Pavel Šafařík

ANALYSIS OF TRANSONIC FLOW PAST CUSPED AIRFOILS

Transonic flow past two cusped airfoils is numerically solved and achieved results are analyzed by means of flow behavior and oblique shocks formation.Regions around sharp trailing edges are studied in detail and parameters of shock waves are solved and compared using classical shock polar approach and verified by reduction parameters for symmetric configurations.

Aerodynamic Investigations of Root Sections of Long Rotor Blades Applied at the Last Stages of Steam Turbines

The aerodynamics of root sections appears to be a crucial problem in the design and operation of the last stages of large output steam turbines. The reasons are transonic flow, high flow turning, and difficulties with keeping their design aerodynamic conditions during operation.Investigations were performed on planar blade cascades representing root sections of 1085mm and 1220mm long rotor blades. The basic conception of the two root sections differs. The aerodynamic loading of the 1220mm blade root section is lowered in order to ensure that the design parameters are kept during turbine stage operation. We present the results of optical and pneumatic measurements i.e. dependencies of the kinetic energy loss coefficient and exit flow angle on the exit isoentropic Mach number and the angle of incidence, as well as images of the flow fields. The experimental data is analyzed in order to assess and document the difference between the two root section designs.Copyright

Transonic Flow Past Plane Cascades: Experimental Data Analysis

The paper presents results from an aerodynamic investigation of transonic flow past profile cascades. The analysis following the experimental data is aimed at transonic effects namely expansion over sonic conditions, aerodynamic choking, supersonic compression accompanying transonic expansion on the suction side, boundary layer development, the flow past a trailing edge, exit shock waves, interaction of shock wave with boundary layer, wakes, etc.

Effects of the Rotor Tip Leakage in a Transonic Turbine With Long Blades

A study of the flow in a transonic turbine stage with long and strongly twisted rotor blades is presented. The focus is on the flow in the near tip region of the blade-to-blade passage of the rotor. The flow has been modelled experimentally in a transonic wind tunnel and numerically by means of 2D and 3D Navier-Stokes equation solvers.The profiles of the rotor cascades are characterized by law turning angles and a high-velocity exit flow. Detailed flow measurements have been carried out and analysed. A comparison has been made between the experimental and numerical results, and is discussed in detail.The design and test data of the flow through the upper sections of the span are presented. The effects of the tip leakage flow are evaluated and the three-dimensional patterns of the main flow are estimated. Other points of interest are the results of 3D Navier-Stokes analysis of the stage flow as compared to 2D simulations and wind tunnel experiments, together with the question of the limitations of the individual methods as they all use approximations to the actual flow in the turbine stage.Copyright

Modelling of Transonic Flow in a Rotor Blade of a Steam Turbine Stage With a High Aspect Ratio Blade

The paper deals with results of a model aerodynamic research of flow in regions of a steam turbine stage with relatively long blades. The flow at design conditions attains transonic velocities and is investigated experimentally in transonic wind tunnel and numerically by means of 3D Euler equations for nonstationary flow. Profile cascades of five different sections of rotor blading were tested and detail flow patterns have been obtained. The experimental data are compared with results of calculations. The study of the operational flow conditions is performed. The results prove that both the tip and the root of the rotor blading are extremely loaded and they are the decisive elements for efficient operation. The middle sections have special profile forms and their aerodynamic design and test data are presented.Copyright