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{{AC|front=AC 6-12|description=AC 6-12 Description|testdata=AC 6-12 Test Data|cfdsimulations=AC 6-12 CFD Simulations|evaluation=AC 6-12 Evaluation|qualityreview=AC 6-12 Quality Review|bestpractice=AC 6-12 Best Practice Advice|relatedACs=AC 6-12 Related ACs}}
{{AC|front=AC 6-12|description=AC 6-12 Description|testdata=AC 6-12 Test Data|cfdsimulations=AC 6-12 CFD Simulations|evaluation=AC 6-12 Evaluation|qualityreview=AC 6-12 Quality Review|bestpractice=AC 6-12 Best Practice Advice|relatedUFRs=AC 6-12 Related ACs}}




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== Overview of Tests ==
== Overview of Tests ==


Experiments were carried out in the wind tunnel in the High-Speed Laboratory of the Institute of Thermomechanics AS CR in Prague. The blown-down wind tunnel connected to the vacuum storage (6500 m<sup>3</sup>) has a turnable test section that is 160 mm in width and 220 600 mm in height depending on the cascade stagger. The maximum error of inlet angle setting is 0.1 deg. The experimental facility provides the possibility of pneumatic and optical measurements in the range of Mach numbers up to M &asymp; 2. The tunnel is equipped with a Mach-Zehnder interferometer (mirror &Oslash; 156 mm) and schlieren optics, both can be used either with a nanosecond spark source or a Video system. A semi-automatic traversing device together with a digital measuring system is used to measure cascade losses as well as other aerodynamic data. The tunnel is especially suited for turbine cascades which can be measured within the range of exit Mach numbers (0.5; 2) and inlet angles &beta;<sub>1</sub> (30 deg; 150 deg).
Experiments were carried out in the wind tunnel in the High-Speed Laboratory of the Institute of Thermomechanics AS CR in Prague. The blown-down wind tunnel connected to the vacuum storage (6500 m<sup>3</sup>) has a turnable test section that is 160 mm in width and 220 &ndash; 600 mm in height depending on the cascade stagger. The maximum error of inlet angle setting is 0.1 deg. The experimental facility provides the possibility of pneumatic and optical measurements in the range of Mach numbers up to M &asymp; 2. The tunnel is equipped with a Mach-Zehnder interferometer (mirror &Oslash; 156 mm) and schlieren optics, both can be used either with a nanosecond spark source or a Video system. A semi-automatic traversing device together with a digital measuring system is used to measure cascade losses as well as other aerodynamic data. The tunnel is especially suited for turbine cascades which can be measured within the range of exit Mach numbers (0.5; 2) and inlet angles &beta;<sub>1</sub> (30 deg; 150 deg).


The SE 1050 blade cascade was designed for the inlet flow angle &beta;<sub>1</sub> = 70.7 deg, the isentropic exit Mach number M<sub>2is</sub> = 1.208 and for wet steam. The flow in the blade cascade was investigated within a wide range of exit Mach numbers and inlet angles by the Mach-Zehnder interferometer.
The SE 1050 blade cascade was designed for the inlet flow angle &beta;<sub>1</sub> = 70.7 deg, the isentropic exit Mach number M<sub>2is</sub> = 1.208 and for wet steam. The flow in the blade cascade was investigated within a wide range of exit Mach numbers and inlet angles by the Mach-Zehnder interferometer.


Test data are based on interferometric pictures taken for various flow conditions. The density difference between two adjacent fringes is given by the wave length of monochromatic light and the wind tunnel width by the relation &Delta;&rho; = 0.011858 kg/m<sup>3</sup>. Detailed description of the evaluation procedure is given by Šafařík (1996). The basic series was made for the inlet angle &beta;<sub>1</sub> = 70.7 deg (incidence i = 0 deg) with the exit isentropic Mach numbers changed in the range (0.489, 1.387). Measurements were carried out for following values of Mach numbers:
Test data are based on interferometric pictures taken for various flow conditions. The density difference between two adjacent fringes is given by the wave length of monochromatic light and the wind tunnel width by the relation &Delta;&rho; = 0.011858 kg/m<sup>3</sup>. Detailed description of the evaluation procedure is given by &#352;afařík (1996). The basic series was made for the inlet angle &beta;<sub>1</sub> = 70.7 deg (incidence i = 0 deg) with the exit isentropic Mach numbers changed in the range (0.489, 1.387). Measurements were carried out for following values of Mach numbers:




