Measurements of the Effects of Periodic Inflow Unsteadiness on the Aerodynamics of a Fishtail Diffuser

2002 ◽  
Author(s):  
M. I. Yaras ◽  
P. Orsi
Keyword(s):  
Velocity Field ◽  
Gas Turbine ◽  
Centrifugal Compressor ◽  
Operating Conditions ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Data Set ◽  
Flow Measurements ◽  
Measured Velocity ◽  
Substantial Impact

This study examines the effects of periodic inflow unsteadiness on the flow development through fishtail diffusers utilized on small gas-turbine engines. The periodic unsteadiness is due to the distortion of the flow in the peripheral direction at the exit of the centrifugal compressor impeller, caused by the jet-wake type of flow discharging from each passage of the impeller. The study consists of detailed measurements in a large-scale fishtail diffuser rig with a geometry that is typical of those used in small gas turbine engines. An unsteady-flow generator is used to approximate the type of diffuser-inflow conditions that exist at the exit of centrifugal compressor impellers. Detailed measurements of the transient velocity field have been performed at the inlet and at four cross-sectional planes throughout the diffuser using a miniature 4-wire probe. These measurements involve frequencies of inflow unsteadiness corresponding to design as well as off-design operating conditions. The measured velocity field is analyzed in a time-averaged sense and in the context of previously-performed steady-flow measurements. Results show significant effects of inflow unsteadiness at lower frequencies on the flow field in the diffuser, which translates into a substantial impact on the pressure recovery of the diffuser. In addition to providing insight into the physics of this flow, the experimental results presented here constitute a detailed and accurate data set that can be used to validate computational-fluid-dynamics codes for this application.

Effects of Periodic Inflow Unsteadiness on the Time-Averaged Velocity Field and Pressure Recovery of a Diffusing Bend With Strong Curvature

2004 ◽  
Vol 126 (2) ◽  
pp. 229-237 ◽  
Author(s):  
M. I. Yaras ◽  
P. Orsi
Keyword(s):  
Velocity Field ◽  
Gas Turbine ◽  
Large Scale ◽  
Cross Flow ◽  
Operating Conditions ◽  
Pressure Recovery ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Cross Sectional ◽  
Data Set

This study examines the effects of periodic inflow unsteadiness on the flow development through fishtail-shaped diffusers utilized on small gas-turbine engines. In this application, periodic unsteadiness is caused by a jet-wake type of flow discharging from each passage of the centrifugal compressor impeller. The study consists of detailed measurements in a large-scale fishtail diffuser rig with a geometry that is typical of those used in small gas-turbine engines. Measurements of the transient velocity field have been performed at five cross-sectional planes throughout the diffuser using a miniature hot-wire probe with four wires. These measurements involve frequencies of inflow unsteadiness corresponding to design as well as off-design operating conditions. Results indicate significant effects of inflow unsteadiness at the low end of the tested frequencies on the time-averaged streamwise and cross-flow velocity fields in the diffuser. This is shown to translate into a notable impact on the pressure recovery. In addition to providing insight into the physics of this flow, the experimental results presented here constitute a detailed and accurate data set that can be used to validate computational-fluid-dynamics algorithms for this type of flow.

Thermal Tip Clearance Control for Centrifugal Compressor of an APU Engine

1994 ◽  
Vol 116 (4) ◽  
pp. 629-634 ◽  
Author(s):  
G. Eisenlohr ◽  
H. Chladek
Keyword(s):  
Gas Turbine ◽  
Centrifugal Compressor ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Qualitative Description ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Turbine Engine ◽  
Design Calculations ◽  
Clearance Control

To master today’s demand for efficiency and compactness of centrifugal compressor components for small gas turbine engines the main attention must not only be given to the aerodynamic design of the impeller and diffuser components, but also to the installation situation of the surrounding parts. A vital aspect is the tip clearance control between impeller and shroud casing over the total operating range. Using the radial compressor for a small gas turbine engine, developed at BMW Rolls-Royce, the importance of tip clearance control is demonstrated. The possibilities for influencing and optimizing passive tip clearance control by design features are described; transient expansion processes must be considered when using a thermal tip clearance control. The results of the design calculations are compared with the results on the test stand and the engine itself. An effort is made to find a qualitative influence of tip clearance to the engine power output at operating conditions. This qualitative description is substantiated by test results with different tip clearances at the compressor teststand.

