Unsteady Analysis of Inter-Rows Stator-Rotor Spacing Effects on a Transonic, Low-Aspect Ratio Turbine

2015 ◽  
Author(s):  
Etienne Tang ◽  
Gilles Leroy ◽  
Mickaël Philit ◽  
Jacques Demolis
Keyword(s):  
Experimental Data ◽  
Aspect Ratio ◽  
High Pressure Turbine ◽  
Low Aspect Ratio ◽  
Spacing Effects ◽  
Air Turbine ◽  
Flow Features ◽  
Aerodynamic Performances ◽  
Flow Through ◽  
Transonic Turbine

The aerodynamic performances of an axial turbine are affected by the distance between the stator and the rotor. Previous studies have shown different trends, depending mainly on whether the turbine is subsonic or not. The present paper aims at improving the understanding of the effect of rows spacing on the flow through a transonic turbine. A one-stage, low aspect ratio, high pressure turbine case is investigated using CFD. Steady and unsteady phase-lagged RANS computations are performed on this configuration with different inter-blade rows distances. The results are successfully compared with experimental data from a cold air turbine rig. Entropy production balances are used to emphasize the main loss areas and the loss variations caused by changes in inter-blade rows distance. Two techniques are compared for computing these balances, and one of them appears to perform much better. The flow features causing these losses are then identified. Finally, an optimal inter-rows spacing is found. It is a compromise between the losses created by strong stator-rotor interactions at small inter-rows gaps and the losses generated at the endwalls in the inter-rows space at large distances.

The Effect of a Downstream Rotor on the Measured Performance of a Transonic Turbine Nozzle

1986 ◽  
Vol 108 (2) ◽  
pp. 269-274
Author(s):  
R. G. Williamson ◽  
S. H. Moustapha ◽  
J. P. Huot
Keyword(s):  
Performance Evaluation ◽  
Aspect Ratio ◽  
Flow Field ◽  
Large Scale ◽  
Outer Wall ◽  
Nozzle Flow ◽  
Turning Angle ◽  
Low Aspect Ratio ◽  
Transonic Turbine ◽  
Mach Numbers

Two nozzle designs, involving the same low aspect ratio, high turning angle vanes, and differing in outer wall contour, were tested over a range of exit Mach numbers up to supersonic values. The experiments were conducted on a large-scale, full annular configuration with and without a representative rotor downstream. Nozzle performance was found to be significantly affected by rotor operation, the influence depending on the detailed characteristics of the nozzle flow field, as well as on the design and operation of the rotor itself. It is suggested that performance evaluation of low aspect ratio nozzles of high turning angle may require appropriate testing with a rotor.

The Deformational Behaviour of Low Aspect Ratio Multi-Web Wings

1962 ◽  
Vol 13 (1) ◽  
pp. 71-87 ◽  
Author(s):  
R. H. Gallagher ◽  
I. Rattinger
Keyword(s):  
Experimental Data ◽  
Structural Analysis ◽  
Aspect Ratio ◽  
Subsequent Paper ◽  
Plate Bending ◽  
Restricted Range ◽  
Low Aspect Ratio ◽  
Aspect Ratios ◽  
Influence Coefficients ◽  
Geometric Factors

SummaryResults of a study of the accuracy attainable from various approaches to low aspect ratio wing deformational analyses are described. Seven model multi-web wings, representing a restricted range of sweep angles, aspect ratios and other geometric factors, were tested for deflection influence coefficients; Part I gave experimental data. This paper describes, applies, and compares certain elementary and plate bending theories. A subsequent paper will deal with discrete element idealisations commonly employed in matrix structural analysis.

The Deformational Behaviour of Low Aspect Ratio Multi-Web Wings

1962 ◽  
Vol 13 (2) ◽  
pp. 143-166
Author(s):  
R. H. Gallagher ◽  
I. Rattingerj
Keyword(s):  
Experimental Data ◽  
Structural Analysis ◽  
Aspect Ratio ◽  
Plate Bending ◽  
Restricted Range ◽  
Low Aspect Ratio ◽  
Aspect Ratios ◽  
Influence Coefficients ◽  
Geometric Factors ◽  
Analytical Approaches

SummaryResults of a study of the accuracy attainable from various approaches to low aspect ratio wing deformational analysis are described. Seven model multi-web wings, representing a restricted range of sweep angles, aspect ratios and other geometric factors, were tested for deflection influence coefficients and various analytical approaches were applied in the prediction of these results. Part I gave the experimental data; Part II dealt with analyses based on elementary and plate bending theories. This part describes and applies certain discrete element idealisations common to matrix structural analysis. The merits and shortcomings of the theories studied herein are reviewed and other promising approaches are discussed.

MRI investigation and complementary numerical simulations of flow-through random bead packings with low aspect ratio

2005 ◽  
Vol 23 (2) ◽  
pp. 369-370 ◽  
Author(s):  
Claudia Heinen ◽  
Joachim Tillich ◽  
Hans Buggisch ◽  
Thomas Zeiser ◽  
Hannsjörg Freund
Keyword(s):  
Aspect Ratio ◽  
Numerical Simulations ◽  
Low Aspect Ratio ◽  
Flow Through

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.

Three Dimensional Aerodynamic Optimization for an Ultra-Low Aspect Ratio Transonic Turbine Stator Blade

2005 ◽  
Author(s):  
Martina Hasenja¨ger ◽  
Bernhard Sendhoff ◽  
Toyotaka Sonoda ◽  
Toshiyuki Arima
Keyword(s):  
Aspect Ratio ◽  
Static Pressure ◽  
Multi Objective Optimization ◽  
Aerodynamic Loss ◽  
Low Aspect Ratio ◽  
Turbine Stator ◽  
Static Pressure Distribution ◽  
Stator Blade ◽  
Transonic Turbine ◽  
Single Objective

A modern numerical stochastic optimization method, namely the evolution strategy (ES), was applied to an ultra-low aspect ratio transonic turbine stator blade in order to seek a new aerodynamic design concept for lower secondary flow losses. The low stator blade count is selected to avoid the direct viscous interaction of the stator wake with the downstream rotor blade. This led to the ultra-low aspect ratio stator blade. In the optimization, two kinds of objective functions were used, that is, (1) minimization of the “aerodynamic loss” (a single objective), (2) minimization of the “aerodynamic loss” and of the “variation of circumferential static pressure distribution” downstream of the stator blade (multi-objective optimization). In the case of the single objective, the aerodynamic loss is improved by an extreme aft-loaded airfoil with a noticeable bent part near the trailing edge, although the circumferential static distribution is slightly worse than that of the baseline. In the case of the multi-objective optimization, we observe a trade-off relation between aerodynamic loss and variation of static pressure distribution which is not easily resolved. A new design concept to achieve lower aerodynamic loss for ultra-low aspect ratio transonic turbine stator blades is discussed.

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