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Experimental Data on High-Speed Flow Past the Root Blade Cascade
Šimurda, David ; Luxa, Martin ; Synáč, J. ; Šafařík, P.
The paper deals with experimental results of high-speed aerodynamic research on a blade cascade. The blade cascade represents root section of the last stage rotor blades of large output steam turbine. Basic aerodynamic characteristics of the blade cascade are presented together with photographs of flow fields in the range of transonic flow regimes. Results are analysed and discussed to provide a new knowledge on design and operation of the last rotor at the region of the blade root.
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Numerical and experimental modelling of transition in a separated boundary layer on the NACA63A421 airfoil
Ďuriš, M. ; Popelka, Lukáš ; Příhoda, Jaromír ; Šimurda, David
The paper is concerned with numerical modelling of transition in a separated boundary layer. A transition model is based on the combination of empirical terms determining position of the transition and averaged Navier–Stokes equations closed by SST turbulence model. The model of transition is applied in computation of 2D flow past NACA63A421 airfoil. Computation is performed using commercial code Fluent 6.3.26, in which the transition model is implemented as a User-Defined-Function. Computed distributions of the pressure coefficient along the airfoil are verified by comparison with experimental data, which were obtained by measurements in a closed circuit wind tunnel at the constant Reynolds number and several angles of attack. The comparison proves the applicability of the implemented transition model.
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PASSIVE CONTROL OF BOUNDARY LAYER TRANSITION AND SEPARATION
Popelka, Lukáš ; Matějka, M. ; Šimurda, David ; Součková, Natálie
Particle Image Velocimetry, smoke-wire, tuft filaments and oil-flow visualization techniques were used for wind-tunnel and in-flight investigation of boundary layer separation, both stall and separation bubbles, related to the low-Reynolds number transition mechanism. Airfoils of three Czech-designed sailplanes and their wing-fuselage interaction were subject to study. Experimental data were coupled with numerical modeling and synthesis gained. Effect of passive flow control devices - vortex generators - was surveyed, counter-rotating vortex generators and Zig-zag type turbulators were applied. Separation suppression was reached and consequent drag coefficient reduction of test aircrafts measured in flight. Investigation was further extended by PIV Time-Resolved technique.
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