Secondary Flow in Cascades: The Effect of Axial Velocity Ratio

1974 ◽  
Vol 16 (6) ◽  
pp. 402-407 ◽  
Author(s):  
H. Marsh
Keyword(s):  
Secondary Flow ◽  
Incompressible Flow ◽  
Axial Velocity ◽  
Velocity Ratio ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Blade Row ◽  
Flow Through ◽  
The Difference ◽  
Circulation Theorem

By considering the flow through a many-bladed cascade, a simple theory is developed for the effect of a change in axial velocity on the secondary flow at exit from a cascade. An expression is derived for the difference in the time taken for fluid particles to travel over the two surfaces of the blade and this is used, along with Kelvin's circulation theorem for incompressible flow, to obtain an equation for the distributed secondary vorticity. It is shown that for the row of inlet guide vanes tested by Gregory-Smith (1)†, the change of axial velocity across the blade row has a significant effect on the secondary vorticity.

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.

Study on Flow Characteristics Downstream of Annular Inlet Guide Vanes

2013 ◽  
Author(s):  
Masanori Kudo ◽  
Koichi Nishibe ◽  
Masayuki Takahashi ◽  
Kotaro Sato ◽  
Yoshinobu Tsujimoto
Keyword(s):  
Unsteady Flow ◽  
Flow Instability ◽  
Velocity Ratio ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Flow Instabilities ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Flow Oscillations ◽  
Measured Pressure

The main objectives of the present study are to identify the dominant parameters responsible for the generation of unsteady flow, determine the conditions under which flow oscillations are produced and the relation between the flow characteristics and the number of vanes with identical solidity. The flow instabilities downstream of inlet guide vanes (IGV) are clarified experimentally and by numerical simulation. The conditions for the onset of flow instability, including the number of cells and the oscillation characteristics of the unsteady flow, are discussed based on measured pressure fluctuations and the propagating angular velocity ratio of the instability for various radius ratios (r3/r2). The effectiveness of adjusting the number of vanes to control the flow instabilities is also discussed.

The Compressible Flow Through Cascade Actuator Discs

1958 ◽  
Vol 9 (2) ◽  
pp. 110-130 ◽  
Author(s):  
J. H. Horlock
Keyword(s):  
Shear Flow ◽  
Compressible Flow ◽  
Incompressible Flow ◽  
Three Dimensional ◽  
Approximate Solutions ◽  
Two Dimensional ◽  
Guide Vanes ◽  
The Past ◽  
Flow Through ◽  
Annular Cascade

SummaryA theory of the incompressible flow through two- and three-dimensional cascade actuator discs has been developed by several workers over the past ten years, and its accuracy has been confirmed in several experiments. This theory is briefly reviewed, and a parallel theory for subsonic compressible flow through actuator discs is developed. Approximate solutions for several examples are considered, including a compressible shear flow through a two-dimensional cascade, and a compressible flow through an annular cascade of guide vanes.

A Theory for Flow with Axial Symmetry in Centrifugal Impellers

1960 ◽  
Vol 11 (1) ◽  
pp. 22-40
Author(s):  
R. J. Tonks ◽  
A. G. Smith
Keyword(s):  
Velocity Distribution ◽  
Theoretical Calculation ◽  
Centrifugal Compressor ◽  
Incompressible Flow ◽  
Axial Symmetry ◽  
Axial Velocity ◽  
Axial Velocity Distribution ◽  
Flow Through ◽  
Good Agreement

SummaryA theory of incompressible flow with axial symmetry through the impeller of a centrifugal compressor is given more fully and more accurately that by previous writers. The theory is applied to compute the flow through two different impellers. For each design the experimental axial velocity distribution at the impeller eye is in good agreement with that computed numerically from the theory. This means that for the impeller assembly—not untypical of modern designs—considered here, theoretical calculation of intake axial velocity should provide a useful guide to designers.

Paper 32: The Effects of Reynolds Number, Turbulence Intensity, and Axial Velocity Ratio on Compressor Blade Performance

1969 ◽  
Vol 184 (7) ◽  
pp. 93-100
Author(s):  
R. Shaw
Keyword(s):  
Reynolds Number ◽  
Axial Velocity ◽  
Free Stream ◽  
Velocity Ratio ◽  
Compressor Blade ◽  
Free Stream Turbulence ◽  
Blade Row ◽  
Reynolds Number Effects ◽  
Side Walls ◽  
Series Of Experiments

The paper describes a series of experiments that were conducted on a compressor blade of conventional geometry, in a low-speed research compressor, to determine the effect of Reynolds number on the performance of (1) an isolated rotor blade row when the free-stream turbulence is low, (2) the isolated rotor at a higher level of turbulence, and (3) the rotor row when unsteadiness is introduced by a set of inlet guide vanes of zero camber and zero stagger. In each case the axial velocity ratio at mid-span was measured and tests were carried out under similar conditions on a two-dimensional cascade of blades using a wind tunnel with porous side walls. The compressor results indicate that there are significant Reynolds number effects under these conditions, and the comparison with the cascade results demonstrates that there is a difference in performance between the rotating row and the cascade.

