly affected by the gas turbine driver chosen. The selection of gas turbine/compressor packages is even more critical when the compressor is to operate on refrigeration service such as in an LNG plant. The selection, performance and operation will be discussed for complete gas turbine compressor packages.
Design and Closed Loop Testing of High-Pressure Centrifugal Gas Compressors for the Suppression of Subsynchronous Vibration
Authors: Criqui A. F. , Wendt P. G.
Published: October 2009

The causative phenomena of subsynchronous vibration, or re-excitation of the critical speed of a rotor, are discussed. Two rotor systems designed to control this type of vibration are presented. One system employs tuned, oil film damper bearings while the other features a stiffened rotor geometry. Stability thresholds of each design are compared based on high-pressure closed loop testing.
Measured Effects of Flow Leakage on the Performance of the GT-225 Automotive Gas Turbine Engine
Authors: Matthews C. C.
Published: October 2009

A GT-225 regenerative gas turbine engine was used to obtain engine performance data with varied rates of simulated internal leakage. Regenerator hot surface rim and crossarm seal leaks as well as regenerator cold surface seal leaks were simulated. Instrumentation was included in external ducting to measure the leakage rates. Data were taken at three gasifier turbine speeds with turbine inlet temperature held constant by means of the variable power turbine nozzle and also with varied turbine inlet temperatures resulting from operation with the nozzle fixed at the design area. Component performance data were calculated from the engine measurements to determine the loss mechanisms associated with the leakage. The GT-225 was most sensitive to hot surface rim seal leakage, followed closely by the hot surface crossarm seal leakage, and then the cold surface leakage. Performance was degraded much more when turbine inlet temperature was fixed (by about a factor of three for specific fuel consumption) than for the fixed geometry mode. The effects of leakage became less severe as gasifier turbine speed was increased. The engine performance deterioration due simply to the flow bypass is compounded by induced losses in regenerator and compressor performance leading to very large changes in engine performance, e.g., specific fuel consumption increased up to 80 percent and power decreased as much as 40 percent with 8 percent additional leakage.
Application of Recuperative Gas Cycles with a Bypass Heat Generator to Solar Energy Power Plants
Authors: Tilliette Z. P. , Pierre B.
Published: October 2009

Gas cycles are being studied for solar energy power plants on account of the attractive prospects they offer for an efficient heat source utilization. By using a particular arrangement applicable to open or closed recuperative gas cycles, consisting of a heat generator partly bypassing the low pressure side of the recuperator, further improvements can be effected in gas turbine systems. They result in favorable conditions for power and high temperature heat cogeneration, for combined gas and steam cycles, and for flexible plant operation. Specific aspects of solar energy are investigated. They mainly concern variations in operating conditions, energy storage, energy conversion efficiency and combined cycles. Applications are made to open and closed cycle power plants. As the combination of a solar receiver with a fossil-fired auxiliary heat source is considered, fossil-fired power plants with an auxiliary solar heating are examined.
A Simple Solar Gas Turbine Plant
Authors: Kovats A.
Published: October 2009

The Solar powered gas turbine plant has a storage system which is also capable of supplying instant heat at short interruptions of sunshine by clouds. The storage tank is not under pressure and is built of inexpensive material.
Surge-Induced Structural Loads in Gas Turbines
Authors: Mazzawy R. S.
Published: October 2009

The axial flow compression system of a modern gas turbine engine normally delivers a large quantity of airflow at relatively high velocity. The sudden stoppage (and reversal) of this flow when an engine surges can result in structural loads in excess of steady state levels. These loads can be quite complex due to inherent asymmetry in the surge event. The increasing requirements for lighter weight engine structures, coupled with the higher pressure ratio cycles required for minimizing fuel consumption, make the accurate prediction of these loads an important part of the engine design process. This paper is aimed toward explaining the fluid mechanics of the surge phenomenon and its impact on engine structures. It offers relatively simple models for estimating surge-induced loads on various engine components. The basis for these models is an empirical correlation of surge-induced inlet overpressure based on engine pressure ratio and bypass ratio. An approximate estimate of the post-surge axial pressure distribution can be derived from this correlation by assuming that surge initiation occurs in the rear of the compression system.
The Effects of Some Design Parameters of an Isolated Rotor on Inlet Flow Distortions
Authors: Yocum A. M. , Henderson R. E.
Published: October 2009

