Predictions of the Flow in Repeating Stages of Axial Compressors Using Navier-Stokes Solvers

1995 ◽  
Author(s):  
John J. Bolger ◽  
John H. Horlock
Keyword(s):  
Flow Analysis ◽  
Axial Flow ◽  
Navier Stokes ◽  
Good Prediction ◽  
Viscous Effects ◽  
Flow Angle ◽  
Axial Compressors ◽  
Multi Stage ◽  
Flow Compressor ◽  
Comparison With Experimental Data

In a well designed multi-stage axial flow compressor the flow quickly settles down to a repeating condition in which the flow angle and axial velocity profiles do not deteriorate further; they are more or less unchanged between entry to and exit from a deeply embedded stage. In early work, the flow in such repeating stages was studied using inviscid secondary flow analysis, coupled with empirical data on clearance flows, and also by inviscid numerical calculation. Underturning near the annulus walls was generally predicted but this was not convincingly confirmed by comparison with experimental data for repeating stage flows; it was apparent that viscous effects were important and should be taken into account. Further investigation of the flow in repeating stages has therefore been undertaken using Navier-Stokes solvers for comparison with early experimental results and improved test data more recently available. It is established that, with care, quite a good prediction of repeating stage flows can be made using steady-flow 3D viscous methods, and more general conclusions of greater validity can be drawn about over- or underturning at the annulus walls than the universal underturning predicted in the earlier inviscid approaches for moderately loaded stages.

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.

The Measurement and Interpretation of Flow within Rotating Stall Cells in Axial Compressors

1978 ◽  
Vol 20 (2) ◽  
pp. 101-114 ◽  
Author(s):  
I. J. Day ◽  
N.A. Cumpsty
Keyword(s):  
Flow Direction ◽  
Axial Flow ◽  
Tangential Direction ◽  
Rotating Stall ◽  
Design Flow ◽  
Flow Measurements ◽  
Axial Compressors ◽  
Multi Stage ◽  
Wide Range ◽  
Flow Compressor

Detailed flow measurements obtained by a new measuring technique are presented for the flow in a stalled axial-flow compressor. Results were obtained from a wide range of compressor builds, including multi-stage and single-stage configurations of various design flow rates and degrees of reaction. Instantaneous recordings of absolute velocity, flow direction and total and static pressures have been included for both full-span and part-span stall. With the aid of these results, it has been shown that the conventional model of the flow in a stall cell is erroneous. An alternative model is proposed, based on the observation that the fluid must cross from one side of the cell to the other in order to preserve continuity in the tangential direction. An investigation of the experimental results also reveals the finer details of the flow in the cell and shows how these details are related to the design flow rate of the compressor. The influence of these cell details on the power absorbed by a stalled compressor are investigated, and consideration is given to the complex pressure patterns encountered in the compressor.

A Numerical Investigation of Loss Coefficient Variation in Various Incidence Angles in Tandem Blades Cascade

2014 ◽  
Author(s):  
Arash Soltani Dehkharqani ◽  
Masoud Boroomand ◽  
Hamzeh Eshraghi
Keyword(s):  
Pressure Ratio ◽  
Axial Flow ◽  
Suction Side ◽  
Loss Coefficient ◽  
Flow Coefficient ◽  
Flow Angle ◽  
Multi Stage ◽  
Wide Range ◽  
And Performance ◽  
Flow Compressor

There is a severe tendency to reduce weight and increase power of gas turbine. Such a requirement is fulfilled by higher pressure ratio of compressor stages. Employing tandem blades in multi-stage axial flow compressors is a promising methodology to control separation on suction sides of blades and simultaneously implement higher turning angle to achieve higher pressure ratio. The present study takes into account the high flow deflection capabilities of the tandem blades consisting of NACA-65 airfoil with fixed percent pitch and axial overlap at various flow incidence angles. In this regard, a two-dimensional cascade model of tandem blades is constructed in a numerical environment. The inlet flow angle is varied in a wide range and overall loss coefficient and deviation angles are computed. Moreover, the flow phenomena between the blades and performance of both forward and afterward blades are investigated. At the end, the aerodynamic flow coefficient of tandem blades are also computed with equivalent single blades to evaluate the performance of such blades in both design and off-design domain of operations. The results show that tandem blades are quite capable of providing higher deflection with lower loss in a wide range of operation and the base profile can be successfully used in design of axial flow compressor. In comparison to equivalent single blades, tandem blades have less dissipation because the momentum exerted on suction side of tandem blades confines the size of separation zone near trailing edges of blades.

