Milan Matejka

Influence of Active Methods of Flow Control on Compressor Blade Cascade Flow

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.© 2008 ASME

Loss Coefficient Dependence of Turbine Blade Cascade

This paper presents the experimental results of aerodynamic research performed on a blade cascade representing the midsection of 1220 mm long rotor blades of the last stage of a large output steam turbine. The operational regime of the blade cascade is characterized by supersonic exit velocity. Isentropic exit Mach number M2is = 1.323. The experimental data analysis concerns pneumatic measurements to calculate the total pressure and the kinetic energy loss coefficients, and to evaluate them mainly with respect to the aperiodicity of the flow field. The flow structure is also studied on the basis of results obtained by means of optical methods, such as schlieren and interferometric methods.Copyright

Experimental Results of Synthetic Jet Wind Tunnel Tests

This chapter deals with the results of experimental data of synthetic jet flow control. The effect of synthetic jet generator design on output jet velocity and intensity and hot-wire software development and experimental results are discussed. Two different arrangements of experiments show the difference between piezo and electrodynamic actuator as driver of synthetic jet generator.

Introduction to the Synthetic Jet Flow Control and Drag Reduction Techniques

This chapter deals with the preliminary design of a synthetic jet generator. The effect of the synthetic jet strongly depends on its frequency, which should correspond to the natural vortex shedding frequency of the flow. This frequency can be found using the Strouhal number (nondimensional frequency). The design of a synthetic jet generator must take into account the vortex shedding frequency and acoustic properties of generator. The lumped element model (LEM), which is based on an analogy between electrical and acoustic domains, may be applied in the preliminary design of a synthetic jet generator. LEM is particularly useful in determining the amplitude-frequency characteristic (output velocity x frequency) of the synthetic jet actuator.