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{{AC|front=AC 6-02|description=Description_AC6-02|testdata=Test Data_AC6-02|cfdsimulations=CFD Simulations_AC6-02|evaluation=Evaluation_AC6-02|qualityreview=Quality Review_AC6-02|bestpractice=Best Practice Advice_AC6-02|relatedUFRs=Related UFRs_AC6-02}}
='''Low-speed centrifugal compressor'''=
='''Low-speed centrifugal compressor'''=


Line 7: Line 9:
=='''Overview of Tests'''==
=='''Overview of Tests'''==


The Low-Speed Centrifugal Compressor Facility is designed to duplicate the flow fields of a high- speed subsonic centrifugal compressor in a large low-speed machine Thus the essential flow physics of the flow field can be investigated in detail. A schematic diagram of the LSCC facility is shown in figure 4. Air is drawn into the facility room through a filtered vent in the roof and then past a bank of steam pipes and louvers designed to control the air temperature to within ± 1 oF for mass flows up to 45 kg/sec. The facility room air is then drawn into the plenum through a bank of air straighteners contained between two mesh screens. Next, the air passes through a specially designed bellmouth with a 10:1 area contraction. From there it flows into the compressor and exits through a specially designed throttle valve at the entrance to the collector. The throttle valve consists of two concentric overlapping rings with holes that have been drilled in each ring and that slide relative to each other to produce a throttle. This valve design was chosen to minimize circumferential asymmetry in the static pressure distribution at the exit, such as is typically found in scroll- type collectors. The bellmouth, inlet transition piece, and shroud flow path were machined together to minimize any boundary layer disturbance that might be caused by a step in the flow path.
The Low-Speed Centrifugal Compressor Facility is designed to duplicate the flow fields of a high- speed subsonic centrifugal compressor in a large low-speed machine Thus the essential flow physics of the flow field can be investigated in detail. A schematic diagram of the LSCC facility is shown in [[#figure 4|figure 4]]. Air is drawn into the facility room through a filtered vent in the roof and then past a bank of steam pipes and louvers designed to control the air temperature to within ± 1 oF for mass flows up to 45 kg/sec. The facility room air is then drawn into the plenum through a bank of air straighteners contained between two mesh screens. Next, the air passes through a specially designed bellmouth with a 10:1 area contraction. From there it flows into the compressor and exits through a specially designed throttle valve at the entrance to the collector. The throttle valve consists of two concentric overlapping rings with holes that have been drilled in each ring and that slide relative to each other to produce a throttle. This valve design was chosen to minimize circumferential asymmetry in the static pressure distribution at the exit, such as is typically found in scroll- type collectors. The bellmouth, inlet transition piece, and shroud flow path were machined together to minimize any boundary layer disturbance that might be caused by a step in the flow path.




Line 13: Line 15:
[[Image:Image471.jpg]]
[[Image:Image471.jpg]]
   
   
 
<span id="figure 4">
'''Figure 4.-Schematic of NASA low-speed centrifugal compressor test facility'''  
'''Figure 4.-Schematic of NASA low-speed centrifugal compressor test facility'''  
 
</span>
'''Instrumentation:'''
'''Instrumentation:'''


'''''Pneumatic probes'''''.-Spanwise probe traverses were available at stations upstream and downstream of the rotor (see figure 2). Five-hole probes with self-nulling yaw capability (figure 5) were used for all standard pneumatic probe surveys. These probes were calibrated in a steady flow duct in which the pressure and temperature could be accurately controlled. During calibration, the probe pitch angle was varied over a range of Mach numbers, and the results were used together with the five-hole probe measurements acquired in the compressor to extract total and static pressures and the pitch angle. Before a probe was installed in the compressor test rig, a check on the pitch and swirl aerodynamic zero angle was performed in a calibration jet.
'''''Pneumatic probes'''''.-Spanwise probe traverses were available at stations upstream and downstream of the rotor (see figure 2). Five-hole probes with self-nulling yaw capability [[#(figure 5)|(figure 5)]] were used for all standard pneumatic probe surveys. These probes were calibrated in a steady flow duct in which the pressure and temperature could be accurately controlled. During calibration, the probe pitch angle was varied over a range of Mach numbers, and the results were used together with the five-hole probe measurements acquired in the compressor to extract total and static pressures and the pitch angle. Before a probe was installed in the compressor test rig, a check on the pitch and swirl aerodynamic zero angle was performed in a calibration jet.