Secondary Flow in Repeating Stages of Axial Turbomachines

1995 ◽  
Vol 209 (2) ◽  
pp. 101-110 ◽  
Author(s):  
J H Horlock
Keyword(s):  
Experimental Data ◽  
Secondary Flow ◽  
Flow Analysis ◽  
Axial Flow ◽  
Streamwise Vorticity ◽  
Flow Phenomenon ◽  
Multi Stage ◽  
Axial Velocity Profile ◽  
Flow Through ◽  
Flow Compressor

In a well-designed multi-stage axial flow compressor, the flow settles down to a repeating condition, in which the axial velocity profile does not deteriorate further; it is more or less unchanged between the entry and the exit of a deeply embedded stage. However, experimental data also show that the flow angles repeat, and it is this flow phenomenon that is discussed in the paper. Secondary flow analysis, coupled with empirical data on clearance flows, is used to give a description of the flow in such a repeating stage. The secondary flow at exit from a row involves both the streamwise vorticity generated in that row and the vorticity that exists at entry—the so-called ‘skew’ vorticity due to a non-uniform velocity from a stator being received by a moving rotor (and a similar effect from the rotor to the stator). However, clearance vorticity—shed from the rotor tip (casing) section and the stator root (hub) section—is also present and can be taken into account. Calculations made using the analyses are compared with some limited experimental data drawn from the published literature. Predicted underturning at rotor tip (casing) sections is confirmed by experiments; similarly, predicted underturning at stator tip (casing) sections accords with observations in one compressor but not in another. However, no universal conclusion (on whether underturning or overturning usually occurs) can be drawn for the flow through the rotor and stator root (hub) sections, as either entry or generated secondary vorticity may dominate.

scholarly journals 3-D Viscous Flow Analysis of an Axial Flow Pump Impeller

1997 ◽  
Vol 3 (3) ◽  
pp. 153-161 ◽  
Author(s):  
Steven M. Miner
Keyword(s):  
Stokes Equations ◽  
Flow Analysis ◽  
Axial Flow ◽  
Flow Coefficient ◽  
Navier Stokes ◽  
Design Parameters ◽  
Pump Impeller ◽  
Flow Angle ◽  
Axial Flow Pump ◽  
Flow Pump

A commercial CFD code is used to compute the flow field within the first stage impeller of a two stage axial flow pump. The code solves the 3-D Reynolds Averaged Navier Stokes equations in a rotating cylindrical coordinate system using a standardk−εturbulence model. Stage design parameters are, rotational speed 870 rpm, flow coefficientφ=0.12, head coefficientψ=0.06, and specific speed 2.86 (8070 US). Results from the study include relative and absolute velocities, flow angles, and static and total pressures. Comparison is made to measured data available for the same impeller at two planes, one upstream of the impeller and the other downstream. The comparisons are for circumferentially averaged results and include axial and tangential velocities, impeller exit flow angle, static pressure, and total pressure. Results of this study show that the computational results closely match the shapes and magnitudes of the measured profiles, indicating that CFD can be used to accurately predict performance.

An Improved Axial Flow Compressor Design

1965 ◽  
Vol 69 (659) ◽  
pp. 791-793 ◽  
Author(s):  
M. D. C. Doyle
Keyword(s):  
Mach Number ◽  
Axial Flow ◽  
Gas Temperature ◽  
Efficient Operation ◽  
Axial Compressors ◽  
Multi Stage ◽  
Wide Range ◽  
Design Speed ◽  
High Mach ◽  
Flow Compressor

In using the method of stage stacking to compute the off-design performance of multi-stage axial compressors, it has been observed that the limitation on performance at speeds above the design speed has been set by the stall and the choke points of the rear stages(1). Thus if the rear stages can absorb a wide range of mass flows between stalled conditions and choked conditions, a better performance could be obtained.Compressor stages using low stagger blades will absorb a large range of mass flow between stalled and choked condition; but because of the high axial velocity involved in their use, they tend to be unsuitable for low pressure stages because of the high Mach number obtained. In the higher pressure stages the increased gas temperature will lower the Mach number for the same velocity and give more efficient operation.

scholarly journals Monitoring of Aerodynamic Load and Detection of Stall in Multi Stage Axial Compressors

