Reverse Flow Turbine-Like Operation of an Axial Flow Compressor

2012 ◽  
Author(s):  
A. Gill ◽  
T. W. von Backström ◽  
T. M. Harms
Keyword(s):  
Reverse Flow ◽  
Flow Direction ◽  
Pressure Ratio ◽  
Harmonic Approximation ◽  
Three Dimensional ◽  
Axial Flow ◽  
Time Dependent ◽  
Navier Stokes ◽  
Axial Flow Compressor ◽  
Flow Compressor

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.

The Flow Field Within an Axial Flow Compressor at Extremely High Flow Coefficients

2010 ◽  
Author(s):  
A. Gill ◽  
T. W. von Backstro¨m ◽  
T. M. Harms
Keyword(s):  
Steady State ◽  
Pressure Ratio ◽  
Harmonic Approximation ◽  
Axial Flow ◽  
Pressure Rise ◽  
Flow Coefficient ◽  
Time Dependent ◽  
Fourth Quadrant ◽  
Axial Flow Compressor ◽  
Flow Compressor

This article describes an experimental investigation of the flow structures occurring in a three-stage axial flow compressor during fourth quadrant operation in the incompressible flow regime. In fourth quadrant operation, the flow coefficient exceeds the design value to such a degree that the pressure difference between the compressor inlet and outlet becomes negative, and the compressor acts as a badly designed turbine. The pressure rise characteristic curve thus extends into the fourth quadrant of the compressor map. 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 fourth quadrant were investigated, at flow coefficients of 0.665, 0.747 and 1.024. A five hole conical probe and a 50 μm 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 steady-state and time-dependent numerical Navier-Stokes solutions for single blade passages in each blade row for each of the cases are compared with experimental work. Large wakes were observed downstream of all stator rows, as a result of significant flow separation on stator blades. The area fraction of the flow passage affected by the wakes increases as the flow coefficient increases. Flow through rotor blade-passages is heavily affected by the blade position relative to upstream stator wakes. Due to the effect of the stator wakes on downstream blading, time-dependent solutions using the nonlinear harmonic approximation were found to agree better with experimental results than steady-state solutions using mixing planes between blade rows.

Numerical Studies on Effect of Stepped Tip Clearance Height on the Performance of Single Stage Transonic Axial Flow Compressor

2013 ◽  
Author(s):  
Pritam Batabyal ◽  
Dilipkumar B. Alone ◽  
S. K. Maharana
Keyword(s):  
Numerical Study ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Flow ◽  
Single Stage ◽  
Tip Clearance ◽  
Baseline Model ◽  
Axial Flow Compressor ◽  
Design Speed ◽  
Flow Compressor

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.

Flow Fields in an Axial Flow Compressor During Four-Quadrant Operation

2013 ◽  
Author(s):  
Andrew Gill ◽  
Theodor W. von Backström ◽  
Thomas M. Harms ◽  
Dwain Dunn
Keyword(s):  
Flow Direction ◽  
Tangential Velocity ◽  
Axial Compressor ◽  
Axial Flow ◽  
Pressure Rise ◽  
Flow Fields ◽  
Time Dependent ◽  
Axial Flow Compressor ◽  
Compressor Rotor ◽  
Flow Compressor

It has been shown in previous investigations that when all combinations of both positive and negative direction of rotation and flow direction are allowed in operating a multistage axial flow compressor, the operating point may be in any of the four quadrants of the pressure rise versus flow characteristic. The present paper is the first discussion of the flow field of all possible modes of operation of an axial flow compressor. During the present study interstage time dependent hot film velocity measurements and five hole pneumatic probe measurements were combined with steady and time dependent CFD solutions to investigate the flow fields in the three-stage axial compressor. Results are presented in terms of mean-line velocity triangles, mean stream surface plots, mid-span radial velocity contours right through the compressor, rotor-downstream radial distributions of axial and tangential velocity, stator-downstream axial velocity contours and mid-span entropy contours through the compressor. Main flow features are pointed out and discussed. The study was instigated in an effort to understand possible accident scenarios in a three-shaft closed cycle nuclear powered helium gas turbine.

