Modelling the Axial-Flow Compressors for Calculating Starting of Turbojet Engines

1985 ◽  
Author(s):  
Yan De-You
Keyword(s):  
Excellent Agreement ◽  
Axial Flow ◽  
Structural Formula ◽  
Experimental Results ◽  
Low Speed ◽  
Structural Formulae ◽  
Axial Flow Compressors

This paper provides a method of modelling the axial-flow compressors in the low speed starting regime of an engine from windmilling to idling. A structural formula for the model is established by means of reference (1). A method of step-by-step regression is provided by the author for determining the coefficient matrices of the structural formulae. Excellent agreement was obtained between the computational and experimental results.

Mixing in Axial Flow Compressors: Part I — Test Facilities and Measurements in a Four-Stage Compressor

1990 ◽  
Author(s):  
Y. S. Li ◽  
N. A. Cumpsty
Keyword(s):  
Axial Flow ◽  
Single Stage ◽  
Two Dimensional ◽  
Similar Magnitude ◽  
Low Speed ◽  
The Third ◽  
Mixing Coefficients ◽  
Experimental Facilities ◽  
Axial Flow Compressors

The mechanism of mixing in axial flow compressors has been investigated in two low speed machines. For reasons of length this is described in two parts. Results in a 4-stage compressor are described here in Part I and show that the mixing coefficients across the first and the third stators are of similar magnitude. Part I also describes the background and experimental facilities and techniques used in both parts together with the nomenclature and all the references. Part II describes the results from a large single stage compressor. It also presents measurements of mixing in a simple two-dimensional duct, and presents conclusions for the whole investigation.

Mixing in Axial Flow Compressors: Part I—Test Facilities and Measurements in a Four-Stage Compressor

1991 ◽  
Vol 113 (2) ◽  
pp. 161-165 ◽  
Author(s):  
Y. S. Li ◽  
N. A. Cumpsty
Keyword(s):  
Axial Flow ◽  
Single Stage ◽  
Two Dimensional ◽  
Similar Magnitude ◽  
Low Speed ◽  
The Third ◽  
Mixing Coefficients ◽  
Experimental Facilities ◽  
Axial Flow Compressors

The mechanism of mixing in axial flow compressors has been investigated in two low-speed machines. For reasons of length this is described in two parts. Results in a four-stage compressor are described here in Part I and show that the mixing coefficients across the first and the third stators are of similar magnitude. Part I also describes the background and experimental facilities and techniques used in both parts together with the nomenclature and all the references. Part II describes the results from a large single-stage compressor. It also presents measurements of mixing in a simple two-dimensional duct, and presents conclusions for the whole investigation.

Stall Margin Improvement by Casing Treatment—Its Mechanism and Effectiveness

1977 ◽  
Vol 99 (1) ◽  
pp. 121-133 ◽  
Author(s):  
H. Takata ◽  
Y. Tsukuda
Keyword(s):  
Axial Flow ◽  
Stall Margin ◽  
Low Speed ◽  
Casing Treatment ◽  
Blade Row ◽  
Stall Margin Improvement ◽  
Flow Through ◽  
Compressor Performance ◽  
Axial Flow Compressors

Experiments on the effect of casing treatment were carried out using low-speed axial-flow compressors. Results on the overall compressor performance and on the flow through the blade row as well as the flow within the treatment slots are presented. Then, based on the experiments, a possible mechanism of the stall margin improvement is suggested.