{| style="border-collapse: collapse"
{|align="center" border="1" width="600"
| style="width: 44.45pt; padding: 0cm 3.5pt 0cm 3.5pt" width="59" valign="top" |
!align="center"|i(deg)
''' i (deg) '''
!align="center"|M<sub>1</sub>
| style="width: 40.15pt; padding: 0cm 3.5pt 0cm 3.5pt" width="54" valign="top" |
!align="center"|M<sub>2is</sub>
''' M<sub>1</sub> '''
!width="60"|
| style="width: 48.55pt; padding: 0cm 3.5pt 0cm 3.5pt" width="65" valign="top" |
!align="center"|i(deg)
''' M<sub>2is</sub> '''
!align="center"|M<sub>1</sub>
| style="width: 1.0cm; padding: 0cm 3.5pt 0cm 3.5pt" width="38" valign="top" |
!align="center"|M<sub>2is</sub>
''' '''
| style="width: 44.45pt; padding: 0cm 3.5pt 0cm 3.5pt" width="59" valign="top" |
''' i (deg) '''
| style="width: 40.15pt; padding: 0cm 3.5pt 0cm 3.5pt" width="54" valign="top" |
''' M<sub>1</sub> '''
| style="width: 54.35pt; padding: 0cm 3.5pt 0cm 3.5pt" width="72" valign="top" |
''' M<sub>2is</sub> '''
|-
|-
| style="width: 44.45pt; padding: 0cm 3.5pt 0cm 3.5pt" width="59" valign="top" |
|align="center"|0||align="center"|0.279||align="center"|0.489||
''' 0 '''
|align="center"|0||align="center"|0.376||align="center"|1.007
| style="width: 40.15pt; padding: 0cm 3.5pt 0cm 3.5pt" width="54" valign="top" |
''' 0.279 '''
| style="width: 48.55pt; padding: 0cm 3.5pt 0cm 3.5pt" width="65" valign="top" |
''' 0.489 '''
| style="width: 1.0cm; padding: 0cm 3.5pt 0cm 3.5pt" width="38" valign="top" |
''' '''
| style="width: 44.45pt; padding: 0cm 3.5pt 0cm 3.5pt" width="59" valign="top" |
''' 0 '''
| style="width: 40.15pt; padding: 0cm 3.5pt 0cm 3.5pt" width="54" valign="top" |
''' 0.376 '''
| style="width: 54.35pt; padding: 0cm 3.5pt 0cm 3.5pt" width="72" valign="top" |
''' 1.007 '''
|-
|-
| style="width: 44.45pt; padding: 0cm 3.5pt 0cm 3.5pt" width="59" valign="top" |
|align="center"|0||align="center"|0.322||align="center"|0.610||
''' 0 '''
|align="center"|0||align="center"|0.376||align="center"|1.099
| style="width: 40.15pt; padding: 0cm 3.5pt 0cm 3.5pt" width="54" valign="top" |
''' 0.322 '''
| style="width: 48.55pt; padding: 0cm 3.5pt 0cm 3.5pt" width="65" valign="top" |
''' 0.610 '''
| style="width: 1.0cm; padding: 0cm 3.5pt 0cm 3.5pt" width="38" valign="top" |
''' '''
| style="width: 44.45pt; padding: 0cm 3.5pt 0cm 3.5pt" width="59" valign="top" |
''' 0 '''
| style="width: 40.15pt; padding: 0cm 3.5pt 0cm 3.5pt" width="54" valign="top" |
''' 0.376 '''