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

2011 ◽  
Author(s):  
Dai Kato ◽  
Mai Yamagami ◽  
Naoki Tsuchiya ◽  
Hidekazu Kodama
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Axial Flow ◽  
Main Flow ◽  
Navier Stokes ◽  
Cavity Flows ◽  
Axial Flow Compressor ◽  
First Case ◽  
Flow Compressor ◽  
Unsteady Effects

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.

Flow Fields in an Axial Flow Compressor During Four-Quadrant Operation

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Andrew Gill ◽  
Theodor W. Von Backström ◽  
Thomas M. Harms
Keyword(s):  
Flow Direction ◽  
Tangential Velocity ◽  
Axial Compressor ◽  
Axial Flow ◽  
Pressure Rise ◽  
Flow Fields ◽  
Time Dependent ◽  
Axial Flow Compressor ◽  
Compressor Rotor ◽  
Flow Compressor

It has been shown in previous investigations that when all combinations of both positive and negative direction of rotation and flow direction are allowed in operating a multistage axial flow compressor, the operating point may be in any of the four quadrants of the pressure rise versus flow characteristic. The present paper is the first discussion of the flow field of all possible modes of operation of an axial flow compressor. During the present study interstage time dependent hot film velocity measurements and five hole pneumatic probe measurements were combined with steady and time dependent CFD solutions to investigate the flow fields in the three-stage axial compressor. Results are presented in terms of mean-line velocity triangles, mean stream surface plots, midspan radial velocity contours right through the compressor, rotor-downstream radial distributions of axial and tangential velocity, stator-downstream axial velocity contours and midspan entropy contours through the compressor. Main flow features are pointed out and discussed. The study was instigated in an effort to understand possible accident scenarios in a three-shaft closed cycle nuclear powered helium gas turbine.

The Development of an Aerodynamic Performance Prediction Tool for Modern Axial Flow Compressor Profiles

2006 ◽  
Author(s):  
Dario Bruna ◽  
Carlo Cravero ◽  
Mark G. Turner
Keyword(s):  
Performance Prediction ◽  
Parametric Design ◽  
Flow Analysis ◽  
Axial Flow ◽  
Navier Stokes ◽  
Flow Angle ◽  
Flow Solver ◽  
Aerodynamic Loss ◽  
Axial Flow Compressor ◽  
Flow Compressor

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.

Three-Dimensional Flow and Mixing in an Axial Flow Compressor With Different Rotor Tip Clearances

1992 ◽  
Vol 114 (3) ◽  
pp. 675-685 ◽  
Author(s):  
A. Goto
Keyword(s):  
Velocity Fluctuation ◽  
Three Dimensional ◽  
Axial Flow ◽  
Flow Fields ◽  
Tip Clearance ◽  
Small Scale ◽  
Three Dimensional Flow ◽  
Axial Flow Compressor ◽  
Dimensional Flow ◽  
Flow Compressor

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.

Numerical Simulation of Steady Air Injection Flow Control Effects on a Transonic Axial Flow Compressor

2012 ◽  
Vol 224 ◽  
pp. 352-357
Author(s):  
Islem Benhegouga ◽  
Ce Yang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Leading Edge ◽  
Air Injection ◽  
Axial Flow Compressor ◽  
Blade Tip ◽  
Flow Compressor

In this work, steady air injection upstream of the blade leading edge was used in a transonic axial flow compressor, NASA rotor 37. The injectors were placed at 27 % upstream of the axial chord length at blade tip, the injection mass flow rate is 3% of the chock mass flow rate, and 3 yaw angles were used, respectively -20°, -30°, and -40°. Negative yaw angles were measured relative to the compressor face in opposite direction of rotational speeds. To reveal the mechanism, steady numerical simulations were performed using FINE/TURBO software package. The results show that the stall mass flow can be decreased about 2.5 %, and an increase in the total pressure ratio up to 0.5%.

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