AC 6-12 Description

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Steam turbine rotor cascade

Application Challenge 6-12               © copyright ERCOFTAC 2004


Description

Introduction

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

A6-12d30 files image002.gif

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.


Table 1 Basic data of the SE 1050 cascade
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



x (mm)
y (mm)
x (mm)
y (mm)
99.999282 0.352723 3.464884 1.225294
99.926424 0.59935 4.753891 2.022511
99.521423 0.815971 6.139122 2.825664
96.001435 2.136338 7.530131 3.572762
92.481447 3.456706 8.921242 4.265414
88.961459 4.777074 10.312443 4.909197
85.441471 6.087441 11.703727 5.508339
81.921483 7.417808 13.095083 6.07044
78.401495 8.738176 14.486504 6.596632
74.881508 10.058544 15.877984 7.091291
71.361520 11.378911 17.269517 7.55728
67.841532 12.699278 18.661100 7.996743
64.321544 14.019646 20.052729 8.411307
60.801556 15.340013 21.444403 8.802027
57.281568 16.660381 22.836120 9.169491
53.761581 17.980748 24.264540 9.520354
50.507366 19.201423 26.037267 9.908534
49.152583 19.702386 28.440150 10.37689
47.520269 20.261961 31.187419 10.839571
45.296321 20.902956 33.971529 11.212068
42.293512 21.587151 36.755824 11.484898
38.685177 22.217304 39.540299 11.661747
35.342716 22.590225 42.324939 11.750299
32.000704 22.723076 45.109726 11.759488
28.683738 22.598581 47.894645 11.697599
25.611367 22.285806 50.679701 11.562528
23.652286 21.966315 53.464905 11.348665
21.977517 21.592001 56.250256 11.05505
20.307477 21.139681 59.035747 10.687274
18.498444 20.555481 61.821342 10.262674
16.828738 19.924468 64.607030 9.789283
15.159193 19.207027 67.392813 9.261068
13.489828 18.392915 70.178720 8.672954
11.681632 17.359536 72.964738 8.021636
10.012817 16.250972 75.750873 7.306083
8.344302 14.981078 78.537134 6.526853
6.676158 13.512223 81.323504 5.686874
4.869618 11.59038 84.109980 4.790667
3.203006 9.300038 86.896902 3.844904
1.600882 6.343956 89.698387 2.853376
0.444430 3.346941 92.489059 1.837071
0.000239 1.258739 94.522906 1.084837
0.053144 0.876155 95.303546 0.812817
0.221685 0.528644 96.096132 0.577871
0.489364 0.250224 96.898907 0.380521
0.829978 0.068148 97.710087 0.221207
1.210186 0.000239 98.527871 0.100282
1.592770 0.053144 99.600827 0.000718
1.946786 0.226249 99.791554 0.039377
2.440690 0.560226 99.937399 0.16822


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


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Description

Test Data

CFD Simulations

Evaluation

Best Practice Advice