| style="width: 54.35pt; padding: 0cm 3.5pt 0cm 3.5pt" width="72" valign="top" |
''' 1.099 '''
|-
|-
| style="width: 44.45pt; padding: 0cm 3.5pt 0cm 3.5pt" width="59" valign="top" |
|align="center"|0||align="center"|0.354||align="center"|0.716||
''' 0 '''
|align="center"|0||align="center"|0.375||align="center"|1.198
| style="width: 40.15pt; padding: 0cm 3.5pt 0cm 3.5pt" width="54" valign="top" |
''' 0.354 '''
| style="width: 48.55pt; padding: 0cm 3.5pt 0cm 3.5pt" width="65" valign="top" |
''' 0.716 '''
| style="width: 1.0cm; padding: 0cm 3.5pt 0cm 3.5pt" width="38" valign="top" |
''' '''
| style="width: 44.45pt; padding: 0cm 3.5pt 0cm 3.5pt" width="59" valign="top" |
''' 0 '''
| style="width: 40.15pt; padding: 0cm 3.5pt 0cm 3.5pt" width="54" valign="top" |
''' 0.375 '''
| style="width: 54.35pt; padding: 0cm 3.5pt 0cm 3.5pt" width="72" valign="top" |
''' 1.198 '''
|-
|-
| style="width: 44.45pt; padding: 0cm 3.5pt 0cm 3.5pt" width="59" valign="top" |
|align="center"|0||align="center"|0.364||align="center"|0.793||
''' 0 '''
|align="center"|0||align="center"|0.379||align="center"|1.313
| style="width: 40.15pt; padding: 0cm 3.5pt 0cm 3.5pt" width="54" valign="top" |
''' 0.364 '''
| style="width: 48.55pt; padding: 0cm 3.5pt 0cm 3.5pt" width="65" valign="top" |
''' 0.793 '''
| style="width: 1.0cm; padding: 0cm 3.5pt 0cm 3.5pt" width="38" valign="top" |
''' '''
| style="width: 44.45pt; padding: 0cm 3.5pt 0cm 3.5pt" width="59" valign="top" |
''' 0 '''
| style="width: 40.15pt; padding: 0cm 3.5pt 0cm 3.5pt" width="54" valign="top" |
''' 0.379 '''
| style="width: 54.35pt; padding: 0cm 3.5pt 0cm 3.5pt" width="72" valign="top" |
1.313
|-
|-
| style="width: 44.45pt; padding: 0cm 3.5pt 0cm 3.5pt" width="59" valign="top" |
|align="center"|0||align="center"|0.365||align="center"|0.906||
''' 0 '''
|align="center"|0||align="center"|0.377||align="center"|1.387
| style="width: 40.15pt; padding: 0cm 3.5pt 0cm 3.5pt" width="54" valign="top" |
''' 0.365 '''
| style="width: 48.55pt; padding: 0cm 3.5pt 0cm 3.5pt" width="65" valign="top" |
''' 0.906 '''
| style="width: 1.0cm; padding: 0cm 3.5pt 0cm 3.5pt" width="38" valign="top" |
''' '''
| style="width: 44.45pt; padding: 0cm 3.5pt 0cm 3.5pt" width="59" valign="top" |
''' 0 '''
| style="width: 40.15pt; padding: 0cm 3.5pt 0cm 3.5pt" width="54" valign="top" |
''' 0.377 '''
| style="width: 54.35pt; padding: 0cm 3.5pt 0cm 3.5pt" width="72" valign="top" |
''' 1.387 '''
|}
|}


