This paper deals with active methods of flow control, especially synthetic jet flow control. A synthetic jet was used for flow control in the compressor blade cascade to reduce the vortex structure and reduce the value of the loss coefficients. The output slot of the synthetic jet actuator was situated on the side wall on the connecting line of the leading edges of the blades. The direction of the synthetic jet was perpendicular to the main flow. The synthetic jet excitation is more effective and more efficient than a steady blowing or suction, and its great advantage is zero mass flux supplied to, or taken from the main flow. A positive influence of the synthetic jet on the flow field was proved. The flow field was also visualized.
Flow visualization techniques often enable the first insight into the investigated problem. Generally, the particle image velocimetry, smoke-wire, tuft filaments and oil-flow visualization techniques are used for wind-tunnel investigation. Considering the phenomenon of boundary layer separation bubble related to the low-Reynolds number's transition, these methods face several difficulties mainly with imposed influence to the sensitive flow mechanism. Infrared imaging allowing non-invasive visualization of the afore-mentioned investigations is one of the techniques currently undergoing further promising development in terms of resolution, device size, and price. In the presented paper, the focus was placed on validation of the infrared imaging as a standard visualization technique for wind-tunnel investigation of boundary layer development along an airfoil and its usage for roughness-due-to-insect investigation.
Wind-tunnels and in-flight measurements on sailplanes were carried out and effect of passive flow control devices -vortex generators -was surveyed; namely counter-rotating vortex generators and Zig-zag type turbulators were applied. Separation suppression and consequent drag coefficient reduction of test aircrafts was reached. PIV investigation was further extended by Time-Resolved techniques.An important study on structure of the turbulent flow in the lower atmosphere, creating an environment of the soaring flight, was presented.
The results of experimental study on a boundary layer separation control are given in the paper. The boundary layer on a flat wall is subjected to adverse pressure gradient. The active control strategy evolving a synthetic jet has been applied. The separation process is investigated using TR-PIV method. Dynamical aspects of the phenomenon are analyzed in details.
This paper describes comparison between 3D CFD calculation of labyrinth seal of a turbine engine and measurement of actual advanced turbine engine in test facility. The goal is to verify capability of the 3D CFD modelling and obtain more insight into air flow path in the labyrinth seal. The total temperature was revealed not being a constant value through the labyrinth seal, thus driving design and even service trend monitoring consequences.
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