Loss Reduction in Axial-Flow Compressors Through Low-Speed Model Testing

1985 ◽  
Vol 107 (2) ◽  
pp. 354-363 ◽  
Author(s):  
D. C. Wisler
Keyword(s):  
Flow Separation ◽  
High Speed ◽  
Three Dimensional ◽  
Axial Flow ◽  
Secondary Flows ◽  
Stall Margin ◽  
Low Speed ◽  
High Loss ◽  
Aerodynamic Model ◽  
Axial Flow Compressors

A systematic procedure for reducing losses in axial-flow compressors is presented. In this procedure, a large, low-speed, aerodynamic model of a high-speed core compressor is designed and fabricated based on aerodynamic similarity principles. This model is then tested at low speed where high-loss regions associated with three-dimensional endwall boundary layers, flow separation, leakage, and secondary flows can be located, detailed measurements made, and loss mechanisms determined with much greater accuracy and much lower cost and risk than is possible in small, high-speed compressors. Design modifications are made by using custom-tailored airfoils and vector diagrams, airfoil endbends, and modified wall geometries in the high-loss regions. The design improvements resulting in reduced loss or increased stall margin are then scaled to high speed. This paper describes the procedure and presents experimental results to show that in some cases endwall loss has been reduced by as much as 10 percent, flow separation has been reduced or eliminated, and stall margin has been substantially improved by using these techniques.

Convective Losses From Cavity Solar Receivers—Comparisons Between Analytical Predictions and Experimental Results

1983 ◽  
Vol 105 (1) ◽  
pp. 29-33 ◽  
Author(s):  
A. M. Clausing
Keyword(s):  
Experimental Data ◽  
Experimental Evidence ◽  
Analytical Model ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Refined Model ◽  
Wall Area

Cavity solar receivers are generally believed to have higher thermal efficiencies than external receivers due to reduced losses. A simple analytical model was presented by the author which indicated that the ability to heat the air inside the cavity often controls the convective loss from cavity receivers. Thus, if the receiver contains a large amount of inactive hot wall area, it can experience a large convective loss. Excellent experimental data from a variety of cavity configurations and orientations have recently become available. These data provided a means of testing and refining the analytical model. In this manuscript, a brief description of the refined model is presented. Emphasis is placed on using available experimental evidence to substantiate the hypothesized mechanisms and assumptions. Detailed comparisons are given between analytical predictions and experimental results. Excellent agreement is obtained, and the important mechanisms are more clearly delineated.

Validating Numerical CFD Simulations With Experimental Data for Turbulence Phenomena in Axial Flow Gas Turbine Diffusers

2009 ◽  
Author(s):  
Farrokh Zarifi-Rad ◽  
Hamid Vajihollahi ◽  
James O’Brien
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Axial Flow ◽  
Experimental Results ◽  
Scale Model ◽  
Data Set ◽  
Pressure Profiles ◽  
Scale Models ◽  
Inlet Conditions

Scale models give engineers an excellent understanding of the aerodynamic behavior behind their design; nevertheless, scale models are time consuming and expensive. Therefore computer simulations such as Computational Fluid Dynamics (CFD) are an excellent alternative to scale models. One must ask the question, how close are the CFD results to the actual fluid behavior of the scale model? In order to answer this question the engineering team investigated the performance of a large industrial Gas Turbine (GT) exhaust diffuser scale model with performance predicted by commercially available CFD software. The experimental results were obtained from a 1:12 scale model of a GT exhaust diffuser with a fixed row of blades to simulate the swirl generated by the last row of turbine blades five blade configurations. This work is to validate the effect of the turbulent inlet conditions on an axial diffuser, both on the experimental front and on the numerical analysis approach. The object of this work is to bring forward a better understanding of velocity and static pressure profiles along the gas turbine diffusers and to provide an accurate experimental data set to validate the CFD prediction. For the CFD aspect, ANSYS CFX software was chosen as the solver. Two different types of mesh (hexagonal and tetrahedral) will be compared to the experimental results. It is understood that hexagonal (HEX) meshes are more time consuming and more computationally demanding, they are less prone to mesh sensitivity and have the tendancy to converge at a faster rate than the tetrahedral (TET) mesh. It was found that the HEX mesh was able to generate more consistent results and had less error than TET mesh.

Sign in / Sign up

Export Citation Format

Share Document