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The case corresponding to nearly design conditions with M<sub>2is</sub>=1.198 was chosen for the Application Challenge.
The case corresponding to nearly design conditions with M<sub>2is</sub>=1.198 was chosen for the Application Challenge.


The measurement covers the values from low subsonic to supersonic exit velocities including the transonic region. Additional experiments were carried out for extreme values of incidence i = 70.7 -– &beta;<sub>1</sub> covering the range from i = – 67 deg (very small loading) to i = +30 deg (overloading conditions).
The measurement covers the values from low subsonic to supersonic exit velocities including the transonic region. Additional experiments were carried out for extreme values of incidence i = 70.7 -&beta;<sub>1</sub> covering the range from i = -67 deg (very small loading) to i = +30 deg (overloading conditions).






{| style="border-collapse: collapse"
{|align="center" border="1" width="200"
| style="width: 58.65pt; padding: 0cm 3.5pt 0cm 3.5pt" width="78" valign="top" |
!align="center"|i (deg)
<center>'''i (deg)'''</center>
!align="center"|M<sub>1</sub>
| style="width: 62.75pt; padding: 0cm 3.5pt 0cm 3.5pt" width="84" valign="top" |
!align="center"|M<sub>2is</sub>
<center>'''M<sub>1</sub>'''</center>
| style="width: 54.35pt; padding: 0cm 3.5pt 0cm 3.5pt" width="72" valign="top" |
'''M<sub>2is</sub>'''
|-
|-
| style="width: 58.65pt; padding: 0cm 3.5pt 0cm 3.5pt" width="78" valign="top" |
|align="center"|-67||align="center"|0.545||align="center"|0.905
<center>– 67</center>
| style="width: 62.75pt; padding: 0cm 3.5pt 0cm 3.5pt" width="84" valign="top" |
<center>0.545</center>
| style="width: 54.35pt; padding: 0cm 3.5pt 0cm 3.5pt" width="72" valign="top" |
0.905
|-
|-
| style="width: 58.65pt; padding: 0cm 3.5pt 0cm 3.5pt" width="78" valign="top" |
|align="center"|+30||align="center"|0.660||align="center"|1.012
<center>+ 30</center>
| style="width: 62.75pt; padding: 0cm 3.5pt 0cm 3.5pt" width="84" valign="top" |
<center>0.660</center>
| style="width: 54.35pt; padding: 0cm 3.5pt 0cm 3.5pt" width="72" valign="top" |
1.012
|}
|}




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=== Description of Experiment ===
=== Description of Experiment ===


The flow regime near the design conditions (the inlet angle β<sub>1</sub> = 70.7 deg and the isentropic exit Mach number M<sub>2is</sub> = 1.198) was accepted to be the test case EXP1. The relevant parameters are given in the Table EXP-A.<br clear="all" />
The flow regime near the design conditions (the inlet angle &beta;<sub>1</sub> = 70.7 deg and the isentropic exit Mach number M<sub>2is</sub> = 1.198) was accepted to be the test case EXP1. The relevant parameters are given in the Table EXP-A.<br clear="all" />


=== Boundary Data ===
=== Boundary Data ===
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Inlet conditions are characterized by the total pressure and the total temperature upstream the cascade. The flow regime was adjusted by means of the back pressure in the settling chamber downstream the cascade. The back pressure was controlled by the throttling valve.
Inlet conditions are characterized by the total pressure and the total temperature upstream the cascade. The flow regime was adjusted by means of the back pressure in the settling chamber downstream the cascade. The back pressure was controlled by the throttling valve.


The profiles of the blade cascade were manufactured in high precision. The surface was smooth (glossy steel).<br clear="all" />
The profiles of the blade cascade were manufactured in high precision. The surface was smooth (glossy steel).
 
<br clear="all" />


=== Measurement Errors ===
=== Measurement Errors ===


The dependence of Mach number errors on the value of the inlet Mach number was derived for interferometric measurements. The Mach number error can be estimated as δM = 0.005 for the Mach number M &asymp; 1.
The dependence of Mach number errors on the value of the inlet Mach number was derived for interferometric measurements. The Mach number error can be estimated as &delta;M = 0.005 for the Mach number M &asymp; 1.


The errors of pressure and temperature were δP = 70 Pa and δT = 0.1 K. The error analysis of the data reduction method for the evaluation of the exit angle and the kinetic energy loss coefficient has not been carried out. The maximum error of the exit angle was estimated to be about 0.3 deg.
The errors of pressure and temperature were &delta;P = 70 Pa and &delta;T = 0.1 K. The error analysis of the data reduction method for the evaluation of the exit angle and the kinetic energy loss coefficient has not been carried out. The maximum error of the exit angle was estimated to be about 0.3 deg.


