A Method for Predicting Compressor Cascade Total Pressure Losses When the Inlet Relative Mach Number Is Greater Than Unity

1971 ◽  
Vol 93 (1) ◽  
pp. 119-124 ◽  
Author(s):  
R. L. Balzer
Keyword(s):  
Total Pressure ◽  
Axial Flow ◽  
Shock Formation ◽  
Flow Conditions ◽  
Compressor Cascade ◽  
Viscous Effects ◽  
Pressure Losses ◽  
The Past ◽  
Flow Compressor ◽  
Made In

During the last few years, considerable progress has been made in predicting the total pressure losses from viscous effects for axial-flow compressor cascades. With the advent of the transonic and the supersonic stage, another pressure loss generating mechanism was introduced—the shock wave. Various methods have been published over the past few years accounting for the pressure losses associated with the shock formation, but of those reviewed by this author, none of them has been consistently successful for predicting the losses at other than design conditions. This paper develops a method which has given consistent success at all flow conditions for compressors with subsonic axial and supersonic relative velocities.

Effect of Incoming Wakes on the Stator Performance in a Single-Stage Low Speed Axial Flow Compressor Operating at Design and Near Stall Conditions

2016 ◽  
Author(s):  
Guillaume Pallot ◽  
Dai Kato ◽  
Wataru Kanameda ◽  
Yutaka Ohta
Keyword(s):  
Boundary Layers ◽  
Total Pressure ◽  
Axial Flow ◽  
Operating Conditions ◽  
Single Stage ◽  
Generation Process ◽  
Rotor Wake ◽  
Low Speed ◽  
Pressure Losses ◽  
Flow Compressor

Unsteady flow phenomena can significantly influence the performance of turbomachines. The convection of the wake coming from a rotor into a downstream stator is one of these phenomena. In the case of compressors, when the rotor wake is transported through a downstream stator, it undergoes viscous mixing and stretching (Smith 1966), which are two mechanisms responsible for its attenuation. The flow field of a low speed single-stage compressor comprising a rotor and a downstream stator is computed using unsteady CFD simulations at design and near stall conditions. Simulations results are compared to steady and unsteady data obtained from yawmeter and hotwire measurements at both rotor and stator exit. The study focuses on the rotor wake attenuation and the related unsteady total pressure loss generated in the stator passage. The loss due to viscous mixing of the rotor wake is calculated analytically using a wake dissipation model. Based on experimental, numerical and analytical results, a break-down of the unsteady total pressure losses is performed for the two operating conditions. Unsteady total pressure losses are classified into two categories. The first category is the loss generated by viscous mixing of the rotor wake and the second one the loss generated by the interactions between the rotor wake and the stator pressure and suction surfaces boundary layers (interaction loss). Results show that the interactions between the rotor wake and the stator surfaces boundary layers play an important part in the unsteady loss generation process and that the contribution of this interaction loss increases from design to near stall condition.

Non-Axisymmetric Endwall Contouring in a Compressor Cascade With Tip Gap

2014 ◽  
Author(s):  
Mahesh K. Varpe ◽  
A. M. Pradeep
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Three Dimensional ◽  
Axial Flow ◽  
Tip Clearance ◽  
Total Pressure Loss ◽  
Compressor Cascade ◽  
Flow Solver ◽  
Pressure Loss Coefficient ◽  
Flow Compressor

This paper describes the design of a non-axisymmetric hub contouring in a shroudless axial flow compressor cascade operating at near stall condition. Although, an optimum tip clearance reduces the total pressure loss, further minimization of the losses using hub contouring was achieved. The design methodology presented here combines an evolutionary principle with a three-dimensional CFD flow solver to generate different geometric profiles of the hub systematically. The total pressure loss coefficient was used as a single objective function to guide the search process for the optimum hub geometry. The resulting three dimensionally complex hub promises considerable benefits discussed in detail in this paper. A reduction of 15.2% and 16.23% in the total pressure loss and secondary kinetic energy, respectively, was achieved in the wake. The blade loading was observed to improve by about 4.53%. Other complementary benefits are also listed in the paper. The results confirm that non-axisymmetric contouring is an effective method for reducing the losses and thereby improving the performance of the cascade.

