scholarly journals Analysis of a Three-Dimensional, High Pressure Ratio Scramjet Inlet with Variable Internal Contraction

2012 ◽  
Author(s):  
Oliver Hohn ◽  
Ali Guelhan
Keyword(s):  
High Pressure ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
High Pressure Ratio

Experimental and Computational Investigation of the Time-Averaged and Time-Resolved Pressure Loading on a Vaneless Counter-Rotating Turbine

2000 ◽  
Author(s):  
C. W. Haldeman ◽  
M. G. Dunn ◽  
R. S. Abhari ◽  
P. D. Johnson ◽  
X. A. Montesdeoca
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Low Pressure ◽  
Navier Stokes ◽  
Experimental Program ◽  
Time Resolved ◽  
Design Point ◽  
High Pressure Ratio

The experimental program reported here was executed using full-scale vaneless counter-rotating engine hardware operating at nondimensionally scaled aerodynamic design point conditions. Measurements were obtained for three different pressure ratio values: design point, low pressure ratio, and high pressure ratio. For brevity, only the design point data will be presented in this paper. Time-averaged and time-resolved surface pressures on the high pressure turbine (HPT) vane, HPT blade, and low pressure turbine (LPT) blades are presented. Additionally, three-dimensional (3D) Navier-Stokes computational fluid dynamics (CFD) predictions are presented for comparison with experimental data. The results presented show that the predictions qualitatively capture the flowfield physics, but require some additional calibration to fully match experimental data quantitatively.

The Use of the 3D-Viscous Codes in the Analysis of High Speed High Pressure Ratio Centrifugal Impellers

2000 ◽  
Author(s):  
Tarek Mekhail ◽  
Du Zhao Hui ◽  
Chen Han Ping ◽  
Willem Janson
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Internal Flow ◽  
Tip Clearance ◽  
Centrifugal Impeller ◽  
Field Calculation ◽  
High Pressure Ratio ◽  
Industrial Gas Turbine

Abstract The flow inside a centrifugal impeller has various complex three dimensional phenomena (flow separation, jet-wake structure, shock wave, etc.). In this study, the internal flow field calculation of Samsung, high pressure ratio, high speed, centrifugal impeller with splitter blades is obtained by commercially available CFX-Tascflow code with CFX-Turbogrid for grid generation. The results are compared to that obtained previously by Denton and Dawes codes. The impeller is used in the first stage centrifugal compressor of an industrial gas turbine. The CFX-Tascflow results showed some differences Mach number contours. Also, the calculations are performed for Krain’s backswept impeller and the results are compared to the experimental measurements. Simulation of tip clearance has been done and the results were in a good agreement with the previous experiments.

Numerical Study on the Effects of Blade Lean on High-Pressure Centrifugal Impeller Performance

2011 ◽  
Author(s):  
JongSik Oh ◽  
Charles W. Buckley ◽  
Giri L. Agrawal
Keyword(s):  
High Pressure ◽  
Degrees Of Freedom ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Internal Flow ◽  
Secondary Flows ◽  
Centrifugal Impeller ◽  
High Pressure Ratio

Blade lean and sweep are additional degrees of freedom for the three dimensional blade design. When compared to blade sweep, the influence of blade lean on the performance is not extensively described in the public literature. The effects of blade lean on the aerodynamic performance of a high-pressure ratio centrifugal impeller were investigated using a CFD (Computational Fluid Dynamics) approach. For total of 15 variations of blade lean given at the impeller inlet and outlet, while blade angles at the impeller inlet and outlet were unchanged, numerical solutions of the impeller with a vaneless diffuser were obtained at the design speed from a maximum choke flow to a minimum flow available. Compressor performance maps were generated to compare overall characteristics, and details of internal flow structure at 5 different quasi-orthogonal planes were investigated to see the effects of blade lean on the development of secondary flows. It was found that a positive lean at the impeller exit shroud helps mitigate the wake region to contribute to more uniform flows, resulting in an increase of the impeller pressure and efficiency. A negative lean at the impeller exit causes a limited head rise due to a reduced blade loading on the shroud. A negative inlet lean at the shroud provided the worst performance.