=== Measured Data ===
=== Measured Data ===


EXP1 Measurement of flow in the steam turbine rotor cascade: interferogram of the flow field, pressure distribution on the blade, survey of relevant parameters (given in the file [http://qnetkb.cfms.org.uk/TA6/AC6-12/X/exp12.dat exp12.dat])
EXP1 Measurement of flow in the steam turbine rotor cascade: interferogram of the flow field, pressure distribution on the blade, survey of relevant parameters (given in the file [[media:AC6-12_exp12.dat|exp12.dat]])


The files containing results with measured and evaluated parameters are given in Table EXP-B:
The files containing results with measured and evaluated parameters are given in Table EXP-B:


[I/exp11.jpg exp11.jpg] (interferogram with density isolines for M<sub>2is</sub> = 1.198)
[[media:AC6-12_exp11.jpg|exp11.jpg]] (interferogram with density isolines for M<sub>2is</sub> = 1.198)


[http://qnetkb.cfms.org.uk/TA6/AC6-12/X/exp12.dat exp12.dat] (survey of relevant parameters β<sub>1</sub>, i, M<sub>1</sub>, M<sub>2is</sub>, Re<sub>2is</sub>, ζ, β<sub>2</sub>, p<sub>01</sub>, T<sub>01</sub>, pressure distribution on the suction and pressure sides p/p0 vers. x/b )
[[media:AC6-12_exp12.dat|exp12.dat]] (survey of relevant parameters &beta;<sub>1</sub>, i, M<sub>1</sub>, M<sub>2is</sub>, Re<sub>2is</sub>, &zeta;, &beta;<sub>2</sub>, p<sub>01</sub>, T<sub>01</sub>, pressure distribution on the suction and pressure sides p/p0 vers. x/b)


{| style="margin-left: 18.0pt; border-collapse: collapse"
{| style="margin-left: 18.0pt; border-collapse: collapse"
|+ Table EXP-A Summary description of all test cases
| style="width: 21.35pt; border: solid windowtext 1.0pt; padding: 0cm 3.5pt 0cm 3.5pt" width="28" valign="top" |
| style="width: 21.35pt; border: solid windowtext 1.0pt; padding: 0cm 3.5pt 0cm 3.5pt" width="28" valign="top" |
<center>''Name''</center>
<center>''Name''</center>
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|-
|-
| style="width: 21.35pt; border: solid windowtext 1.0pt; border-top: none; padding: 0cm 3.5pt 0cm 3.5pt" width="28" valign="top" |
| style="width: 21.35pt; border: solid windowtext 1.0pt; border-top: none; padding: 0cm 3.5pt 0cm 3.5pt" width="28" valign="top" |
<center> </center>
<center> </center>
| style="width: 56.4pt; border-top: none; border-left: none; border-bottom: solid windowtext 1.0pt; border-right: solid windowtext 1.0pt; padding: 0cm 3.5pt 0cm 3.5pt" width="75" valign="top" |
| style="width: 56.4pt; border-top: none; border-left: none; border-bottom: solid windowtext 1.0pt; border-right: solid windowtext 1.0pt; padding: 0cm 3.5pt 0cm 3.5pt" width="75" valign="top" |
<center>Re</center>
<center>Re</center>
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<center>inlet angle</center>
<center>inlet angle</center>


<center>β<sub>1</sub> (deg)</center>
<center>&beta;<sub>1</sub> (deg)</center>
| style="width: 77.95pt; border-top: none; border-left: none; border-bottom: solid windowtext 1.0pt; border-right: solid windowtext 1.0pt; padding: 0cm 3.5pt 0cm 3.5pt" width="104" valign="top" |
| style="width: 77.95pt; border-top: none; border-left: none; border-bottom: solid windowtext 1.0pt; border-right: solid windowtext 1.0pt; padding: 0cm 3.5pt 0cm 3.5pt" width="104" valign="top" |
<center>total pressure</center>
<center>total pressure</center>
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<center>detailed data</center>
<center>detailed data</center>


