Pneumatic Measurements Downstream of a Radial Turbine Nozzle Cascade

This paper deals mainly with pneumatic measurements on a radial turbine nozzle cascade. The fill radial cascade guarantees the exit flow field periodicity downstream of it. A special traversing mechanism with a five - hole conical probe moving along a circular path behind the cascade was used for flow field investigation in this type of cascade with very low aspect ratio. The analyses of results of 2D and 3D pneumatic measurements including loss coefficient values are presented.

Optimization of Root Section for Ultra-long Steam Turbine Rotor Blade

This study presents the comparison of aerodynamic performances of two successive designs of the root profiles for the ultra-long rotor blade equipped with a straight fir-tree dovetail. Since aerodynamic and strength requirements laid upon the root section design are contradictory, it is necessary to aerodynamically optimize the design within the limits given by the foremost strength requirements. The most limiting criterion of the static strength is the size of the blade cross-section, which is determined by the number of blades in a rotor and also by the shape and size of a blade dovetail. The aerodynamic design requires mainly the zero incidence angle at the inlet of a profile and in the ideal case ensures that the load does not exceed a limit load condition. Moreover, the typical root profile cascades are transonic with supersonic exit Math number, therefore, the shape of a suction side and a trailing edge has to respect transonic expansion of a working gas. In this paper, the two variants of root section profile cascades are compared and the aerodynamic qualities of both variants are verified using CFD simulation and two mutually independent experimental methods of measurements （optical and pneumatic）.

Investigation of the Compressible Flow through the Tip-Section Turbine Blade Cascade with Supersonic Inlet

The contribution deals with the experimental and numerical investigation of compressible flow through the tip-section turbine blade cascade with the blade 54″ long. Experimental investigations by means of optical(interferometry and schlieren method) and pneumatic measurements provide more information about the behaviour and nature of basic phenomena occurring in the profile cascade flow field. The numerical simulation was carried out by means of the EARSM turbulence model according to Hellsten [5] completed by the bypass transition model with the algebraic equation for the intermittency coefficient proposed by Straka and P?íhoda [6] and implemented into the in-house numerical code. The investigation was focused particularly on the effect of shock waves on the shear layer development including the laminar/turbulent transition. Interactions of shock waves with shear layers on both sides of the blade result usually in the transition in attached and/ or separated flow and so to the considerable impact to the flow structure and energy losses in the blade cascade.

Mathematical Modelling and Experimental Investigation of Gas Flow in Minichannels and Microchannels

The first part of this study is focused on the numerical modelling and experimental investigation of transonic flow through a 2D model of the male rotor-housing gap in a dry screw compressor.Numerical simulations of the clearance flow are performed with the help of the in-house compressible Navier-Stokes solver.Experimental measurements based on the Schlieren method in Toepler configuration are carried out.The objective of the second part of the study is to derive the analytical solution of gas microflow development in a gap between two parallel plates.The microflow is assumed to be laminar,incompressible and the velocity slip boundary conditions are considered at the walls.The constant velocity profile is prescribed at the inlet.For the mathematical description of the problem,the Oseen equation is used.The analytical results are compared with the numerical ones obtained using the developed incompressible Navier-Stokes solver including the slip flow boundary conditions.