The Predicted and Measured Effects of Increasing Back Pressure on the Performance of a Turboshaft Engine

2010 ◽  
Author(s):  
Marco S. Attia ◽  
Richard W. Eustace ◽  
Shane C. Favaloro
Keyword(s):  
Power Output ◽  
Engine Performance ◽  
Sensitivity Study ◽  
Test Facility ◽  
Inlet Temperature ◽  
Static Test ◽  
Tail Pipe ◽  
Fuel Flow ◽  
Power Turbine ◽  
Turboshaft Engine

This paper presents a comparison between the predicted effect of an increase in backpressure on a turboshaft helicopter engine and the actual results measured in an experimental test program. A generic engine performance program was used to perform a sensitivity study to identify the effect of increases in power turbine exit pressure (backpressure) on other engine performance parameters. The analysis showed that as the backpressure increases the engine increases fuel flow to produce a constant shaft torque (or horsepower), until the maximum power turbine entry temperature is reached. Once this occurs, fuel flow can no longer increase and thus further increases in backpressure cause a decrease in output torque. These predicted results are then compared with the actual effect as measured on a T55-GA-714A engine in a static test facility. The tests involved replacing the standard engine tail pipe with one of three shorter stub ducts which increased the backpressure by employing straight and convergent flow passages instead of the divergent passage on the standard tail pipe. The test-cell data identified that the stub ducts increase specific fuel consumption by between 0.016 and 0.039 lb/hr/hp, while the turbine inlet temperature increased by up to 108 deg F. This temperature increase means that the power output will become turbine temperature limited at a lower ambient temperature than would otherwise occur. Results showed that when temperature limiting exists the power output will be reduced by between 115 and 400 SHP depending on the choice of stub duct.

Heat transfer characteristic modelling and the effect of operating conditions on re-cooled cycle for a scramjet

2011 ◽  
Vol 115 (1164) ◽  
pp. 83-90 ◽  
Author(s):  
W. Bao ◽  
J. Qin ◽  
W. X. Zhou
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Transfer Characteristic ◽  
Cooling Capacity ◽  
Sensitivity Study ◽  
Performance Model ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Fuel Flow ◽  
Temperature And Pressure

Abstract A re-cooled cycle has been proposed for a regeneratively cooled scramjet to reduce the hydrogen fuel flow for cooling. Upon the completion of the first cooling, fuel can be used for secondary cooling by transferring the enthalpy from fuel to work. Fuel heat sink (cooling capacity) is thus repeatedly used and fuel heat sink is indirectly increased. Instead of carrying excess fuel for cooling or seeking for any new coolant, the cooling fuel flow is reduced, and fuel onboard is adequate to satisfy the cooling requirement for the whole hypersonic vehicle. A performance model considering flow and heat transfer is build. A model sensitivity study of inlet temperature and pressure reveals that, for given exterior heating condition and cooling panel size, fuel heat sink can be obviously increased at moderate inlet temperature and pressure. Simultaneously the low-temperature heat transfer deterioration and Mach number constrains can also be avoided.

scholarly journals The Effect of Compressor Rotor Tip Crops on Turboshaft Engine Performance

1992 ◽  
Author(s):  
Peter C. Frith
Keyword(s):  
Experimental Study ◽  
Engine Performance ◽  
Tip Clearance ◽  
Stability Margins ◽  
Compressor Rotor ◽  
Power Turbine ◽  
Normal Production ◽  
Turboshaft Engine ◽  
Engine Condition ◽  
Steady State Performance

The results from an experimental study into the effect of compressor rotor tip clearance changes on the steady-state performance and stability margins of a free-power turbine turboshaft engine are presented and discussed. This work was directed at the development of methods to diagnose engine condition from gas path measurements. It was found that the normal production suite of engine instrumentation was able to measure the deterioration in engine performance due to the implanted compressor degradation and the resultant deviations in the measured parameters from their respective nominal baselines do provide useful indicators of engine condition.

scholarly journals The Feasibility of Water Injection Into the Turbine Coolant to Permit Gas Turbine Contingency Power for Helicopter Application

1983 ◽  
Vol 105 (3) ◽  
pp. 635-642 ◽  
Author(s):  
G. J. Van Fossen
Keyword(s):  
Temperature Rise ◽  
Rupture Life ◽  
Stress Rupture ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Stress Rupture Life ◽  
Barrier Coating ◽  
Power Turbine ◽  
Turboshaft Engine

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.

