The Influence of Shrouded Stator Cavity Flows on the Aerodynamic Performance of a High-Speed Multistage Axial-Flow Compressor

Author(s):  
Dai Kato ◽  
Mai Yamagami ◽  
Naoki Tsuchiya ◽  
Hidekazu Kodama

This paper investigates numerically the effects of shrouded stator seal cavity flows on a high-speed, six-stage, advanced axial-flow compressor performance. Two cases of fully three-dimensional unsteady Reynolds-averaged Navier-Stokes simulations are performed. The first case includes only the main flow path without cavities, while the second case takes into account the effect of cavities by fully meshing and solving the seal cavity flows under each of the stator vanes. Both simulations included rotor blade tip clearances. The latter case showed 1.7 point degradation in efficiency from the first case. Contributors to the overall performance degradation, such as windage heating, mixing loss due to seal leakage flow with the main flow, and additional loss of the rotors and stators due to alteration in velocity triangles, are identified by comparing the two simulation results. Compared to theoretical or semi-empirical leakage and windage models, higher loss production and temperature rise are found especially in mid to rear stages. Unsteady effects for such differences are discussed.

Author(s):  
A. Gill ◽  
T. W. von Backström ◽  
T. M. Harms

This article describes an experimental investigation of the flow structures occurring in an axial flow compressor during second quadrant operation for reversed rotor rotation in the incompressible flow regime. In second quadrant operation, the flow direction is reversed, but the pressure is lower at the compressor inlet than at the outlet. The compressor thus acts as an axial flow turbine. A three stage axial flow compressor, with a mass flow rate of 2.7 kg/s and a pressure ratio of 1.022 was investigated. The design rotor tip Mach number is 0.2. Three operational points within the second quadrant were investigated, at flow coefficients of −0.482, −0.553 and −0.843. A five hole conical probe and a 50 micron diameter inclined hot film anemometer were used in this investigation. Radial traverses downstream of rotor rows and a time-dependent area traverse downstream of the first stage stator were performed. Three-dimensional time-dependent numerical Navier-Stokes solutions using the non-linear harmonic approximation for single blade passages in each blade row for each of the cases are compared with experimental work. The compressor has already been show to be capable of attaining relatively high turbine efficiency (76%) when operating in this mode. Examination of the flow field shows that little to no flow separation occurs on the rotor or stator blades. The wakes of all blades are found to be thin and sharp, and the area between wakes is large and approximately uniform. Numerical results agree relatively well with experimental results.


Author(s):  
Dario Bruna ◽  
Carlo Cravero ◽  
Mark G. Turner

The development of a computational tool (MP-LOS) for the aerodynamic loss modeling and prediction for axial-flow compressor blade sections is presented in this paper. A state-of-the-art quasi 3-D flow solver, MISES, has been used for the flow analysis on existing airfoil geometries in many working conditions. Different values of inlet flow angle, inlet Mach number, AVDR, Reynolds number and solidity have been chosen to investigate a possible working range. The target is a loss prediction formulation that will be introduced into throughflow or axisymmetric Navier-Stokes codes for the performance prediction of multistage axial flow compressors. The loss coefficient has been correlated to the flow parameters that have shown an influence on the profile loss for the blades under study. The proposed correlation, using the described computational approach, can be extended to any profile family with the aid of any code for the parametric design of blade profiles.


Author(s):  
Tian Liang ◽  
Bo Liu ◽  
Stephen Spence ◽  
Liying Jiao

To extend the current understanding of the circumferential groove casing suction applied to a counter-rotating axial flow compressor, the impact of different axial locations of the circumferential suction groove on the characteristics of the tip leakage flow (TLF) and the corresponding physical mechanisms producing the stability enhancement have been studied based on validated numerical simulations. The results show that the optimal location for the suction groove is at around 20% axial chord, which demonstrated a high potential for reducing additional stall mass flow coefficient with about 8.4% increment in the stall margin. After the casing suction groove was applied, the interface between the incoming main flow and TLF was pushed significantly downstream in the second rotor. The blade loading in the region below the groove, the tip leakage flow angle and the reversed axial momentum flux injected into main flow passage through the tip gap were all reduced, which contributed to the stall margin improvement. Detailed analysis of the tip leakage flow structures showed that the TLF originating from different chord locations played different roles in the stall inception process. It was found to be more effective to improve stall margin and adiabatic efficiency by controlling the front part of the TLF, which was most sensitive.