'''Surface static pressure taps'''.-Static pressure taps were provided along the shroud and rotor blade surfaces. Those on the rotor surface measured the rotor blade pressure distribution and provided the opportunity for ammonia-ozalid flow visualization. They were located along quasi-orthogonal measurement planes at nominally 5, 20, 50, 80, 93, and 97 per- cent of blade span from the hub. The quasi-orthogonal measurement planes were located at approximately 2.5, 5, 15, 30, 50, 70, 90, 95, and 98 percent of meridional distance.
'''Surface static pressure taps'''.-Static pressure taps were provided along the shroud and rotor blade surfaces. Those on the rotor surface measured the rotor blade pressure distribution and provided the opportunity for ammonia-ozalid flow visualization. They were located along quasi-orthogonal measurement planes at nominally 5, 20, 50, 80, 93, and 97 per- cent of blade span from the hub. The quasi-orthogonal measurement planes were located at approximately 2.5, 5, 15, 30, 50, 70, 90, 95, and 98 percent of meridional distance.
Line 29: Line 31:




 
<span id="(figure 5)">
'''Figure 5.-Schematic of five-hole pressure probes.'''
'''Figure 5.-Schematic of five-hole pressure probes.'''
 
</span>
    
    


Line 87: Line 89:
| || Re || Pr || M || Rotation speed (rpm) || Relative flow rate || Detailed data || [[DOAPs]]
| || Re || Pr || M || Rotation speed (rpm) || Relative flow rate || Detailed data || [[DOAPs]]
|-
|-
|'''EXP 1''' (design) || <math>1.6 10^7</math> || 0.72 || 0.45 || 1862 || 100% <math>1.6 10^7</math>|| -Blade pressure -inlet spanwise distributions -pitch-averaged exit spanwise distributions -shroud pressure distribution || Pressure ratio, <math>h_{ad}</math>
|'''EXP 1''' (design) || <math>1.6 10^7</math> || 0.72 || 0.45 || 1862 || 100% <math>m_{d}</math> || -Blade pressure -inlet spanwise distributions -pitch-averaged exit spanwise distributions -shroud pressure distribution || Pressure ratio, <math>\eta_{ad}</math>
|-
|-
|'''EXP 2''' (off-design: low flow rate) || <math>1.6 10^7</math> || 0.72 || 0.45 || 1862 || 78.7% <math>m_d</math> || -Blade pressure -inlet spanwise distributions -pitch-averaged exit spanwise distributions -shroud pressure distribution || Pressure ratio, <math>h_{ad}</math>
|'''EXP 2''' (off-design: low flow rate) || <math>1.6 10^7</math> || 0.72 || 0.45 || 1862 || 78.7% <math>m_{d}</math> || -Blade pressure -inlet spanwise distributions -pitch-averaged exit spanwise distributions -shroud pressure distribution || Pressure ratio, <math>\eta_{ad}</math>
|-
|-
|'''EXP 3''' (off-design: heigh flow rate) || <math>1.6 10^7</math> || 0.72 || 0.45 || 1862 || 133% <math>1.6 10^7</math> || -shroud pressure distribution ||  Pressure ratio, <math>h_{ad}</math>
|'''EXP 3''' (off-design: heigh flow rate) || <math>1.6 10^7</math> || 0.72 || 0.45 || 1862 || 133% <math>m_{d}</math> || -shroud pressure distribution ||  Pressure ratio, <math>\eta_{ad}</math>
|}
|}






 
<span id="table EXP-A">
Table EXP-A Summary description of all test cases
Table EXP-A Summary description of all test cases
</span>




   
{|border="1" cell padding="25" cell spacing="3"
|-
| || Blade pressure at six different spans (5%, 20%, 49%, 79%, 94%, 98%)  (PS) ||  Blade pressure at six different span (5%, 20%, 49%, 79%, 94%, 98%)  (SS) || Shroud pressure distribution || Inlet spanwise distribution || Exit spanwise distribution || [[DOAPs]]
|-
|EXP 1 || [[Media:AC6-02_exp11.dat|exp11.dat]] [[Media:AC6-02_exp12.dat|exp12.dat]] [[Media:AC6-02_exp13.dat|exp13.dat]] [[Media:AC6-02_exp14.dat|exp14.dat]] [[Media:AC6-02_exp15.dat|exp15.dat]] [[Media:AC6-02_exp16.dat|exp16.dat]] || [[Media:AC6-02_exp17.dat|exp17.dat]] [[Media:AC6-02_exp18.dat|exp18.dat]] [[Media:AC6-02_exp19.dat|exp19.dat]] [[Media:AC6-02_exp110.dat|exp110.dat]] [[Media:AC6-02_exp111.dat|exp111.dat]] [[Media:AC6-02_exp112.dat|exp112.dat]] || [[Media:AC6-02_exp113.dat|exp113.dat]] || [[Media:AC6-02_exp114.dat|exp114.dat]] || [[Media:AC6-02_exp115.dat|exp115.dat]] || [[Media:AC6-02_exp116.dat|exp116.dat]]
|-
|EXP 2 || [[Media:AC6-02_exp21.dat|exp21.dat]] [[Media:AC6-02_exp22.dat|exp22.dat]] [[Media:AC6-02_exp23.dat|exp23.dat]] [[Media:AC6-02_exp24.dat|exp24.dat]] [[Media:AC6-02_exp25.dat|exp25.dat]] [[Media:AC6-02_exp26.dat|exp26.dat]] || [[Media:AC6-02_exp27.dat|exp27.dat]] [[Media:AC6-02_exp28.dat|exp28.dat]] [[Media:AC6-02_exp29.dat|exp29.dat]] [[Media:AC6-02_exp210.dat|exp210.dat]] [[Media:AC6-02_exp211.dat|exp211.dat]] [[Media:AC6-02_exp212.dat|exp212.dat]] || [[Media:AC6-02_exp213.dat|exp213.dat]] || [[Media:AC6-02_exp214.dat|exp214.dat]] || [[Media:AC6-02_exp215.dat|exp215.dat]] || [[Media:AC6-02_exp216.dat|exp216.dat]]
|-
|EXP 3 || No Data || No Data || [[Media:AC6-02_exp31.dat|exp31.dat]] || No Data || No Data || [[Media:AC6-02_exp32.dat|exp32.dat]]
|}


