Theoretical Studies of Three Dimensional Transonic Flow through a Compressor Blade Row.

1980 ◽  
Author(s):  
William J. Rae
Keyword(s):  
Transonic Flow ◽  
Three Dimensional ◽  
Compressor Blade ◽  
Theoretical Studies ◽  
Blade Row ◽  
Flow Through

Excess Streamwise Vorticity and Its Role in Secondary Flow

1987 ◽  
Vol 201 (6) ◽  
pp. 413-420 ◽  
Author(s):  
P W James
Keyword(s):  
Secondary Flow ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Point Of View ◽  
Streamwise Vorticity ◽  
Three Dimensional Flow ◽  
Approximate Methods ◽  
Blade Row ◽  
Flow Through ◽  
Loss Term

The purpose of this paper is, firstly, to show how the concept of excess secondary vorticity arises naturally from attempts to recover three-dimensional flow details lost in passage-averaging the equations governing the flow through gas turbines. An equation for the growth of excess streamwise vorticity is then derived. This equation, which allows for streamwise entropy gradients through a prescribed loss term, could be integrated numerically through a blade-row to provide the excess vorticity at the exit to a blade-row. The second part of the paper concentrates on the approximate methods of Smith (1) and Came and Marsh (2) for estimating this quantity and demonstrates their relationship to each other and to the concept of excess streamwise vorticity. Finally the relevance of the results to the design of blading for gas turbines, from the point of view of secondary flow, is discussed.

scholarly journals Loss and Deviation in Windmilling Fans

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Ewan J. Gunn ◽  
Cesare A. Hall
Keyword(s):  
Control Volume ◽  
Three Dimensional ◽  
Flow Coefficient ◽  
High Loss ◽  
Pressure Surface ◽  
Blade Row ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Transonic Fan ◽  
Cruise Flight

For an unpowered turbofan in flight, the airflow through the engine causes the fan to freewheel. This paper considers the flow field through a fan operating in this mode, with emphasis on the effects of blade row losses and deviation. A control volume analysis is used to show that windmilling fans operate at a fixed flow coefficient which depends on the blade metal and deviation angles, while the blade row losses are shown to determine the fan mass flow rate. Experimental and numerical results are used to understand how the loss and deviation differ from the design condition due to the flow physics encountered at windmill. Results are presented from an experimental study of a windmilling low-speed rig fan, including detailed area traverses downstream of the rotor and stator. Three-dimensional computational fluid dynamics (CFD) calculations of the fan rig and a representative transonic fan windmilling at a cruise flight condition have also been completed. The rig test results confirm that in the windmilling condition, the flow through the fan stator separates from the pressure surface over most of the span. This generates high loss, and the resulting blockage changes the rotor work profile leading to modified rotational speed. In the engine fan rotor, a vortex forms at the pressure surface near the tip and further loss results from a hub separation caused by blockage from the downstream core and splitter.

The Use of a Finite Difference Technique to Predict Cascade, Stator, and Rotor Deviation Angles and Optimum Angles of Attack

1973 ◽  
Vol 95 (3) ◽  
pp. 185-190 ◽  
Author(s):  
P. R. Dodge
Keyword(s):  
Experimental Data ◽  
Finite Difference ◽  
Velocity Ratio ◽  
Three Dimensional ◽  
Compressor Blade ◽  
Deviation Angle ◽  
Kutta Condition ◽  
Meridional Velocity ◽  
Finite Difference Technique ◽  
Blade Row

This paper develops a method of using a quasi-three-dimensional finite difference (blade to blade) flow program to predict deviation angle. The work discussed herein was accomplished in support of Contract NAS3-15324 with Lewis Research Center of NASA, Cleveland, Ohio. An appropriate approximation to the Kutta Condition is developed. Results are compared with experimental data from cascades including the effects of meridional velocity ratio and compressibility. Predictions are extended to cases with radius changes. In addition, the same program is used to predict optimum angle of attack for a compressor blade row.

Three-Dimensional Lifting-Surface Theory for an Annular Blade Row

1979 ◽  
Author(s):  
G. F. Homicz ◽  
J. A. Lordi
Keyword(s):  
Integral Equation ◽  
Three Dimensional ◽  
Computer Time ◽  
Two Dimensional ◽  
Blade Loading ◽  
Surface Theory ◽  
Lifting Surface ◽  
Strip Theory ◽  
Blade Row ◽  
Flow Through

A lifting-surface analysis is presented for the steady, three-dimensional, compressible flow through an annular blade row. A kernel-function procedure is used to solve the linearized integral equation which relates the unknown blade loading to a specified camber line. The unknown loading is expanded in a finite series of prescribed loading functions which allows the required integrations to be performed analytically, leading to a great savings in computer time. Numerical results are reported for a range of solidities and hub-to-tip ratios; comparisons are made with both two-dimensional strip theory and other three-dimensional results.

A Surface Vorticity Analysis of Three-Dimensional Flow through Strongly Swept Turbine Cascades

1974 ◽  
Vol 16 (6) ◽  
pp. 425-433 ◽  
Author(s):  
D. Graham ◽  
R. I. Lewis
Keyword(s):  
Three Dimensional ◽  
Experimental Tests ◽  
Theoretical Models ◽  
Spanwise Direction ◽  
Three Dimensional Flow ◽  
End Effects ◽  
Dimensional Flow ◽  
Blade Row ◽  
Flow Through ◽  
The Subject

The two-dimensional surface vorticity theory of Martensen is extended to deal with the full three-dimensional flow through a swept turbine cascade, including end effects. Basic concepts of surface vorticity theories are dealt with initially, as also are three three-dimensional flow considerations for swept cascades. The paper goes on to develop two theoretical models for the representation of swept blade row flows. The first model assumes that the blade bound vorticity remains constant across the span of the blade. In the second model, this assumption is relaxed so that the blade bound vorticity is allowed to vary in the spanwise direction. In both cases the theories are applied to turbine nozzle cascades. Some of the solutions obtained are compared with experimental tests which were the subject of a previous paper.

Linearized Solutions for the Supersonic Flow Through Turbomachinery Blade Rows (Using Actuator Disk Theory)

1980 ◽  
Vol 102 (3) ◽  
pp. 330-337
Author(s):  
J. H. Horlock ◽  
C. F. Grainger
Keyword(s):  
Supersonic Flow ◽  
Method Of Characteristics ◽  
Three Dimensional ◽  
Actuator Disk ◽  
Blade Row ◽  
Flow Through ◽  
Twisted Blade ◽  
Disk Method

An actuator disk method is developed for calculating the flow through the blade rows of a turbomachine in which the velocity relative to the blading may be supersonic. The method is compared with calculations of the fully supersonic flow through a twisted blade row using a three-dimensional method of characteristics.

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