A study of the effects of rotor-blade geometry, steady loading, and distortion wavelength on the distortion flow field upstream and downstream of an unstalled isolated rotor shows that the attenuation of the distortion as it passes through the rotor is a function of the blade stagger angle and the distortion-reduced frequency or the ratio of rotor blade spacing to the distortion wavelength s/l. Maximum attenuation occurs when s/l = 0.5 and increases with increasing stagger angle. Little influence of rotor incidence angle or steady loading was observed.
Conceptual Design of an 80,000-shp Fossil-Fired Closed-Cycle Helium Turbine Propulsion System for Naval Ship Applications
Authors: Shu Ho-Tien , Kuo S. C. , Horton T. L. O. , Fisher E. R.
Published: October 2009

A conceptual design was made of an 80,000-shp fossil-fired closed-cycle helium turbine system for naval propulsion applications. Various oil-fired heater and power conversion system configurations were investigated, and a reference system was selected based on a trade-off between the system performance and the component size and weight characteristics which would yield the maximum pay load capability for the ship type considered. The conceptual design of major components was made based on the parametric design results identified from a comprehensive computer program incorporating extensive past design experiences. The conceptual design drawing for the propulsion engine is presented, and a preliminary propulsion system layout applicable to a conceptual high-speed destroyer is shown. The analysis indicates that no severe integration problem is anticipated for this type propulsion engine for lightweight ship propulsion applications.
Viscous Flow Analysis in Mixed Flow Rotors
Authors: Khalil I. , Tabakoff W. , Hamed A.
Published: October 2009

A method for analyzing the viscous flow through turbomachine rotors is presented. The field analysis is based on the solution of the full Navier-Stokes equations over the rotor blade-to-blade stream channels. An Alternating-Direction-Implicit method is employed to carry out the necessary numerical integration of the elliptic governing equations. The flow analysis may be applied to various types of turbomachine rotors. Preliminarily, only the case of laminar flows are considered in this paper. The flow characteristics within the rotors of a radial inflow turbine and a radial bladed compressor are investigated over a wide range of operating conditions. Excellent results are obtained when compared with existing experimental data. The method of this analysis is quite general and can deal with wide range of applications. Possible modification of the present study to deal with turbulent flow cases are also identified.
Generalized Parameters for Selection of Turbines and Working Fluids for OTEC Power Systems
Authors: Rosard D. D.
Published: October 2009

The choice of working fluid has a significant impact on the size and design characteristics of turbines for closed cycle OTEC (Ocean Thermal Energy Conversion) power systems. This paper examines turbine sizes and speeds for various candidate working fluids. The turbine performance and design limits are strongly influenced by blade stress criteria which have been ignored by previous investigators. Illustrative design parameters are given for a turbine using ammonia and scaling parameters are listed to compare the power outputs of turbines using other fluids. The design of a turbine for open-cycle OTEC power systems is largely dictated by the very high specific volume of the exhaust steam at a pressure of about 0.14 psia. In order to minimize the cost of turbines and generators through economy of scale, it is desirable to maximize the power output of a single turbine, and this leads to very large diameters and blade lengths. This paper explores the considerations which influence the choice of turbine size, blade length, speed, power output and efficiency.
Some Dynamic and Time-Averaged Flow Measurements in a Turbine Rig
Authors: Krause L. N. , Fralick G. C.
Published: October 2009