Blade pressure at six different span


(5%, 20%, 49%, 79%, 94%, 98% )
Table EXP-B Summary description of all measured parameters and available datafiles


(PS)
=='''Test Case EXP-1'''==


Blade pressure at six different span


(5%, 20%, 49%, 79%, 94% , 98% )
'''Description of Experiment'''


(SS)
For this experimental setup, the design conditions were selected. The GNDPs and the


Shroud pressure distribution
PDPs are summarized in [[#table EXP-A|table EXP-A]].


Inlet


spanwise
'''Boundary Data'''


distribution
Spanwise distribution of absolute total pressure, absolute flow angle and pitch angle are given by experiments at impeller inlet station 1 [[#(see Figure 2)|(see Figure 2)]].


Exit spanwise
These data are provided in the file [[Media:AC6-02_exp114.dat|exp114.dat]]


distribution
Spanwise distribution of absolute total pressure, static pressure, absolute total temperature, absolute flow angle and pitch angle are given by experiments at impeller exit station 2 [[#(see Figure 2)|(see Figure 2)]].


DOAPs
These data are provided in the file [[Media:AC6-02_exp115.dat|exp115.dat]]


EXP 1
No experimental data is provided for the turbulent Reynolds stresses so that assumptions have to be made for the derivation of the turbulent kinetic energy and the turbulent dissipation. The solid walls are assumed smooth.


exp11.dat


exp12.dat
'''Measurement Errors'''


exp13.dat
The errors in measurement quantities for all tests are:


exp14.dat


exp15.dat
'''Aerodynamic probe measurements:'''


exp16.dat
Flow angle : a = ±1.5degrees


exp17.dat
Static and Total pressure : P,p = ± 68,95 Pa (or 0.07%)


exp18.dat
Static temperature : T= ± 0.6 K (or 0.19%)


exp19.dat
Mass flow rate : Mf=± 0.091 kg/s (or 0.3%)


exp110.dat
The uncertainties are a best estimate based on precision, bias, and measurement repeatability. The Nonrepeatability is the greatest contributor to the uncertainties.


exp111.dat


exp112.dat
'''Laser anemometer measurements:'''


exp113.dat
Velocity components :u,v,w=±1.5 m/s (or 2%)


The main contribution to the uncertainties comes from the window curvature. In the rear of the impeller where the window curvature and the blade span both decrease, the error is less than 2%.




exp114.dat
'''Measured Data'''


The format of the available data files is described next


'''EXP1 :''' Experimental setup at design conditions:


exp115.dat
[[Media:AC6-02_exp11.dat|exp11.dat]]  to [[Media:AC6-02_exp16.dat|exp16.dat]]
(ASCII file; headers: Blade pressure distribution on pressure side at 5%, 20%, 49%, 79%, 94%
and 98% span from hub; columns: z, r, &lt;p/p<sub>std</sub>&gt;)


exp116.dat
[[Media:AC6-02_exp17.dat|exp17.dat]] to [[Media:AC6-02_exp112.dat|exp112.dat]]
(ASCII file; headers: Blade pressure distribution on suction side at 5%, 20%, 49%, 79%, 94%
and 98% span from hub; columns: z, r, &lt;p/p<sub>std</sub>&gt;)