Fuel Flexibility in LM2500 and LM6000 Dry Low Emission Engines

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
John Blouch ◽  
Hejie Li ◽  
Mark Mueller ◽  
Richard Hook
Keyword(s):  
Gas Turbine ◽  
Operating Conditions ◽  
Inert Gases ◽  
Effect Of Temperature ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Kinetics Analysis ◽  
Fuel Flexibility ◽  
Low Emission ◽  
Commercial Operation

The LM2500 and LM6000 dry-low-emissions aeroderivative gas turbine engines have been in commercial service for 15 years and have accumulated nearly 10 × 106 hours of commercial operation. The majority of these engines utilize pipeline quality natural gas predominantly comprised of methane. There is; however, increasing interest in nonstandard fuels that contain varying levels of higher hydrocarbon species and/or inert gases. This paper reports on the demonstrated operability of LM2500 and LM6000 DLE engines with nonstandard fuels. In particular, rig tests at engine conditions were performed to demonstrate the robustness of the dual-annular counter-rotating swirlers premixer design, relative to flameholding with fuels containing high ethane, propane, and N2 concentrations. These experiments, which test the ability of the hardware to shed a flame introduced into the premixing region, have been used to expand the quoting limits for LM2500 and LM6000 gas turbine engines to elevated C2+ levels. In addition, chemical kinetics analysis was performed to understand the effect of temperature, pressure, and fuel compositions on flameholding. Test data for different fuels and operating conditions were successfully correlated with Damkohler number.

Computational Investigation on Centrifugal Compressor Performance at Various Altitudes

2011 ◽  
Vol 230-232 ◽  
pp. 1123-1128
Author(s):  
Yu Wang ◽  
Zhen Luo
Keyword(s):  
Gas Turbine ◽  
Centrifugal Compressor ◽  
Cfd Simulation ◽  
Numerical Solutions ◽  
Weight Ratio ◽  
Critical Factor ◽  
Computational Method ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Ambient Temperatures

Small gas turbine engines have been considered as a potential and popular mean of propulsion for Unmanned Aerial Vehicles (UAV). With the advantage of high thrust/power-to-weight-ratio from these engines, small aircraft can have larger payload allowance and higher altitude capability. However, at present, these gas turbine engines are not mature enough to perform critical mission for UAV. To be used for such critical mission, these gas turbine engines need a better reliability, efficiency and endurance. The capability of the engine to work efficiently in conditions at different altitude with the variant of air density is a critical factor related to higher operational ceiling. Hence this work aims to present a Computational Fluid Dynamics (CFD) simulation approach focusing on centrifugal compressors which are applied to turbo machines. A computational method is developed for studying the performance of small gas turbine engines over a range of altitude and ambient temperatures under different engine rates, and a centrifugal compressor simulation model is generated by using CFD techniques. Through numerical solutions obtained for different mesh sets the finest mesh of the model was determined. The performance curves obtained by the CFD simulation has been compared with the results obtained from the analytical method.

Fuel Flexibility in LM2500 and LM6000 Dry Low Emission Engines

2011 ◽  
Author(s):  
John Blouch ◽  
Hejie Li ◽  
Mark Mueller ◽  
Richard Hook
Keyword(s):  
Gas Turbine ◽  
Operating Conditions ◽  
Inert Gases ◽  
Effect Of Temperature ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Kinetics Analysis ◽  
Fuel Flexibility ◽  
Low Emission ◽  
Commercial Operation