Potential of variable diffuser vanes for extending the operating range of compressors and for improving the torque performance of turbocharged engines

2016 ◽  
Vol 231 (4) ◽  
pp. 555-566 ◽  
Author(s):  
Qiangqiang Huang ◽  
Xinqian Zheng
Keyword(s):  
High Pressure ◽  
Internal Combustion Engines ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Range Extension ◽  
Navier Stokes ◽  
Combustion Engines ◽  
Severe Problem ◽  
Operating Range ◽  
High Pressure Ratio

Turbocharging plays a significant role in internal-combustion engines. For engines in the future or for engines operating at a high altitude, compressors which are able to deliver a high pressure ratio are preferable. However, the poor low-end torque characteristics of turbocharged engines, which are often restricted by the narrow operating range of compressors at a high pressure ratio, result in a severe problem for turbocharging. The use of variable diffuser vanes is an effective method to increase the operating range, but the potential of an extended operating range at a high pressure ratio and improvement in the torque performance of engines is unclear. Nowadays, the pressure ratio of a turbocharger compressor may be only 1–4. Because of the increase in the pressure ratio, estimating the potential is ultimately worthwhile. In this paper the performances of a centrifugal compressor with different diffuser vane angles are investigated, the range extension and the improvement in the torque performance which benefited from variable diffuser vanes are estimated and the mechanisms for range extension are revealed. The approach includes steady three-dimensional Reynolds-averaged Navier–Stokes simulations and theoretical analysis. Adjusting the vane angle from −10° to 10° improves the operating range of a compressor from 23.5% (with fixed vanes) to 54.9% at a pressure ratio of 4.8. The range extension is obtained by utilizing the shifts in the choke line and the surge line. A method of assessing the choking component based on the simulation results is proposed. The diffuser, the flow stability of which was enhanced comparatively by closing it (pivoting the vanes by −10° and −5°), contributes mainly to reducing the surge flow. With this range extension, the improvement in the maximum torque is estimated to be 78%.

Effects of Reynolds number on the performance of a high pressure-ratio turbocharger compressor

2013 ◽  
Vol 56 (6) ◽  
pp. 1361-1369 ◽  
Author(s):  
XinQian Zheng ◽  
Yun Lin ◽  
BinLin Gan ◽  
WeiLin Zhuge ◽  
YangJun Zhang
Keyword(s):  
Reynolds Number ◽  
High Pressure ◽  
Pressure Ratio ◽  
High Pressure Ratio

Effect of Recirculation Device With Counter Swirl Vane on Performance of High Pressure Ratio Centrifugal Compressor

2011 ◽  
Author(s):  
Hideaki Tamaki
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Negative Slope ◽  
Tip Leakage Flow ◽  
Recirculation Flow ◽  
Operating Range ◽  
High Pressure Ratio

Centrifugal compressors used for turbochargers need to achieve a wide operating range. The author has developed a high pressure ratio centrifugal compressor with pressure ratio 5.7 for a marine use turbocharger. In order to enhance operating range, two different types of recirculation devices were applied. One is a conventional recirculation device. The other is a new one. The conventional recirculation device consists of an upstream slot, bleed slot and the annular cavity which connects both slots. The new recirculation device has vanes installed in the cavity. These vanes were designed to provide recirculation flow with negative preswirl at the impeller inlet, a swirl counterwise to the impeller rotational direction. The benefits of the application of both of the recirculation devices were ensured. The new device in particular, shifted surge line to a lower flow rate compared to the conventional device. This paper discusses how the new recirculation device affects the flow field in the above transonic centrifugal compressor by using steady 3-D calculations. Since the conventional recirculation device injects the flow with positive preswirl at the impeller inlet, the major difference between the conventional and new recirculation device is the direction of preswirl that the recirculation flow brings to the impeller inlet. This study focuses on two effects which preswirl of the recirculation flow will generate. (1) Additional work transfer from impeller to fluid. (2) Increase or decrease of relative Mach number. Negative preswirl increases work transfer from the impeller to fluid as the flow rate reduces. It increases negative slope on pressure ratio characteristics. Hence the recirculation flow with negative preswirl will contribute to stability of the compressor. Negative preswirl also increases the relative Mach number at the impeller inlet. It moves shock downstream compared to the conventional recirculation device. It leads to the suppression of the extension of blockage due to the interaction of shock with tip leakage flow.