EXP 2
[[Media:AC6-02_exp113.dat|exp113.dat]] (ASCII file, headers: Shroud pressure distribution
columns: z, r, &lt;p/p<sub>std</sub>&gt;)


exp21.dat
[[Media:AC6-02_exp114.dat|exp114.dat]] (ASCII file, headers: Inlet spanwise distributions :station 1
columns: r, &lt;P/p<sub>std</sub>&gt;, &lt;p/p<sub>std</sub>&gt;), <absolute flow angle(deg) >, <pitch angle(deg) >)


exp22.dat
[[Media:AC6-02_exp115.dat|exp115.dat]] (ASCII file, headers: Outlet spanwise distributions :station 2
columns: z, &lt;P/p<sub>std</sub>&gt;, &lt;T/t<sub>std</sub>&gt;),
&lt;p/p<sub>std</sub>&gt;), &lt;absolute flow angle(deg) &gt;, &lt;pitch angle(deg) &gt;)


exp23.dat
[[DOAPs]]:
[[Media:AC6-02_exp116.dat|exp116.dat]] (ASCII file, headers: Pressure ratio and adiabatic efficiency
Pressure ratio, h<sub>ad</sub>)


exp24.dat
=='''References'''==


exp25.dat
Hathaway, M. D., Chriss R. M., Strazisar, A. J., and Wood, J. R., 1995, "Laser Anemometer Measurements of the Three-Dimensional Rotor Flow Field in the NASA Low-Speed Centrifugal Compressor: NASA Technical Paper, ARL-TR-333.
 
exp26.dat
 
exp27.dat
 
exp28.dat
 
exp29.dat
 
exp210.dat
 
exp211.dat
 
exp212.dat
 
exp213.dat
 
 
 
exp214.dat
 
 
 
exp215.dat
 
exp216.dat
 
EXP 3
 
No data
 
No data
 
exp31.dat


No data


No data
=='''Test Case EXP-2'''==


exp32.dat


'''Description of Experiment'''


Table EXP-B Summary description of all measured parameters and available datafiles
For this experimental setup, the off-design conditions were selected (low flow rate). The GNDPs and the PDPs are summarized in [[#table EXP-A|table EXP-A]].
© ERCOFTAC 2004
Test Case EXP-1
© ERCOFTAC 2004
Description of Experiment


For this experimental setup, the design conditions were selected. The GNDPs and the


PDPs are summarized in table EXP-A.
'''Boundary Data'''
© ERCOFTAC 2004
Boundary Data


Spanwise distribution of absolute total pressure, absolute flow angle and pitch angle are given by experiments at impeller inlet station 1 (see Figure 2).
Spanwise distribution of absolute total pressure, static pressure, absolute flow angle and pitch angle are given by experiments at impeller inlet station 1 [[#(see Figure 2)|(see Figure 2)]].


These data are provided in the file exp114.dat
These data are provided in the file [[Media:AC6-02_exp214.dat|exp214.dat]]


Spanwise distribution of absolute total pressure, static pressure, absolute total temperature, absolute flow angle and pitch angle are given by experiments at impeller exit station 2 (see Figure 2).
Spanwise distribution of absolute total pressure, static pressure, absolute total temperature, absolute flow angle and pitch angle are given by experiments at impeller exit station 2 [[#(see Figure 2)|(see Figure 2)]].


These data are provided in the file exp115.dat
These data are provided in the file [[Media:AC6-02_exp215.dat|exp215.dat]]


No experimental data is provided for the turbulent Reynolds stresses so that assumptions have to be made for the derivation of the turbulent kinetic energy and the turbulent dissipation. The solid walls are assumed smooth.
No experimental data is provided for the turbulent Reynolds stresses so that assumptions have to be made for the derivation of the turbulent kinetic energy and the turbulent dissipation. The solid walls are assumed smooth.
© ERCOFTAC 2004
Measurement Errors


The errors in measurement quantities for all tests are:


Aerodynamic probe measurements:
'''Measurement Errors'''


Flow angle : a = ±1.5degrees
The same as for EXP1
 
Static and Total pressure : P,p = ± 68,95 Pa (or 0.07%)
 
Static temperature : T= ± 0.6 K (or 0.19%)
 
Mass flow rate : Mf=± 0.091 kg/s (or 0.3%)
 
The uncertainties are a best estimate based on precision, bias, and measurement repeatability. The Nonrepeatability is the greatest contributor to the uncertainties.
 
Laser anemometer measurements:


Velocity components :u,v,w=±1.5 m/s (or 2%)


The main contribution to the uncertainties comes from the window curvature. In the rear of the impeller where the window curvature and the blade span both decrease, the error is less than 2%.
'''Measured Data'''
© ERCOFTAC 2004
Measured Data


The format of the available data files is described next
The format of the available data files is described next


EXP1 : Experimental setup at design conditions:
'''EXP2 :''' Experimental setup at Off-design conditions:


exp11.dat to exp16.dat
[[Media:AC6-02_exp21.dat|exp21.dat]] to [[Media:AC6-02_exp26.dat|exp26.dat]] (ASCII file; headers: Blade pressure distribution on pressure side at 5%, 20%, 49%, 79%, 94% and 98% span from hub; columns: z, r, &lt;p/pstd&gt;)