Four types of sensors were used to make both dynamic and time-averaged flow measurements in a cold turbine rig to determine the magnitude of errors in time- averaged total-pressure measurement at a station 5 1/2 blade cords downstream from the rotor. The errors turned out to be negligible. The sensors and their intended use are discussed.
The Combined Reheat Gas Turbine/Steam Turbine Cycle: Part I—A Critical Analysis of the Combined Reheat Gas Turbine/Steam Turbine Cycle
Authors: Rice I. G.
Published: October 2009

The reheat gas turbine cycle combined with the steam turbine Rankine cycle holds new promise of appreciably increasing power plant thermal efficiency. Apparently the cycle has been overlooked and thus neglected through the years. Research and development is being directed towards other gas turbine areas because of the world energy crunch; and in order to focus needed technical attention to the reheat cycle, this paper is presented, using logic and practical background of heat recovery boilers, steam turbines, gas turbines and the process industry. A critical analysis is presented establishing parameters of efficiency, cycle pressure ratio, firing temperature and output. Using the data developed, an analysis of an actual gas generator, the second generation LM5000, is applied with unique approaches to show that an overall 50 percent efficiency power plant can be developed using today’s known techniques and established base-load firing temperatures.
The Combined Reheat Gas Turbine/Steam Turbine Cycle: Part II—The LM 5000 Gas Generator Applied to the Combined Reheat Gas Turbine/Steam Turbine Cycle
Authors: Rice I. G.
Published: October 2009

Part I presented an analysis of the simple and reheat gas turbine cycles and related these cycles to the combined gas turbine Rankine cycle. Part II uses the data developed in Part I and applies the second generation LM5000 to a combined cycle using a steam cycle with 1250 psig 900 FTT (8.62MPa and 482°C) steam conditions; then the reheat gas turbine is combined with a reheat steam turbine with steam conditions of 2400 psig and 1000/1000 FTT (16.55 MPa and 538/538° C). A unique arrangement of the superheater is discussed whereby part of the steam heat load is shifted to the reheat gas turbine to obtain a minimum heat recovery boiler stack temperature and a maximum cycle efficiency. This proposed power plant is projected to have a net cycle efficiency of 50 percent LHV when burning distillate fuel.
Mean Velocity and Decay Characteristics of the Guidevane and Stator Blade Wake of an Axial Flow Compressor
Authors: Lakshminarayana B. , Davino R.
Published: October 2009

Pure tone noise, blade row vibrations, and aerodynamic losses are phenomena which are influenced by stator and IGV blade wake production, decay, and interaction in an axial-flow compressor. The objective of this investigation is to develop a better understanding of the nature of stator and IGV blade wakes that are influenced by the presence of centrifugal forces due to flow curvature. A single sensor hot wire probe was employed to determine the three mean velocity components of stator and IGV wakes of a single stage compressor. These wake profiles indicated a varying decay rate of the tangential and axial wake velocity components and a wake profile similarity. An analysis, which predicts this trend, has been developed. The radial velocities are found to be appreciable in both IGV and the stator wakes. This wake data as well as the data from other sources are correlated in this paper. Appreciable static pressure gradient across the wake is found to exist near the trailing edge of both stator and IGV.
Influence of Freely Rotating Inlet Guide Vanes on the Return Flows and Stable Operating Range of an Axial Flow Fan
Authors: Venkatrayulu N. , Prithvi Raj D. , Narayanamurthi R. G.
Published: October 2009

This paper presents the results of experimental investigations on the three-dimensional flow and performance characteristics of a free vortex axial flow fan rotor, with a freely rotating and braked inlet guide vane row. The influences of axial distance between the inlet guide vane row and the rotor inlet, inlet guide vane setting angle and shape, partial omission of guide vanes at the hub and tip regions on the return flows have been studied and optimum axial distance and setting angle that will improve the useful operating range of the fan were determined. Use of freely rotating inlet guide vanes at high flow volumes and braked inlet guide vanes at low flow coefficients resulted in a reduction of return flows and an increase of the stable operating range of the axial fan rotor by more than 35 percent and this combination has yielded higher efficiencies as well in the extended region of stable operation.