Performance of a Turboshaft Engine for Helicopter Applications Operating at Variable Shaft Speed

2012 ◽  
Author(s):  
Gianluigi Alberto Misté ◽  
Ernesto Benini
Keyword(s):  
Steady State ◽  
Engine Performance ◽  
Engine Fuel ◽  
Main Rotor ◽  
Steady State Condition ◽  
Power Turbine ◽  
Steady State Model ◽  
Optimization Routine ◽  
Turboshaft Engine ◽  
The Impact

An off-design steady state model of a generic turboshaft engine has been implemented to assess the influence of variable free power turbine (FPT) rotational speed on overall engine performance, with particular emphasis on helicopter applications. To this purpose, three off-design flight conditions were simulated and engine performance obtained with different FTP rotational speeds were compared. In this way, the impact on engine performance of a particular speed requested from the main helicopter rotor could be evaluated. Furthermore, an optimization routine was developed to find the optimal FPT speed which minimizes the engine specific fuel consumption (SFC) for each off-design steady state condition. The usual running line obtained with constant design FPT speed is compared with the optimized one. The results of the simulations are presented and discussed in detail. As a final simulation, the main rotor speed Ω required to minimize the engine fuel mass flow was estimated taking into account the different requirements of the main rotor and the turboshaft engine.

Design and Development of the Inter-Turbine Structure and Power Turbine for MTR390-E Turboshaft Engine

2013 ◽  
Author(s):  
Pedro de la Calzada ◽  
Miguel A. Villanueva ◽  
Jorge Parra ◽  
Juan I. Ruiz-Gopegui
Keyword(s):  
Suction Side ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Design And Development ◽  
Power Turbine ◽  
Similar Materials ◽  
Mach Numbers ◽  
Turboshaft Engine ◽  
Two Stages ◽  
Tip Shroud

The MTR390-E is a turboshaft engine of 1000 kW class developed for the TIGER European helicopter. The project was launched back in 2004 and was certified in 2011. The engine is based on the previous MTR390-2C engine but redesigned for 14% more power at high and hot conditions. ITP is the design authority of the inter-turbine duct (ITD) and structure (IC) and the two stages Power Turbine (PT) as part of the MTRI European consortium (MTU, Turbomeca, RR, ITP) for the design and development of the Enhanced engine. The requirement of higher power, while maintaining the physical envelope of the engine for avoiding changes in the helicopter, led to higher mass flow and turbine inlet temperature. Consequently, the Mach number along the ITD and the PT was increased. A local increase in the flowpath around the area of the ITD and the NGV1 maximum thickness is introduced to avoid high peak Mach numbers and to reduce the flow diffusion. The PT aerofoils feature higher flow velocities leading to transonic Mach numbers at the suction side. The increase in temperature drove the introduction of internal cooling on the ITD and the NGV1 to maintain similar materials while avoiding risk of melting at Super Emergency Conditions (SUP). Due to the high shaft rotation speed and high operating temperatures the blades are subject to very high mechanical demanding conditions. Single crystal materials are used in both stages where also tip shroud cut outs were introduced to reduce centrifugal stresses. Life requirements were met in both statics and rotating parts. A complete development test plan was performed to achieve certification and qualification with 7 development engines and 4 flight proto engines. Performance was demonstrated at sea level and altitude conditions. Successful mechanical condition of parts was obtained after the 150-hrs Type Test plus additional SUP shots. Also good conditions were obtained after sand ingestion test. Good mechanical robustness was proved all along the development programme.

scholarly journals Determination of performance and parameters for turboprop and turboshaft engine for modification through change of gas temperature before turbine

2006 ◽  
Vol 127 (4) ◽  
pp. 34-43
Author(s):  
Stanisław ANTAS
Keyword(s):  
Engine Performance ◽  
Experimental Tests ◽  
Gas Temperature ◽  
Power Turbine ◽  
Methods Of Evaluation ◽  
Modification Method ◽  
Turboshaft Engine ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

The article presents the analysis of a commonly used performance modification method for turboprop and turboshaft engines with a free power turbine. The description of analytical and numerical methods of evaluation for a change of parameters and geometry of turbine assemblies are presented. There are also given the basic methods of changing throat area of turbine nozzle guide vanes and its influence on engine performance. The calculation methods are verified by experimental tests run by WSK “PZL-Rzeszów” S.A.