(ASCII file; headers: Blade pressure distribution on pressure side at 5%, 20%, 49%, 79%, 94% and 98% span from hub;
[[Media:AC6-02_exp27.dat|exp27.dat]] to [[Media:AC6-02_exp212.dat|exp212.dat]] (ASCII file; headers: Blade pressure distribution on suction side at 5%, 20%, 49%, 79%, 94% and 98% span from hub; columns: z, r, &lt;p/pstd&gt;)


columns: z, r, <p/pstd>)
[[Media:AC6-02_exp213.dat|exp213.dat]] (ASCII file, headers: Shroud pressure distribution columns: z, r, &lt;p/pstd&gt;)


exp17.dat to exp112.dat
[[Media:AC6-02_exp214.dat|exp214.dat]] (ASCII file, headers: Inlet spanwise distributions :station 1 columns: r, &lt;P/pstd&gt;, &lt;p/pstd&gt;), &lt;absolute flow angle(deg)&gt;, &lt;pitch angle(deg)&gt;)


(ASCII file; headers: Blade pressure distribution on suction side at 5%, 20%, 49%, 79%, 94% and 98% span from hub;
[[Media:AC6-02_exp215.dat|exp215.dat]] (ASCII file, headers: Outlet spanwise distributions :station 2 columns: z, &lt;P/pstd&gt;, &lt;T/tstd&gt;), &lt;p/pstd&gt;), &lt;absolute flow angle(deg)&gt;, &lt;pitch angle(deg)&gt;)


columns: z, r, <p/pstd>)
[[DOAPs]]:


exp113.dat (ASCII file, headers: Shroud pressure distribution
[[Media:AC6-02_exp216.dat|exp216.dat]] (ASCII file, headers: Pressure ratio and adiabatic efficiency Pressure ratio, h<sub>ad</sub>)


columns: z, r, <p/pstd>)
=='''References'''==


exp114.dat (ASCII file, headers: Inlet spanwise distributions :station 1
Hathaway, M. D., Chriss R. M., Strazisar, A. J., and Wood, J. R., 1995, "Laser Anemometer Measurements of the Three-Dimensional Rotor Flow Field in the NASA Low-Speed Centrifugal Compressor: NASA Technical Paper, ARL-TR-333.


columns: r, <P/pstd>, <p/pstd>), <absolute flow angle(deg) >, <pitch angle(deg) >)


exp115.dat (ASCII file, headers: Outlet spanwise distributions :station 2
=='''Test Case EXP-3'''==


columns: z, <P/pstd>, <T/tstd>), <p/pstd>), <absolute flow angle(deg) >, <pitch angle(deg) >)


DOAPs:
'''Description of Experiment'''


exp116.dat (ASCII file, headers: Pressure ratio and adiabatic efficiency
For this experimental setup, the off-design conditions were selected (high flow rate). The GNDPs and the PDPs are summarized in [[#table EXP-A|table EXP-A]].


Pressure ratio, had
© ERCOFTAC 2004
References


Hathaway, M. D., Chriss R. M., Strazisar, A. J., and Wood, J. R., 1995, "Laser Anemometer Measurements of the Three-Dimensional Rotor Flow Field in the NASA Low-Speed Centrifugal Compressor: NASA Technical Paper, ARL-TR-333.
'''Boundary Data'''
© ERCOFTAC 2004
Test Case EXP-2
© ERCOFTAC 2004
Description of Experiment


For this experimental setup, the off-design conditions were selected (low flow rate). The GNDPs and the PDPs are summarized in table EXP-A.
No experimental data is provided at boundaries
© ERCOFTAC 2004
Boundary Data


Spanwise distribution of absolute total pressure, static pressure, absolute flow angle and pitch angle are given by experiments at impeller inlet station 1 (see Figure 2).


These data are provided in the file exp214.dat
'''Measurement Errors'''


Spanwise distribution of absolute total pressure, static pressure, absolute total temperature, absolute flow angle and pitch angle are given by experiments at impeller exit station 2 (see Figure 2).
The same as for EXP1
 
These data are provided in the file exp215.dat


No experimental data is provided for the turbulent Reynolds stresses so that assumptions have to be made for the derivation of the turbulent kinetic energy and the turbulent dissipation. The solid walls are assumed smooth.
© ERCOFTAC 2004
Measurement Errors


The same as for EXP1
'''Measured Data'''
© ERCOFTAC 2004
Measured Data


The format of the available data files is described next
The format of the available data files is described next


