An experimental evaluation of a low-Reynolds number high-lift airfoil with vanishingly small pitching moment

1989 ◽  
Author(s):  
M. SHEPSHELOVICH ◽  
D. KOSS ◽  
I. WYGNANSKI ◽  
A. SEIFERT
Keyword(s):  
Reynolds Number ◽  
Experimental Evaluation ◽  
Low Reynolds Number ◽  
Pitching Moment ◽  
High Lift ◽  
Low Reynolds

420 Aerodynamic Characteristics and Flow Field of High Lift-to-drag Ratio Airfoils in Low Reynolds Number

2015 ◽  
Vol 2015.68 (0) ◽  
pp. 167-168 ◽  
Author(s):  
Takahiro MAKIZONO ◽  
Gaku SASAKI ◽  
Hiroshi OCHI ◽  
Takaaki MATSUMOTO ◽  
Koichi YONEMOTO
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Low Reynolds Number ◽  
Aerodynamic Characteristics ◽  
High Lift ◽  
Low Reynolds ◽  
Drag Ratio ◽  
Lift To Drag Ratio

A CFD Study of Low Reynolds Number Flow in High Lift Cascades

2010 ◽  
Author(s):  
Roberto Pacciani ◽  
Michele Marconcini ◽  
Andrea Arnone ◽  
Francesco Bertini
Keyword(s):  
Reynolds Number ◽  
Separation Bubble ◽  
Structural Characteristics ◽  
Low Reynolds Number ◽  
Separated Flow ◽  
Flow Region ◽  
Suction Side ◽  
Transitional Region ◽  
High Lift ◽  
Low Reynolds

A study of the separated flow in high-lift, low-Reynolds-number cascade, has been carried out using a novel three-equation, transition-sensitive, turbulence model. It is based on the coupling of an additional transport equation for the so-called laminar kinetic energy with the Wilcox k-ω model. Such an approach takes into account the increase of the non-turbulent fluctuations in the pre-transitional and transitional region. Two high-lift cascades (T106C and T108), recently tested at the von Ka´rma´n Institute in the framework of the European project TATMo (Turbulence and Transition Modelling for Special Turbomachinery Applications), were analyzed. The two cascades have different loading distributions and suction side diffusion rates, and therefore also different separation bubble characteristics and loss levels. The analyzed Reynolds number values span the whole range typically encountered in aeroengines low-pressure turbines operations. Several expansion ratios for steady inflow conditions characterized by different freestream turbulence intensities were considered. A detailed comparison between measurements and computations, including bubble structural characteristics, will be presented and discussed. Results with the proposed model show its ability to predict the evolution of the separated flow region, including bubble bursting phenomena, in high-lift cascades operating in LP-turbine conditions.

scholarly journals An assessment of the laminar kinetic energy concept for the prediction of high-lift, low-Reynolds number cascade flows

2011 ◽  
Vol 225 (7) ◽  
pp. 995-1003 ◽  
Author(s):  
R Pacciani ◽  
M Marconcini ◽  
A Arnone ◽  
F Bertini
Keyword(s):  
Reynolds Number ◽  
Kinetic Energy ◽  
High Speed ◽  
Low Reynolds Number ◽  
Flow Region ◽  
Freestream Turbulence ◽  
High Lift ◽  
Numerical Predictions ◽  
Wide Range ◽  
Low Reynolds

The laminar kinetic energy (LKE) concept has been applied to the prediction of low-Reynolds number flows, characterized by separation-induced transition, in high-lift airfoil cascades for aeronautical low-pressure turbine applications. The LKE transport equation has been coupled with the low-Reynolds number formulation of the Wilcox's k − ω turbulence model. The proposed methodology has been assessed against two high-lift cascade configurations, characterized by different loading distributions and suction-side diffusion rates, and tested over a wide range of Reynolds numbers. The aft-loaded T106C cascade is studied in both high- and low-speed conditions for several expansion ratios and inlet freestream turbulence values. The front-loaded T108 cascade is analysed in high-speed, low-freestream turbulence conditions. Numerical predictions with steady inflow conditions are compared to measurements carried out by the von Kármán Institute and the University of Cambridge. Results obtained with the proposed model show its ability to predict the evolution of the separated flow region, including bubble-bursting phenomenon and the formation of open separations, in high-lift, low-Reynolds number cascade flows.

Calculation of High-Lift Cascades in Low Pressure Turbine Conditions Using a Three-Equation Model

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
Roberto Pacciani ◽  
Michele Marconcini ◽  
Atabak Fadai-Ghotbi ◽  
Sylvain Lardeau ◽  
Michael A. Leschziner
Keyword(s):  
Reynolds Number ◽  
Kinetic Energy ◽  
Eddy Viscosity ◽  
Low Reynolds Number ◽  
Low Pressure ◽  
Equation Model ◽  
Bypass Transition ◽  
High Lift ◽  
Wide Range ◽  
Low Reynolds

A three-equation model has been applied to the prediction of separation-induced transition in high-lift low-Reynolds-number cascade flows. Classical turbulence models fail to predict accurately laminar separation and turbulent reattachment, and usually overpredict the separation length, the main reason for this being the slow rise of the turbulent kinetic energy in the early stage of the separation process. The proposed approach is based on solving an additional transport equation for the so-called laminar kinetic energy, which allows the increase in the nonturbulent fluctuations in the pretransitional and transitional region to be taken into account. The model is derived from that of Lardeau et al. (2004, “Modelling Bypass Transition With Low-Reynolds-Number Non-Linear Eddy-Viscosity Closure,” Flow, Turbul. Combust., 73, pp. 49–76), which was originally formulated to predict bypass transition for attached flows, subject to a wide range of freestream turbulence intensity. A new production term is proposed, based on the mean shear and a laminar eddy-viscosity concept. After a validation of the model for a flat-plate boundary layer, subjected to an adverse pressure gradient, the T106 and T2 cascades, recently tested at the von Kármán Institute, are selected as test cases to assess the ability of the model to predict the flow around high-lift cascades in conditions representative of those in low-pressure turbines. Good agreement with experimental data, in terms of blade-load distributions, separation onset, reattachment locations, and losses, is found over a wide range of Reynolds-number values.

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