The LM2500 and LM6000 dry-low-emissions (DLE) aeroderivative gas turbine engines have been in commercial service for 15 years and have accumulated nearly 10 million hours of commercial operation. The majority of these engines utilize pipeline quality natural gas predominantly comprised of methane. There is, however, increasing interest in nonstandard fuels that contain varying levels of higher hydrocarbon species and/or inert gases. This paper reports on the demonstrated operability of LM2500 and LM6000 DLE engines with nonstandard fuels. In particular, rig tests at engine conditions were performed to demonstrate the robustness of the dual-annular counter-rotating swirlers (DACRS) premixer design, relative to flameholding with fuels containing high ethane, propane, and N2 concentrations. These experiments, which test the ability of the hardware to shed a flame introduced into the premixing region, have been used to expand the quoting limits for LM2500 and LM6000 gas turbine engines to elevated C2+ levels. In addition, chemical kinetics analysis was performed to understand the effect of temperature, pressure, and fuel compositions on flameholding. Test data for different fuels and operating conditions were successfully correlated with Damkohler number.

scholarly journals Application of the vacuum casting technology in the production of small-size gas turbine engine blade machines

2021 ◽  
Vol 20 (3) ◽  
pp. 152-159
Author(s):  
A. M. Faramazyan ◽  
S. S. Remchukov ◽  
I. V. Demidyuk
Keyword(s):  
Gas Turbine ◽  
Centrifugal Compressor ◽  
Gas Turbine Engine ◽  
Shrinkage Porosity ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Vacuum Casting ◽  
Turbine Engine ◽  
Design Values ◽  
The Cost

The application of casting technologies in the production of parts and assemblies of small-size gas turbine engines is justified in the paper. The technology of vacuum casting in gypsum molds was tested during the production of an experimental centrifugal compressor of a small-size gas turbine engine. On the basis of a 3D model of the designed centrifugal compressor, computational studies of vacuum casting were carried out and rational parameters of the technological process were determined. Prototypes of the developed centrifugal compressor of a small-size gas turbine engine were made. The results of calculations and the performed technological experiment confirmed the fill rate of the gating form and the absence of short pour. The distribution of shrinkage porosity and cavities corresponds to the design values and is concentrated in the central part of the casting that is subjected to subsequent machining. The area of the blades, disc and sleeve is formed without defects. The use of casting technologies in the production of parts and assemblies of small-size gas turbine engines assures the required quality with a comparatively low price of the finished product, making it possible to achieve the balance between the cost of the technology and the quality of the product made according to this technology.

scholarly journals On the effect of the meridional contour shape on the power characteristics of a centrifugal compressor wheel

2020 ◽  
Vol 2020 (3) ◽  
pp. 12-17
Author(s):  
Yu.A. Kvasha ◽  
◽  
N.A. Zinevych ◽  
Keyword(s):  
Gas Turbine ◽  
Centrifugal Compressor ◽  
Computational Study ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Compressor Wheel ◽  
Power Characteristics ◽  
Contour Shape ◽  
Wide Range ◽  
Uniformly Distributed Sequence

This work is concerned with the development of approaches to the optimal aerodynamic design of centrifugal compressor wheels, which is due to the use of centrifugal stages in compressors of modern aircraft gas turbine engines and power plants. The aim of this work is a computational study of the effect of the meridional contour shape of a centrifugal compressor wheel on its power characteristics. The basic method is a numerical simulation of 3D turbulent gas flows in centrifugal wheels on the basis of the complete averaged Navier¬–Stokes equations and a two-parameter turbulence model. The computational study features: varying the shape of the hub and tip part of the meridional contour over a wide range, formulating quality criteria as the mean integral values of the wheel power characteristics over the operating range of the air flow rate through the wheel, and a systematic scan of the independent variable range at points that form a uniformly distributed sequence. As a result of multiparameter calculations, it was shown that in the case of a flow without separation in the blade channels of a wheel with a given starting shape of the meridional contour, varying that shape has an insignificant effect on the wheel power characteristics. It is pointed out that in similar cases it seems to be advisable to aerodynamically improve centrifugal wheels by varying the shape of their blades in the circumferential direction rather than in the meridional plane. This conclusion was made using rather a “coarse” computational grid, which, however, retains the sensitivity of the computed results to a variation in the centrifugal wheel geometry. On the whole, this work clarifies ways of further aerodynamic improvement of centrifugal compressor impellers in cases where the starting centrifugal wheel is a well-designed wheel with a flow without separation in the blade channels. The results obtained may be used in the aerodynamic optimization of centrifugal stages of aircraft gas turbine engines.