EXP2 : Experimental setup at Off-design conditions:
'''EXP3 :''' Experimental setup at Off-design conditions (high flow rate):
 
exp21.dat to exp26.dat
 
(ASCII file; headers: Blade pressure distribution on pressure side at 5%, 20%, 49%, 79%, 94% and 98% span from hub;
 
columns: z, r, <p/pstd>)
 
exp27.dat to exp212.dat
 
(ASCII file; headers: Blade pressure distribution on suction side at 5%, 20%, 49%, 79%, 94% and 98% span from hub;
 
columns: z, r, <p/pstd>)
 
exp213.dat (ASCII file, headers: Shroud pressure distribution
 
columns: z, r, <p/pstd>)


exp214.dat (ASCII file, headers: Inlet spanwise distributions :station 1
[[Media:AC6-02_exp31.dat|exp31.dat]] (ASCII file, headers: Shroud pressure distribution columns: z, r, &lt;p/pstd&gt;)


columns: r, <P/pstd>, <p/pstd>), <absolute flow angle(deg) >, <pitch angle(deg) >)
[[DOAPs]]:


exp215.dat (ASCII file, headers: Outlet spanwise distributions :station 2
[[Media:AC6-02_exp32.dat|exp32.dat]] (ASCII file, headers: Pressure ratio and adiabatic efficiency Pressure ratio, <math>\eta_{ad}</math>


columns: z, <P/pstd>, <T/tstd>), <p/pstd>), <absolute flow angle(deg) >, <pitch angle(deg) >)
=='''References'''==
 
DOAPs:
 
exp216.dat (ASCII file, headers: Pressure ratio and adiabatic efficiency
 
Pressure ratio, had
© ERCOFTAC 2004
References


Hathaway, M. D., Chriss R. M., Strazisar, A. J., and Wood, J. R., 1995, "Laser Anemometer Measurements of the Three-Dimensional Rotor Flow Field in the NASA Low-Speed Centrifugal Compressor: NASA Technical Paper, ARL-TR-333.
Hathaway, M. D., Chriss R. M., Strazisar, A. J., and Wood, J. R., 1995, "Laser Anemometer Measurements of the Three-Dimensional Rotor Flow Field in the NASA Low-Speed Centrifugal Compressor: NASA Technical Paper, ARL-TR-333.
© ERCOFTAC 2004
Test Case EXP-3
© ERCOFTAC 2004
Description of Experiment


For this experimental setup, the off-design conditions were selected (high flow rate). The GNDPs and the PDPs are summarized in table EXP-A.
© ERCOFTAC 2004
Boundary Data


No experimental data is provided at boundaries
© ERCOFTAC 2004
Measurement Errors


The same as for EXP1
© copyright ERCOFTAC 2004
© ERCOFTAC 2004
Measured Data
 
The format of the available data files is described next


EXP3 : Experimental setup at Off-design conditions (high flow rate):
----
 
exp31.dat (ASCII file, headers: Shroud pressure distribution
 
columns: z, r, <p/pstd>)
 
DOAPs:
 
exp32.dat (ASCII file, headers: Pressure ratio and adiabatic efficiency
 
Pressure ratio, had
© ERCOFTAC 2004
References
 
Hathaway, M. D., Chriss R. M., Strazisar, A. J., and Wood, J. R., 1995, "Laser Anemometer Measurements of the Three-Dimensional Rotor Flow Field in the NASA Low-Speed Centrifugal Compressor: NASA Technical Paper, ARL-TR-333.
© copyright ERCOFTAC 2004


Contributors: Nouredine Hakimi - NUMECA International
Contributors: Nouredine Hakimi - NUMECA International


Site Design and Implementation: Atkins and UniS
Site Design and Implementation: [[Atkins]] and [[UniS]]
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{{AC|front=AC 6-02|description=Description_AC6-02|testdata=Test Data_AC6-02|cfdsimulations=CFD Simulations_AC6-02|evaluation=Evaluation_AC6-02|qualityreview=Quality Review_AC6-02|bestpractice=Best Practice Advice_AC6-02|relatedUFRs=Related UFRs_AC6-02}}

Latest revision as of 16:54, 11 February 2017

Front Page

Description

Test Data

CFD Simulations

Evaluation

Best Practice Advice

Low-speed centrifugal compressor

Application Challenge 6-02 © copyright ERCOFTAC 2004


Overview of Tests

The Low-Speed Centrifugal Compressor Facility is designed to duplicate the flow fields of a high- speed subsonic centrifugal compressor in a large low-speed machine Thus the essential flow physics of the flow field can be investigated in detail. A schematic diagram of the LSCC facility is shown in figure 4. Air is drawn into the facility room through a filtered vent in the roof and then past a bank of steam pipes and louvers designed to control the air temperature to within ± 1 oF for mass flows up to 45 kg/sec. The facility room air is then drawn into the plenum through a bank of air straighteners contained between two mesh screens. Next, the air passes through a specially designed bellmouth with a 10:1 area contraction. From there it flows into the compressor and exits through a specially designed throttle valve at the entrance to the collector. The throttle valve consists of two concentric overlapping rings with holes that have been drilled in each ring and that slide relative to each other to produce a throttle. This valve design was chosen to minimize circumferential asymmetry in the static pressure distribution at the exit, such as is typically found in scroll- type collectors. The bellmouth, inlet transition piece, and shroud flow path were machined together to minimize any boundary layer disturbance that might be caused by a step in the flow path.