<center>ρ (kg/m<sup>3</sup>)</center>
<center>&rho; (kg/m<sup>3</sup>)</center>
| style="width: 63.45pt; border-top: none; border-left: none; border-bottom: solid windowtext 1.0pt; border-right: solid windowtext 1.0pt; padding: 0cm 3.5pt 0cm 3.5pt" width="85" valign="top" |
| style="width: 63.45pt; border-top: none; border-left: none; border-bottom: solid windowtext 1.0pt; border-right: solid windowtext 1.0pt; padding: 0cm 3.5pt 0cm 3.5pt" width="85" valign="top" |
<center>[../../help/glossary.htm DOAP]s</center>
<center>[../../help/glossary.htm DOAP]s</center>
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<center>ρ=f(x,y)</center>
<center>ρ=f(x,y)</center>


<center> </center>
| style="width: 63.45pt; border-top: none; border-left: none; border-bottom: solid windowtext 1.0pt; border-right: solid windowtext 1.0pt; padding: 0cm 3.5pt 0cm 3.5pt" width="85" valign="top" |
| style="width: 63.45pt; border-top: none; border-left: none; border-bottom: solid windowtext 1.0pt; border-right: solid windowtext 1.0pt; padding: 0cm 3.5pt 0cm 3.5pt" width="85" valign="top" |
<center>p/p<sub>o</sub><nowiki>=f(x/b),</nowiki></center>
<center>p/p<sub>o</sub>=f(x/b),</center>


<center>ζ, β<sub>2</sub></center>
<center>&zeta;, &beta;<sub>2</sub></center>
|}
|}


Table EXP-A Summary description of all test cases
 


{| style="width: 293.0pt; margin-left: 18.0pt; border-collapse: collapse" width="391"
{| style="width: 293.0pt; margin-left: 18.0pt; border-collapse: collapse" width="391"
|+ Table EXP-B Summary description of all measured parameters and available datafiles
|- style="height: 34.25pt"
|- style="height: 34.25pt"
| style="width: 44.9pt; border: solid windowtext 1.0pt; background: #F2F2F2; padding: 0cm 5.4pt 0cm 5.4pt; height: 34.25pt" width="60" valign="top" |
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EXP 1
EXP 1
| style="width: 106.35pt; border-top: none; border-left: none; border-bottom: solid windowtext 1.0pt; border-right: solid windowtext 1.0pt; padding: 0cm 5.4pt 0cm 5.4pt" width="142" |
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<center>[I/exp11.jpg exp11.jpg]</center>
<center>[[media:AC6-12_exp11.jpg|exp11.jpg]]</center>
| style="width: 5.0cm; border-top: none; border-left: none; border-bottom: solid windowtext 1.0pt; border-right: solid windowtext 1.0pt; padding: 0cm 5.4pt 0cm 5.4pt" width="189" valign="top" |
| style="width: 5.0cm; border-top: none; border-left: none; border-bottom: solid windowtext 1.0pt; border-right: solid windowtext 1.0pt; padding: 0cm 5.4pt 0cm 5.4pt" width="189" valign="top" |
<center>[http://qnetkb.cfms.org.uk/TA6/AC6-12/X/exp12.dat exp12.dat]</center>
<center>[[media:AC6-12_exp12.dat|exp12.dat]]</center>
|}
|}


Table EXP-B Summary description of all measured parameters and available datafiles<br clear="all" />
<br clear="all" />


=== References ===
=== References ===


[1]        Šafařík P. Experimental data from optical measurement tests on a transonic turbine blade cascade, Proc. of the 13<sup>th</sup> Symposium on Measuring Techniques for Transonic and Supersonic Flow in Cascades and Turbomachines (eds. C. Grossweiler, G. Gyarmathy), 20/0-20/14, ETH Zürich, 1996
[1]       &#352;afařík P. Experimental data from optical measurement tests on a transonic turbine blade cascade, Proc. of the 13<sup>th</sup> Symposium on Measuring Techniques for Transonic and Supersonic Flow in Cascades and Turbomachines (eds. C. Grossweiler, G. Gyarmathy), 20/0-20/14, ETH Zürich, 1996