1990 ◽  
Author(s):  
STEVEN GORRELL ◽  
WILLIAM COPENHAVER ◽  
WALTER O'BRIEN

1992 ◽  
Vol 114 (3) ◽  
pp. 675-685 ◽  
Author(s):  
A. Goto

The effect of difference in rotor tip clearance on the mean flow fields and unsteadiness and mixing across a stator blade row were investigated using hot-wire anemometry, pressure probes, flow visualization, and the ethylene tracer-gas technique on a single-stage axial flow compressor. The structure of the three-dimensional flow fields was discussed based on results of experiments using the 12-orientation single slanted hotwire technique and spectrum analysis of velocity fluctuation. High-pass filtered measurements of turbulence were also carried out in order to confirm small-scale velocity fluctuation, which is more realistically referred to as turbulence. The span-wise distribution of ethylene gas spreading, estimated by the measured small-scale velocity fluctuation at the rotor exit, agreed quite well with that which was experimentally measured. This fact suggests the significant role of turbulence, generated within the rotor, in the mixing process across the downstream stator. The value of the maximum mixing coefficient in the tip region was found to increase linearly as the tip clearance became enlarged, starting from the value at midspan.


Energies ◽  
2016 ◽  
Vol 9 (4) ◽  
pp. 296 ◽  
Author(s):  
Tao Ning ◽  
Chun-Wei Gu ◽  
Wei-Dou Ni ◽  
Xiao-Tang Li ◽  
Tai-Qiu Liu

2018 ◽  
Vol 78 ◽  
pp. 271-279 ◽  
Author(s):  
Mauro Righi ◽  
Vassilios Pachidis ◽  
László Könözsy ◽  
Lucas Pawsey

Author(s):  
Pritam Batabyal ◽  
Dilipkumar B. Alone ◽  
S. K. Maharana

This paper presents a numerical case study of various stepped tip clearances and their effect on the performance of a single stage transonic axial flow compressor, using commercially available software ANSYS FLUENT 14.0. A steady state, implicit, three dimensional, pressure based flow solver with SST k-Ω turbulence model has been selected for the numerical study. The stepped tip clearances have been compared with the baseline model of zero tip clearance at 70% and 100 % design speed. It has been observed that the compressor peak stage efficiency and maximum stage pressure ratio decreases as the tip clearances in the rear part are increased. The stall margin also increases with increase in tip clearance compared to the baseline model. An ‘optimum’ value of stepped tip clearance has been obtained giving peak stage compressor performance. The CFD results have been validated with the earlier published experimental data on the same compressor at 70% design speed.


Author(s):  
Richard A. Mulac ◽  
John J. Adamczyk

The advancement of high-speed axial flow multistage compressors is impeded by a lack of detailed flow field information. Recent developments in compressor flow modeling and numerical simulation have the potential to provide needed information in a timely manner. This paper, which consists of two parts, will explore this topic. The first part will address the development of a computer program to solve the viscous form of the average-passage equation system for multistage turbomachinery. Programming issues such as in-core versus out-of-core data storage and CPU utilization (parallelization, vectorization, and chaining) will be addressed. Code performance will be evaluated through the simulation of the first four stages of a five stage, high-speed, axial flow compressor on a CRAY Y-MP8/8128 computer. The second part will address the flow physics which can be obtained from the numerical simulation. In particular, an examination of the endwall flow structure will be made, and its impact on blockage distribution assessed.


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