Image471.jpg

Figure 4.-Schematic of NASA low-speed centrifugal compressor test facility Instrumentation:

Pneumatic probes.-Spanwise probe traverses were available at stations upstream and downstream of the rotor (see figure 2). Five-hole probes with self-nulling yaw capability (figure 5) were used for all standard pneumatic probe surveys. These probes were calibrated in a steady flow duct in which the pressure and temperature could be accurately controlled. During calibration, the probe pitch angle was varied over a range of Mach numbers, and the results were used together with the five-hole probe measurements acquired in the compressor to extract total and static pressures and the pitch angle. Before a probe was installed in the compressor test rig, a check on the pitch and swirl aerodynamic zero angle was performed in a calibration jet.

Surface static pressure taps.-Static pressure taps were provided along the shroud and rotor blade surfaces. Those on the rotor surface measured the rotor blade pressure distribution and provided the opportunity for ammonia-ozalid flow visualization. They were located along quasi-orthogonal measurement planes at nominally 5, 20, 50, 80, 93, and 97 per- cent of blade span from the hub. The quasi-orthogonal measurement planes were located at approximately 2.5, 5, 15, 30, 50, 70, 90, 95, and 98 percent of meridional distance.

Laser anemometer system.- The laser anemometer system used for the present investigation was a two-component laser fringe anemometer operating in on-axis backscatter mode. Optical access to the flow field was provided by three 3-mm-thick glass windows that conformed to the flow path in both the circumferential and stream wise directions. The windows covered the inlet, knee, and exit regions of the impeller and the inlet of the vaneless diffuser. Polystyrene latex (PSL) spheres, used as seed particles, were introduced into the flow stream via four spray nozzles located in the plenum. During the development of the seeding system, an aerodynamic particle sizer was used to ensure that the seeding system could deliver mono-disperse particles and that the liquid carrier was fully evaporated by the time the seed.


Image419.gif


Figure 5.-Schematic of five-hole pressure probes.


For Design and off-design conditions (78,7 % of design mass flow), available experimental data are listed below:

• Spanwise distribution of Pitch averaged total pressure, static pressure, total temperature, absolute flow angle, pitch angle measured from Axial at impeller exit survey station 2

• Spanwise distribution of Pitch averaged total pressure, static pressure, absolute flow angle, pitch angle measured from Axial at impeller inlet survey station 1

• Normalized shroud pitch averaged static pressure distribution

• Normalized blade static pressure distribution at 5%, 20%, 49%, 79%, 94% and 98% span from hub

• Radial velocity component, axial velocity component and relative tangential velocity normalized by tip speed at different meridional stations (From laser measurements)

• Impeller total pressure ratio

• Impeller adiabatic efficiency


Data available only at design condition:

• Pitch angle measured from axial at 5%, 20%, 49%, 79%, 94% and 98% span from hub (From laser measurements)


Data available for a range of mass flows:

• Normalized shroud pitch averaged static pressure distribution

• Impeller total pressure ratio

• Impeller adiabatic efficiency

The complete data are provided in the reference paper and will not all be provided for the application challenge.


The problem definition parameters (PDPs) are

• Rotation speed: 1862 rpm

• Relative flow rate

o 133-percent md (39.9 kg/s)

o 100-percent md (md=30kg/s (design condition))

o 78.7-percent md (23.6 kg/s)



NAME GNDPs PDPs (problem definition parameters) MPs (measured parameters)
Re Pr M Rotation speed (rpm) Relative flow rate Detailed data DOAPs
EXP 1 (design) 0.72 0.45 1862 100% -Blade pressure -inlet spanwise distributions -pitch-averaged exit spanwise distributions -shroud pressure distribution Pressure ratio,
EXP 2 (off-design: low flow rate) 0.72 0.45 1862 78.7% -Blade pressure -inlet spanwise distributions -pitch-averaged exit spanwise distributions -shroud pressure distribution Pressure ratio,
EXP 3 (off-design: heigh flow rate) 0.72 0.45 1862 133% -shroud pressure distribution Pressure ratio,


Table EXP-A Summary description of all test cases


Blade pressure at six different spans (5%, 20%, 49%, 79%, 94%, 98%) (PS) Blade pressure at six different span (5%, 20%, 49%, 79%, 94%, 98%) (SS) Shroud pressure distribution Inlet spanwise distribution Exit spanwise distribution DOAPs
EXP 1 exp11.dat exp12.dat exp13.dat exp14.dat exp15.dat exp16.dat exp17.dat exp18.dat exp19.dat exp110.dat exp111.dat exp112.dat exp113.dat exp114.dat exp115.dat exp116.dat
EXP 2 exp21.dat exp22.dat exp23.dat exp24.dat exp25.dat exp26.dat exp27.dat exp28.dat exp29.dat exp210.dat exp211.dat exp212.dat exp213.dat exp214.dat exp215.dat exp216.dat
EXP 3 No Data No Data exp31.dat No Data No Data exp32.dat


Table EXP-B Summary description of all measured parameters and available datafiles

Test Case EXP-1

Description of Experiment

For this experimental setup, the design conditions were selected. The GNDPs and the

PDPs are summarized in table EXP-A.


