AC 6-12 Description
Steam turbine rotor cascade
Application Challenge 6-12 © copyright ERCOFTAC 2004
The results of experimental investigation of fluid flow in blade cascades at transonic flow regimes are invaluable for improvements of turbine designs and for verification of CFD codes. Higher efficiency and operational reliability of turbines and compressors can be reach by coupling of experimental and numerical modelling of flow in cascades.
The transonic flow in a steam turbine rotor cascade was selected for the application challenge. The investigation of the SE 1050 blade cascade includes experimental test data based on interferometric pictures of fluid flow and numerical simulation using models of inviscid flow (home-made software) and of viscous flow (FLUENT code).
As the testcase, the measurement for the inlet angle β1 = 70.7 deg and the exit isentropic Mach numbers 1.198 was chosen. The basic series of measurements was made for the inlet angle β1 = 70.7 deg (incidence i = 0 deg) with the exit isentropic Mach numbers changed in the range (0.489, 1.387). Some additional experiments were carried out for extreme values of incidence covering the range from very small loading to overloading conditions.
Relevance to Industrial Sector
The blade cascades belong to most important elements in turbomachinery and their design is crucial for the efficiency and operational reliability of turbines and compressors. This is valid especially for turbines of large output. The chosen profile cascade called SE 1050 was designed for the last stage of a SKODA steam turbine with the blade length 1085 mm and a nominal speed of 3000 rpm. The SE 1050 profile is a section of a rotor blade at the distance 320 mm from the root. The cascade operated in the transonic regime was chosen as the testcase suitable for testing of numerical methods and verification of experimental methods as well.
Design or Assessment Parameters
Following parameters are used as crucial for the appraisal of CFD calculations:
- isolines of the Mach number and/or density in the flow field of the blade cascade
- pressure and Mach number distribution on the profile surface
- energy losses
- exit flow angle
Flow Domain Geometry
Fig.1 Scheme of the SE 1050 blade cascade
The scheme of the cascade is given in Fig.1. The basic data of the cascade and coordinates of the profile SE 1050 are given in Tables 1 and 2.
|chord b||100 mm|
|blade span||160 mm|
|pitch t||55.12 mm|
|stagger angle ?||37.11 deg|
|number of blades||8|
|inlet angle ß1||70.7 deg|
|incidence angle i||0 deg|
Flow Physics and Fluid Dynamics Data
The compressible adiabatic flow in the blade cascade is mostly laminar with the transition to turbulence in the exit part of the cascade. The fluid flow is accelerated in the blade passage. Air is considered as a perfect gas. The governing parameters are as follows:
- inlet Mach number
- inlet flow angle
- isentropic outlet Mach number
- outlet Reynolds number based on profile chord
© copyright ERCOFTAC 2004
Contributors: Jaromir Prihoda; Karel Kozel - Czech Academy of Sciences