[2]        Šťastný M., Šafařík P. Experimental analysis data on the transonic flow past a plane turbine cascade, ASME Paper 90-GT-313, 1990
[2]       &#352;ťastný M., &#352;afařík P. Experimental analysis data on the transonic flow past a plane turbine cascade, ASME Paper 90-GT-313, 1990


[3]        Šťastný M., Šafařík P. Boundary layer effects on the transonic flow in a straight turbine cascade, ASME Paper 92-GT-155, 1992<br clear="all" /><font size="-2" color="#888888">© copyright ERCOFTAC 2004</font><br />
[3]       &#352;ťastný M., &#352;afařík P. Boundary layer effects on the transonic flow in a straight turbine cascade, ASME Paper 92-GT-155, 1992


----
<br clear="all" />


<font size="-2" color="#888888">© copyright ERCOFTAC 2004</font><br />


Contributors: Jaromir Prihoda; Karel Kozel - Czech Academy of Sciences
----




{{AC|front=AC 6-12|description=AC 6-12 Description|testdata=AC 6-12 Test Data|cfdsimulations=AC 6-12 CFD Simulations|evaluation=AC 6-12 Evaluation|qualityreview=AC 6-12 Quality Review|bestpractice=AC 6-12 Best Practice Advice|relatedACs=AC 6-12 Related ACs}}
Contributors: Jaromir Prihoda; Karel Kozel - Czech Academy of Sciences




[[Category:Application Challenge]]
{{AC|front=AC 6-12|description=AC 6-12 Description|testdata=AC 6-12 Test Data|cfdsimulations=AC 6-12 CFD Simulations|evaluation=AC 6-12 Evaluation|qualityreview=AC 6-12 Quality Review|bestpractice=AC 6-12 Best Practice Advice|relatedUFRs=AC 6-12 Related ACs}}

Latest revision as of 18:45, 11 February 2017

Front Page

Description

Test Data

CFD Simulations

Evaluation

Best Practice Advice




Steam turbine rotor cascade

Application Challenge 6-12               © copyright ERCOFTAC 2004


Test Data

Overview of Tests

Experiments were carried out in the wind tunnel in the High-Speed Laboratory of the Institute of Thermomechanics AS CR in Prague. The blown-down wind tunnel connected to the vacuum storage (6500 m3) has a turnable test section that is 160 mm in width and 220 – 600 mm in height depending on the cascade stagger. The maximum error of inlet angle setting is 0.1 deg. The experimental facility provides the possibility of pneumatic and optical measurements in the range of Mach numbers up to M ≈ 2. The tunnel is equipped with a Mach-Zehnder interferometer (mirror Ø 156 mm) and schlieren optics, both can be used either with a nanosecond spark source or a Video system. A semi-automatic traversing device together with a digital measuring system is used to measure cascade losses as well as other aerodynamic data. The tunnel is especially suited for turbine cascades which can be measured within the range of exit Mach numbers (0.5; 2) and inlet angles β1 (30 deg; 150 deg).

The SE 1050 blade cascade was designed for the inlet flow angle β1 = 70.7 deg, the isentropic exit Mach number M2is = 1.208 and for wet steam. The flow in the blade cascade was investigated within a wide range of exit Mach numbers and inlet angles by the Mach-Zehnder interferometer.

Test data are based on interferometric pictures taken for various flow conditions. The density difference between two adjacent fringes is given by the wave length of monochromatic light and the wind tunnel width by the relation Δρ = 0.011858 kg/m3. Detailed description of the evaluation procedure is given by Šafařík (1996). The basic series 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). Measurements were carried out for following values of Mach numbers:


i(deg) M1 M2is i(deg) M1 M2is
0 0.279 0.489 0 0.376 1.007
0 0.322 0.610 0 0.376 1.099
0 0.354 0.716 0 0.375 1.198
0 0.364 0.793 0 0.379 1.313
0 0.365 0.906 0 0.377 1.387


The case corresponding to nearly design conditions with M2is=1.198 was chosen for the Application Challenge.