1993 ◽  
Author(s):  
H. Hönen ◽  
H. E. Gallus
Keyword(s):  
Axial Flow ◽  
Operating Conditions ◽  
Normal Operation ◽  
Aerodynamic Load ◽  
Frequency Spectra ◽  
Axial Compressors ◽  
Multi Stage ◽  
Flow Compressor ◽  
The Stability ◽  
Hot Film

The unsteady flow in a single stage axial flow compressor at different operating conditions has been investigated with hot wire and hot film probes to find out the influence of the aerodynamic compressor load onto the periodic fluctuations. These results are compared with measurements in the last stages of a multi stage high pressure compressor of a gas turbine for normal operation and under stall conditions. From the patterns of the frequency spectra of the measuring signals a parameter for the detection of the approach to the stability line of a compressor is derived. A method for the on line monitoring of the aerodynamic load is presented. Based on these results a monitoring system has been developed. First experiences with this system, applied to two multi stage compressors are reported.

Three-Dimensional Flows and Loss Reduction in Axial Compressors

1987 ◽  
Vol 109 (3) ◽  
pp. 354-361 ◽  
Author(s):  
Y. Dong ◽  
S. J. Gallimore ◽  
H. P. Hodson
Keyword(s):  
Three Dimensional ◽  
Axial Compressor ◽  
Axial Flow ◽  
Tracer Gas ◽  
Suction Surface ◽  
Axial Compressors ◽  
Small Clearance ◽  
Oil Flow ◽  
Stator Blade ◽  
Flow Compressor

Measurements have been performed in a low-speed high-reaction single-stage axial compressor. Data obtained within and downstream of the rotor, when correlated with the results of other investigations, provide a link between the existence of suction surface–hub corner separations, their associated loss mechanisms, and blade loading. Within the stator, it has been shown that introducing a small clearance between the stator blade and the stationary hub increases the efficiency of the stator compared to the case with no clearance. Oil flow visualizaton indicated that the leakage reduced the extensive suction surface–hub corner separation that would otherwise exist. A tracer gas experiment showed that the large radial shifts of the surface streamlines indicated by the oil flow technique were only present close to the blade. The investigation demonstrates the possible advantages of including hub clearance in axial flow compressor stator blade rows.

scholarly journals Effect of Circumferential Single Casing Groove Location on the Flow Stability under Tip-Clearance Effect in a Transonic Axial Flow Compressor Rotor

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6143
Author(s):  
Xiaoxiong Wu ◽  
Bo Liu ◽  
Botao Zhang ◽  
Xiaochen Mao
Keyword(s):  
Control Mechanism ◽  
Incidence Angle ◽  
Axial Flow ◽  
Flow Stability ◽  
Tip Clearance ◽  
Tip Leakage Flow ◽  
Flow Angle ◽  
Axial Flow Compressor ◽  
Compressor Rotor ◽  
Flow Compressor

Numerical simulations have been performed to study the effect of the circumferential single-grooved casing treatment (CT) at multiple locations on the tip-flow stability and the corresponding control mechanism at three tip-clearance-size (TCS) schemes in a transonic axial flow compressor rotor. The results show that the CT is more efficient when its groove is located from 10% to 40% tip axial chord, and G2 (located at near 20% tip axial chord) is the best CT scheme in terms of stall-margin improvement for the three TCS schemes. For effective CTs, the tip-leakage-flow (TLF) intensity, entropy generation and tip-flow blockage are reduced, which makes the interface between TLF and mainstream move downstream. A quantitative analysis of the relative inlet flow angle indicates that the reduction of flow incidence angle is not necessary to improve the flow stability for this transonic rotor. The control mechanism may be different for different TCS schemes due to the distinction of the stall inception process. For a better application of CT, the blade tip profile should be further modified by using an optimization method to adjust the shock position and strength during the design of a more efficient CT.

Aerodynamic Design Optimization of an Axial Flow Compressor Rotor

2002 ◽  
Author(s):  
Chan-Sol Ahn ◽  
Kwang-Yong Kim
Keyword(s):  
Design Optimization ◽  
Response Surface ◽  
Computing Time ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Axial Flow ◽  
Navier Stokes ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Design Variables

Design optimization of a transonic compressor rotor (NASA rotor 37) using the response surface method and three-dimensional Navier-Stokes analysis has been carried out in this work. The Baldwin-Lomax turbulence model was used in the flow analysis. Three design variables were selected to optimize the stacking line of the blade. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, adiabatic efficiency was successfully improved. It was found that the optimization process provides reliable design of a turbomachinery blade with reasonable computing time.

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