Effect of Axial Velocity Variation in Aerofoil Cascades

1971 ◽  
Vol 13 (2) ◽  
pp. 92-99 ◽  
Author(s):  
S. Soundranayagam
Keyword(s):  
Wind Tunnel ◽  
Incompressible Flow ◽  
Axial Velocity ◽  
Three Dimensional ◽  
Velocity Variation ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Two Dimensional Flow ◽  
Wind Tunnel Data ◽  
Flow Through

The effect of the variation of axial velocity in the incompressible flow through a cascade of aerofoils is discussed and it is shown that changes take place in the flow angles and in the blade circulation. A method is proposed by which the effect of axial velocity variation on a known two-dimensional flow or alternatively the two-dimensional equivalent of a flow with axial velocity variation can be calculated. The method is very easy to apply. The deviation may increase or decrease depending on the change in blade circulation and the stagger. An increase in apparent deflection through the cascade can be accompanied by a reduction in the blade force. The method would be particularly useful for the interpretation of cascade wind tunnel data and in the design of impeller stages where three-dimensional flows occur.

Effect of End Wall Contouring on Performance of Ultra-Low Aspect Ratio Transonic Turbine Inlet Guide Vanes

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Toyotaka Sonoda ◽  
Martina Hasenjäger ◽  
Toshiyuki Arima ◽  
Bernhard Sendhoff
Keyword(s):  
Aspect Ratio ◽  
Secondary Flow ◽  
Three Dimensional ◽  
Design Concept ◽  
Guide Vanes ◽  
Low Aspect Ratio ◽  
Inlet Guide Vanes ◽  
Turbine Inlet ◽  
Transonic Turbine ◽  
End Wall

In our previous work on ultralow-aspect ratio transonic turbine inlet guide vanes (IGVs) for a small turbofan engine (Hasenjäger et al., 2005, “Three Dimensional Aerodynamic Optimization for an Ultra-Low Aspect Ratio Transonic Turbine Stator Blade,” ASME Paper No. GT2005-68680), we used numerical stochastic design optimization to propose the new design concept of an extremely aft-loaded airfoil to improve the difficult-to-control aerodynamic loss. At the same time, it is well known that end wall contouring is an effective method for reducing the secondary flow loss. In the literature, both “axisymmetric” and “nonaxisymmetric” end wall geometries have been suggested. Almost all of these geometric variations have been based on the expertise of the turbine designer. In our current work, we employed a stochastic optimization method—the evolution strategy—to optimize and analyze the effect of the axisymmetric end wall contouring on the IGV’s performance. In the optimization, the design of the end wall contour was divided into three different approaches: (1) only hub contour, (2) only tip contour, and (3) hub and tip contour, together with the possibility to observe the correlation between hub/tip changes with regard to their joint influence on the pressure loss. Furthermore, three-dimensional flow mechanisms, related to a secondary flow near the end wall region in the low-aspect ratio transonic turbine IGV, was investigated, based on the above optimization results. A design concept and secondary flow characteristics for the low-aspect ratio full annular transonic turbine IGV is discussed in this paper.

Effect of Endwall Contouring on Performance of Ultra-Low Aspect Ratio Transonic Turbine Inlet Guide Vanes

2007 ◽  
Author(s):  
Toyotaka Sonoda ◽  
Martina Hasenja¨ger ◽  
Toshiyuki Arima ◽  
Bernhard Sendhoff
Keyword(s):  
Aspect Ratio ◽  
Secondary Flow ◽  
Flow Characteristics ◽  
Design Concept ◽  
Guide Vanes ◽  
Low Aspect Ratio ◽  
Inlet Guide Vanes ◽  
Turbine Inlet ◽  
Transonic Turbine ◽  
Endwall Contouring

In our previous work on ultra-low aspect ratio transonic turbine inlet guide vanes for a small turbofan engine [1], we used numerical stochastic design optimization to propose the new design concept of an extremely aft-loaded airfoil to improve the difficult-to-control aerodynamic loss. At the same time, it is well known that endwall contouring is an effective method for reducing the secondary flow loss. In the literature, both “axisymmetric” and “non-axisymmetric” endwall geometries have been suggested. Almost all of these geometric variations have been based on the expertise of the turbine designer. In our current work, we employed a stochastic optimization method — the evolution strategy (ES) — to optimize and analyze the effect of the axisymmetric endwall contouring on the inlet guide vanes’ performance. In the optimization, the design of the endwall contour was divided into three different approaches: 1) only hub contour, 2) only tip contour, and 3) hub and tip contour together with the possibility to observe the correlation between hub/tip changes with regard to their joint influence on the pressure loss. Furthermore, three dimensional flow mechanisms, related to a secondary flow near the endwall region in the low-aspect ratio transonic turbine IGV, was investigated, based on above optimization results. A design concept and secondary flow characteristics for the low-aspect ratio full annular transonic turbine IGV is discussed in this paper.

Some Experiments at Low Speed on Compressor Cascades

1967 ◽  
Vol 89 (3) ◽  
pp. 427-436 ◽  
Author(s):  
D. Pollard ◽  
J. P. Gostelow
Keyword(s):  
Axial Velocity ◽  
Velocity Ratio ◽  
Turbulence Level ◽  
Low Speed ◽  
Pressure Distributions ◽  
Blade Row ◽  
Testing Techniques ◽  
Almost All ◽  
Experimental Pressure ◽  
Good Agreement

Some results of recent work on low-speed cascade tunnels are described. Preliminary investigations, directed toward the analysis and improvement of the airflow and testing techniques, revealed that, when porous sidewall suction was employed, almost all change in axial velocity occurred within the blade row. Variation of axial velocity ratio, aspect ratio, Reynolds number, and turbulence level for one particular cascade facilitated an explanation of differences between the results of early British and American cascade tests. More recently, work has involved cascade tests on an analytically derived cascade. Good agreement was obtained between theoretical and experimental pressure distributions and profile boundary layers.

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