The measurement covers the values from low subsonic to supersonic exit velocities including the transonic region. Additional experiments were carried out for extreme values of incidence i = 70.7 -β1 covering the range from i = -67 deg (very small loading) to i = +30 deg (overloading conditions).


i (deg) M1 M2is
-67 0.545 0.905
+30 0.660 1.012



The pressure distribution on the profile surface was evaluated from interferometric pictures. Besides interferograms, measurements downstream of the cascade were carried out for various incidence i and the Mach number M2is giving exit flow angle β2 and the energy loss coefficient ζ. Measurements of exit angle and energy losses were made in the distance one chord behind the cascade. The coefficient ζ is given by the relation

A6-12d30 files image004.gif

where λ2 is the relative velocity.

Test Case EXP-1

Description of Experiment

The flow regime near the design conditions (the inlet angle β1 = 70.7 deg and the isentropic exit Mach number M2is = 1.198) was accepted to be the test case EXP1. The relevant parameters are given in the Table EXP-A.

Boundary Data

Inlet conditions are characterized by the total pressure and the total temperature upstream the cascade. The flow regime was adjusted by means of the back pressure in the settling chamber downstream the cascade. The back pressure was controlled by the throttling valve.

The profiles of the blade cascade were manufactured in high precision. The surface was smooth (glossy steel).


Measurement Errors

The dependence of Mach number errors on the value of the inlet Mach number was derived for interferometric measurements. The Mach number error can be estimated as δM = 0.005 for the Mach number M ≈ 1.

The errors of pressure and temperature were δP = 70 Pa and δT = 0.1 K. The error analysis of the data reduction method for the evaluation of the exit angle and the kinetic energy loss coefficient has not been carried out. The maximum error of the exit angle was estimated to be about 0.3 deg.

Measured Data

EXP1 Measurement of flow in the steam turbine rotor cascade: interferogram of the flow field, pressure distribution on the blade, survey of relevant parameters (given in the file exp12.dat)

The files containing results with measured and evaluated parameters are given in Table EXP-B:

exp11.jpg (interferogram with density isolines for M2is = 1.198)

exp12.dat (survey of relevant parameters β1, i, M1, M2is, Re2is, ζ, β2, p01, T01, pressure distribution on the suction and pressure sides p/p0 vers. x/b)

Table EXP-A Summary description of all test cases
Name
GNDPs
PDPs
(problem definition parameters)
MPs
(measured parameters)
Re
M2is
inlet angle
β1 (deg)
total pressure
po1 (Pa)
total temperature
To1 (K)
detailed data
ρ (kg/m3)
[../../help/glossary.htm DOAP]s
EXP 1
1.48 x 106
1.198
70.7
98071.7
298.65
ρ=f(x,y)
p/po=f(x/b),
ζ, β2


Table EXP-B Summary description of all measured parameters and available datafiles
MP1
interferogram
density isolines
MP 2
pressure distribution
p/po (1)

EXP 1

exp11.jpg
exp12.dat


References

[1] Šafařík P. Experimental data from optical measurement tests on a transonic turbine blade cascade, Proc. of the 13th Symposium on Measuring Techniques for Transonic and Supersonic Flow in Cascades and Turbomachines (eds. C. Grossweiler, G. Gyarmathy), 20/0-20/14, ETH Zürich, 1996

[2] Šťastný M., Šafařík P. Experimental analysis data on the transonic flow past a plane turbine cascade, ASME Paper 90-GT-313, 1990

[3] Šťastný M., Šafařík P. Boundary layer effects on the transonic flow in a straight turbine cascade, ASME Paper 92-GT-155, 1992


© copyright ERCOFTAC 2004



Contributors: Jaromir Prihoda; Karel Kozel - Czech Academy of Sciences


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