Time-Averaged and Time-Accurate Aerodynamic Effects of Forward Rotor Cavity Purge Flow for a High-Pressure Turbine: Part I—Analytical and Experimental Comparisons

2012 ◽  
Author(s):  
Brian R. Green ◽  
Randall M. Mathison ◽  
Michael G. Dunn
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Film Cooling ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Flow Path ◽  
Field Analysis ◽  
High Pressure Turbine ◽  
Purge Flow

The effect of rotor purge flow on the unsteady aerodynamics of a high-pressure turbine stage operating at design corrected conditions has been investigated both experimentally and computationally. The experimental configuration consisted of a single-stage high-pressure turbine with a modern film-cooling configuration on the vane airfoil as well as the inner and outer end-wall surfaces. Purge flow was introduced into the cavity located between the high-pressure vane and the high-pressure disk. The high-pressure blades and the downstream low-pressure turbine nozzle row were not cooled. All hardware featured an aerodynamic design typical of a commercial high-pressure ratio turbine, and the flow path geometry was representative of the actual engine hardware. In addition to instrumentation in the main flow path, the stationary and rotating seals of the purge flow cavity were instrumented with high frequency response, flush-mounted pressure transducers and miniature thermocouples to measure flow field parameters above and below the angel wing. Predictions of the time-dependent flow field in the turbine flow path were obtained using FINE/Turbo, a three-dimensional, Reynolds-Averaged Navier-Stokes CFD code that had the capability to perform both steady and unsteady analysis. The steady and unsteady flow fields throughout the turbine were predicted using a three blade-row computational model that incorporated the purge flow cavity between the high-pressure vane and disk. The predictions were performed in an effort to mimic the design process with no adjustment of boundary conditions to better match the experimental data. The time-accurate predictions were generated using the harmonic method. Part I of this paper concentrates on the comparison of the time-averaged and time-accurate predictions with measurements in and around the purge flow cavity. The degree of agreement between the measured and predicted parameters is described in detail, providing confidence in the predictions for flow field analysis that will be provided in Part II.

scholarly journals The Design and Evaluation of a High Pressure Ratio Radial Turbine

1992 ◽  
Author(s):  
K. R. Pullen ◽  
N. C. Baines ◽  
S. H. Hill
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Pressure Ratio ◽  
Performance Measurements ◽  
Turbine Engine ◽  
High Pressure Ratio ◽  
Turbine Efficiency ◽  
Wide Range ◽  
Dimensional Parameters ◽  
Very High

A single stage, high speed, high pressure ratio radial inflow turbine was designed for a single shaft gas turbine engine in the 200 kW power range. A model turbine has been tested in a cold rig facility with correct simulation of the important non-dimensional parameters. Performance measurements over a wide range of operation were made, together with extensive volute and exhaust traverses, so that gas velocities and incidence and deviation angles could be deduced. The turbine efficiency was lower than expected at all but the lowest speed. The rotor incidence and exit swirl angles, as obtained from the rig test data, were very similar to the design assumptions. However, evidence was found of a region of separation in the nozzle vane passages, presumably caused by a very high curvature in the endwall just upstream of the vane leading edges. The effects of such a separation are shown to be consistent with the observed performance.

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