Benefits of Nonaxisymmetric Endwall Contouring in a Compressor Cascade With a Tip Clearance

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Mahesh K. Varpe ◽  
A. M. Pradeep
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Three Dimensional ◽  
Axial Flow ◽  
Vortex Generator ◽  
Tip Clearance ◽  
Total Pressure Loss ◽  
Compressor Cascade ◽  
Pressure Loss Coefficient ◽  
Flow Compressor

This paper describes the design of a nonaxisymmetric hub contouring in a shroudless axial flow compressor cascade operating at near stall condition. Although an optimum tip clearance (TC) reduces the total pressure loss, further reduction in the loss was achieved using hub contouring. The design methodology presented here combines an evolutionary principle with a three-dimensional (3D) computational fluid dynamics (CFD) flow solver to generate different geometric profiles of the hub systematically. The resulting configurations were preprocessed by GAMBIT© and subsequently analyzed computationally using ANSYSFluent©. The total pressure loss coefficient was used as a single objective function to guide the search process for the optimum hub geometry. The resulting three dimensionally complex hub promises considerable benefits discussed in detail in this paper. A reduction of 15.2% and 16.23% in the total pressure loss and secondary kinetic energy (SKE), respectively, is achieved in the wake region. An improvement of 4.53% in the blade loading is observed. Other complimentary benefits are also listed in the paper. The majority of the benefits are obtained away from the hub region. The contoured hub not only alters the pitchwise static pressure gradient but also acts as a vortex generator in an effort to alleviate the total pressure loss. The results confirm that nonaxisymmetric contouring is an effective method for reducing the losses and thereby improving the performance of the cascade.

scholarly journals Axial-flow compressor analysis under distorted phenomena at transonic flow conditions

2018 ◽  
Vol 5 (1) ◽  
pp. 1526458
Author(s):  
G Srinivas ◽  
K Raghunandana ◽  
Shenoy B Satish ◽  
Duc Pham
Keyword(s):  
Transonic Flow ◽  
Axial Flow ◽  
Flow Conditions ◽  
Axial Flow Compressor ◽  
Flow Compressor

The Effective Positions to Inject Water Into the Cascade of Compressor

2012 ◽  
Author(s):  
Jie Wang ◽  
Qun Zheng ◽  
Lanxin Sun ◽  
Mingcong Luo
Keyword(s):  
Kinetic Energy ◽  
Total Pressure ◽  
Lower Energy ◽  
Water Injection ◽  
Adverse Pressure Gradient ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Pressure Losses ◽  
Ansys Cfx ◽  
Highly Loaded

Generally, droplets are injected into air at inlet or interstage of a compressor. However, both cases did not consider how to utilize the kinetic energy of these moving droplets. Under the adverse pressure gradient of compressor, the lower energy fluids of blade surfaces and endwalls boundary layers would accumulate and separate. Kinetic droplets could accelerate the lower energy fluids and eliminate the separation. This paper mainly investigate the effective positions where to inject water and how to utilize the droplets’ kinetic energy. Four different injecting positions, which located on the suction surface and endwall, are chosen. The changes of vortexes in the compressor cascade are discussed carefully. In addition, the influences of water injection on temperature, total pressure losses and Mach number are analyzed. Numerical simulations are performed for a highly loaded compressor cascade with ANSYS CFX software.

scholarly journals Experimental Investigation of Rotor-Stator Interaction in Axial-Flow Turbines and Compressors

1998 ◽  
Vol 4 (4) ◽  
pp. 217-231
Author(s):  
Heinz E. Gallus
Keyword(s):  
Unsteady Flow ◽  
Total Pressure ◽  
Vector Fields ◽  
Guide Vane ◽  
Axial Flow ◽  
Tip Clearance ◽  
Inlet Guide Vane ◽  
Flow Measurements ◽  
Rotor Stator Interaction ◽  
Flow Compressor

Detailed results of unsteady flow measurements in a stator-rotor-stator assembly of an axial-flow turbine as well as an inlet guide vane-rotor-stator formation of an axial-flow compressor are presented in this paper.The measurements include the time-dependent 3-D velocity vector fields in the axial gaps between the blade rows by means of triple-hot wire-technique, furthermore the total pressure field downstream of the blade rows by means of semiconductor total pressure probes and the unsteady flow field determination in the rotor passages by LDV-technique. Special semiconductor pressure measurements along the casing all over the rotor tip clearance permit detailed discussion of the rotor tip clearance flows.The conclusion of the measured data provides a new and very instructive view of the physics of the unsteady blade-row interaction in axial-flow turbines and compressors.