The Effect of Compressor Rotor Tip Crops on Turboshaft Engine Performance

1994 ◽  
Vol 116 (1) ◽  
pp. 184-189 ◽  
Author(s):  
P. C. Frith
Keyword(s):  
Experimental Study ◽  
Engine Performance ◽  
Tip Clearance ◽  
Stability Margins ◽  
Compressor Rotor ◽  
Power Turbine ◽  
Normal Production ◽  
Turboshaft Engine ◽  
Engine Condition ◽  
Steady State Performance

The results from an experimental study into the effect of compressor rotor tip clearance changes on the steady-state performance and stability margins of a free-power turbine turboshaft engine are presented and discussed. This work was directed at the development of methods to diagnose engine condition from gas path measurements. It was found that the normal production suite of engine instrumentation was able to measure the deterioration in engine performance due to the implanted compressor degradation and the resultant deviations in the measured parameters from their respective nominal baselines do provide useful indicators of engine condition.

scholarly journals Development of Reheat Combustor-Power Turbine Package

1991 ◽  
Author(s):  
M. Nakhamkin ◽  
E. C. Swensen ◽  
Arthur Cohn
Keyword(s):  
Gas Turbine ◽  
Power Output ◽  
Lower Cost ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Gas Generator ◽  
Turbine Inlet Temperature ◽  
Power Turbine ◽  
Gas Generators ◽  
Cycle Efficiency

This paper describes the first phase of an intended project to develop a reheat combustor-power turbine (RCPT) package which when added to an aircraft derivative gas generator would produce a commercially attractive reheat gas turbine for combined cycle and cogeneration applications. This first phase includes the identification of gas generators and establishes the relative merits of the RCPT package at various inlet temperatures based upon evaluated benefits. Our calculations show that in combined cycle application with the RCPT at an easily feasible power turbine inlet temperature of 1700°F, the steam flow increases by approximately 2.5 times, the combined cycle power by about 30%, and the combined cycle efficiency by about 5% compared to an unfired aeroderivative combined cycle. Compared to the duct fired combined cycle with the same power output, the efficiency increases by approximately 7.5%, leading to a lower cost of electricity of about 10 per cent for the economic assumptions of the study.

scholarly journals The Part-Load Performance of a Gas Turbine Engine With Two Turbines Working in Parallel

1986 ◽  
Author(s):  
Yousef S. H. Najjar ◽  
Taha K. Aldoss
Keyword(s):  
Gas Turbine ◽  
Power Output ◽  
Pressure Ratio ◽  
Gas Turbine Engine ◽  
Inlet Temperature ◽  
Combustion Chambers ◽  
Turbine Engine ◽  
Combustion Gases ◽  
Power Turbine ◽  
In Series

To reduce the inefficiency and the drawbacks incurred by reheat in a gas turbine engine with the two turbines in series, a parallel arrangement is investigated. The combustion gases expand to atmospheric pressure in each turbine. One of the turbines drives the compressor to which it is mechanically coupled while the other develops the power output of the plant. Two methods of control for the reduction of power are considered: a) Varying the fuel supply to the combustion chambers so that the inlet temperature to the turbine driving the compressor is constant, while the inlet temperature to the power turbine is reduced. b) Reducing both temperatures while keeping them equal. The effects of turbines inlet temperatures, pressure ratio and pressure loss in combustion chambers on the cycle efficiency and power output are studied and a sensitivity analysis is carried out, with the aid of a specially constructed computer program. The first method of control proved to be superior.

scholarly journals Jet A and Propane gas combustion in a turboshaft engine: performance and emissions reductions

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Ali Hasan ◽  
Oskar J. Haidn
Keyword(s):  
Combustion Process ◽  
Engine Performance ◽  
Emissions Reductions ◽  
Gas Combustion ◽  
Liquid Petroleum Gas ◽  
Performance And Emissions ◽  
Air Mixing ◽  
Turboshaft Engine ◽  
Engine Performance And Emissions ◽  
Lower Carbon

AbstractThe Paris Agreement has highlighted the need in reducing carbon emissions. Attempts in using lower carbon fuels such as Propane gas have seen limited success, mainly due to liquid petroleum gas tanks structural/size limitations. A compromised solution is presented, by combusting Jet A fuel with a small fraction of Propane gas. Propane gas with its relatively faster overall igniting time, expedites the combustion process. Computational fluid dynamics software was used to demonstrate this solution, with results validated against physical engine data. Jet A fuel was combusted with different Propane gas dosing fractions. Results demonstrated that depending on specific propane gas dosing fractions emission reductions in ppm are; NOx from 84 to 41, CO2 from less than 18,372 to less than 15,865, escaping unburned fuels dropped from 11.4 (just Jet A) to 6.26e-2 (with a 0.2 fraction of Propane gas). Soot and CO increased, this is due to current combustion chamber air mixing design.

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