scholarly journals Approaches to the Prevaporized-Premixed Combustor Concept for Gas Turbines

1975 ◽  
Author(s):  
L. J. Spadaccini ◽  
E. J. Szetela
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Bluff Body ◽  
Porous Plate ◽  
Operating Conditions ◽  
Fuel Oil ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Operational Conditions ◽  
Lean Combustion

An experimental investigation was performed to evaluate a combustor concept which is applicable to gas turbine engines and is believed to offer valuable pollution control advantages relative to the conventional liquid-fuel-spray approach. It involves fuel prevaporization, premixing and lean combustion and may be applied to the design of combustors for aircraft, industrial or automotive powerplants. Two types of bluff-body flameholders, viz. porous-plate and drilled-plate, were evaluated for use as flame stabilizers within the combustor. Tests were conducted under sets of steady-state operational conditions corresponding, respectively, to applications in a low-pressure regenerative-cycle and high-pressure nonregenerative-cycle automobile gas turbine engines. The data acquired can be used to design gas turbine combustors having predicted performance characteristics which are better than those required to meet the most stringent automobile emissions regulations of the Federal “Clean Air Act.” Fuel prevaporization can be accomplished either externally, prior to admission into the engine airstream, or internally by the airstream itself. In support of the prevaporization concept, the feasibility of vaporizing No 2 fuel oil in a heat exchanger which is external to the engine was investigated. Tests conducted at representative operating conditions indicated that a deposit of 0.01 0-in. thickness was collected on the vaporizer wall after 50 hr of operation. A much shorter period of cleaning with hot air was sufficient to remove the deposit.

Prediction of CO Emission Index for Aviation Gas Turbine Combustor Using Flamelet Generated Manifold Combustion Model

2021 ◽  
Author(s):  
Saurabh Patwardhan ◽  
Pravin Nakod ◽  
Stefano Orsino ◽  
Rakesh Yadav ◽  
Fang Xu ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Liquid Fuel ◽  
Operating Conditions ◽  
Turbine Engines ◽  
Combustion Model ◽  
Gas Turbine Engines ◽  
Gas Turbine Combustor ◽  
Flamelet Generated Manifold ◽  
Emission Index ◽  
Co Emission

Abstract Carbon monoxide (CO) has been identified as one of the regulated pollutants and gas turbine manufacturers target to reduce the CO emission from their gas turbine engines. CO forms primarily when carbonous fuels are not burnt completely, or products of combustion are quenched before completing the combustion. Numerical simulations are effective tools that allow a better understanding of the mechanisms of CO formation in gas turbine engines and are useful in evaluating the effect of different parameters like swirl, fuel atomization, mixing etc. on the overall CO emission for different engine conditions like idle, cruise, approach and take off. In this paper, a thorough assessment of flamelet generated manifold (FGM) combustion model is carried out to predict the qualitative variation and magnitude of CO emission index with the different configurations of a Honeywell test combustor operating with liquid fuel under idle condition, which is the more critical engine condition for CO emission. The different designs of the test combustor are configured in such a way that they yield different levels of CO and hence are ideal to test the accuracy of the combustion model. Large eddy simulation (LES) method is used for capturing the turbulence accurately along with the FGM combustion model that is computationally economical compared to the detailed/reduced chemistry modeling using finite rate combustion model. Liquid fuel spray breakup is modeled using stochastic secondary droplet (SSD) model. Four different configurations of the aviation gas turbine combustor are studied in this work referring to earlier work by Xu et al. [1]. It is shown that the FGM model can predict CO trends accurately. The other global parameters like exit temperature, NOx emissions, pattern factor also show reasonable agreement with the test data. The sensitivity of the CO prediction to the liquid fuel droplet breakup model parameters is also studied in this work. Although the trend of CO variation is captured for different values of breakup parameters, the absolute magnitude of CO emission index differs significantly with the change in the values of breakup parameters suggesting that the spray has a larger impact on the quantitative prediction of CO emission. An accurate prediction of CO trends at idle conditions using FGM model extends the applicability of FGM model to predict different engine operating conditions for different performance criteria accurately.

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