An Axial Flow Compressor for Operation With Humid Air and Water Injection

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
Jesuino Takachi Tomita ◽  
Luciano Porto Bontempo ◽  
João Roberto Barbosa
Keyword(s):  
Computer Program ◽  
Water Injection ◽  
Axial Flow ◽  
Operating Conditions ◽  
Axial Position ◽  
Design Stage ◽  
Viscous Effects ◽  
Humid Air ◽  
Axial Flow Compressor ◽  
Flow Compressor

The first steps of the turbomachinery design usually rely on numerical tools based on inviscid formulation with corrections using loss models to account for viscous effects, secondary flows, tip clearances, and shock waves. The viscous effects are accounted for using semi-empirical correlations especially assembled for the chosen airfoils and range of operating conditions. Fast convergence and good accuracy are required from such design procedures. There are successful models that produce very accurate performance prediction. Among the methodologies commonly used, the streamline curvature (SLC) is used since those characteristics and the most important properties can be calculated reasonably well at any radial positions, assisting other more complex analysis programs. The SLC technique is, therefore, well suited for the design of axial flow compressors for reasons such as quick access to vital flow properties at the blade edges from which actions may be taken to improve its performance at the design stage. This work reports the association of a SLC computer program and commercial software for comparison purposes, as well as for grid generation required by a full 3D, turbulent Navier–Stokes computer program used for flow calculation in the blade passages. Application to a high performance three-stage axial flow compressor with inlet guide vane demonstrates the methodology adopted. The SLC program is also capable of calculating the compressor performance with humid air and water injection at any axial position along the compressor. The influence of water injection at different axial positions, water particle diameter, and temperature of water particles were studied for different humid air conditions. The positions of the evaporating water particles were calculated using their thermophysical and dynamic properties along the compressor.

Off-Design Transition and Separation Behavior of a CDA Cascade

1996 ◽  
Vol 118 (2) ◽  
pp. 204-210 ◽  
Author(s):  
W. Steinert ◽  
H. Starken
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Experimental Information ◽  
Complete Separation ◽  
Surface Boundary ◽  
Compressor Cascade ◽  
Adiabatic Wall ◽  
Design Data ◽  
Flow Compressor ◽  
Separation Behavior

The design of modern axial flow compressor blade sections as well as the code validation require experimental information about the transition and separation behavior of blade surface boundary layers. The experience has shown in the past that such information has to be obtained on the whole surface and not only by point measurements because both transition and separation may be of a three-dimensional nature even in a straight cascade. Therefore, a new visualization technique based on Liquid Crystals (LC), showing the adiabatic wall temperature, has been developed. With this method, transition, local separation, and complete separation can be detected. Design and off-design data of a subsonic (M1 = 0.62) Controlled Diffusion Airfoil (CDA) compressor cascade measured in a wind tunnel are presented. The LC results are supplemented by ink-injection tests and overall performance data.

scholarly journals CFD Analysis to Understand the Flow Behaviour of a Single Stage Transonic Axial Flow Compressor

2013 ◽  
Author(s):  
M. T. Shobhavathy ◽  
Premakara Hanoca
Keyword(s):  
Axial Flow ◽  
Flow Behaviour ◽  
Single Stage ◽  
Cfd Analysis ◽  
Flow Conditions ◽  
Blade Passage ◽  
Tip Leakage ◽  
Axial Flow Compressor ◽  
Design Speed ◽  
Flow Compressor

This paper comprises the Computational Fluid Dynamic (CFD) analysis to investigate the flow behaviour of a high speed single stage transonic axial flow compressor. Steady state analyses were carried out at design and part speed conditions to obtain the overall performance map using commercial CFD software ANSYS FLUENT. Radial distribution of flow parameters were obtained at 90% of design speed for the choked flow and near stall flow conditions. The predicted data were validated against available experimental results. The end wall flow fields were studied with the help of velocity vector plots and Mach number contours at peak efficiency and near stall flow conditions at 60% and 100% design speeds. This study exhibited the nature of a transonic compressor, having strong interaction between the rotor passage shock and the tip leakage vortex at design speed, which generates a region of high blockage in the rotor blade passage. The influence of this interaction extends around15% of the blade outer span at design speed and in the absence of blade passage shock at 60% design speed, the influence of tip leakage flow observed was around 8%.

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