Boundary Data

Spanwise distribution of absolute total pressure, absolute flow angle and pitch angle are given by experiments at impeller inlet station 1 (see Figure 2).

These data are provided in the file exp114.dat

Spanwise distribution of absolute total pressure, static pressure, absolute total temperature, absolute flow angle and pitch angle are given by experiments at impeller exit station 2 (see Figure 2).

These data are provided in the file exp115.dat

No experimental data is provided for the turbulent Reynolds stresses so that assumptions have to be made for the derivation of the turbulent kinetic energy and the turbulent dissipation. The solid walls are assumed smooth.


Measurement Errors

The errors in measurement quantities for all tests are:


Aerodynamic probe measurements:

Flow angle : a = ±1.5degrees

Static and Total pressure : P,p = ± 68,95 Pa (or 0.07%)

Static temperature : T= ± 0.6 K (or 0.19%)

Mass flow rate : Mf=± 0.091 kg/s (or 0.3%)

The uncertainties are a best estimate based on precision, bias, and measurement repeatability. The Nonrepeatability is the greatest contributor to the uncertainties.


Laser anemometer measurements:

Velocity components :u,v,w=±1.5 m/s (or 2%)

The main contribution to the uncertainties comes from the window curvature. In the rear of the impeller where the window curvature and the blade span both decrease, the error is less than 2%.


Measured Data

The format of the available data files is described next

EXP1 : Experimental setup at design conditions:

exp11.dat to exp16.dat (ASCII file; headers: Blade pressure distribution on pressure side at 5%, 20%, 49%, 79%, 94% and 98% span from hub; columns: z, r, <p/pstd>)

exp17.dat to exp112.dat (ASCII file; headers: Blade pressure distribution on suction side at 5%, 20%, 49%, 79%, 94% and 98% span from hub; columns: z, r, <p/pstd>)

exp113.dat (ASCII file, headers: Shroud pressure distribution columns: z, r, <p/pstd>)

exp114.dat (ASCII file, headers: Inlet spanwise distributions :station 1 columns: r, <P/pstd>, <p/pstd>), <absolute flow angle(deg) >, <pitch angle(deg) >)

exp115.dat (ASCII file, headers: Outlet spanwise distributions :station 2 columns: z, <P/pstd>, <T/tstd>), <p/pstd>), <absolute flow angle(deg) >, <pitch angle(deg) >)

DOAPs: exp116.dat (ASCII file, headers: Pressure ratio and adiabatic efficiency Pressure ratio, had)

References

Hathaway, M. D., Chriss R. M., Strazisar, A. J., and Wood, J. R., 1995, "Laser Anemometer Measurements of the Three-Dimensional Rotor Flow Field in the NASA Low-Speed Centrifugal Compressor: NASA Technical Paper, ARL-TR-333.


Test Case EXP-2

Description of Experiment

For this experimental setup, the off-design conditions were selected (low flow rate). The GNDPs and the PDPs are summarized in table EXP-A.


Boundary Data

Spanwise distribution of absolute total pressure, static pressure, absolute flow angle and pitch angle are given by experiments at impeller inlet station 1 (see Figure 2).

These data are provided in the file exp214.dat

Spanwise distribution of absolute total pressure, static pressure, absolute total temperature, absolute flow angle and pitch angle are given by experiments at impeller exit station 2 (see Figure 2).

These data are provided in the file exp215.dat

No experimental data is provided for the turbulent Reynolds stresses so that assumptions have to be made for the derivation of the turbulent kinetic energy and the turbulent dissipation. The solid walls are assumed smooth.


Measurement Errors

The same as for EXP1


Measured Data

The format of the available data files is described next

EXP2 : Experimental setup at Off-design conditions:

exp21.dat to exp26.dat (ASCII file; headers: Blade pressure distribution on pressure side at 5%, 20%, 49%, 79%, 94% and 98% span from hub; columns: z, r, <p/pstd>)

exp27.dat to exp212.dat (ASCII file; headers: Blade pressure distribution on suction side at 5%, 20%, 49%, 79%, 94% and 98% span from hub; columns: z, r, <p/pstd>)

exp213.dat (ASCII file, headers: Shroud pressure distribution columns: z, r, <p/pstd>)

exp214.dat (ASCII file, headers: Inlet spanwise distributions :station 1 columns: r, <P/pstd>, <p/pstd>), <absolute flow angle(deg)>, <pitch angle(deg)>)

exp215.dat (ASCII file, headers: Outlet spanwise distributions :station 2 columns: z, <P/pstd>, <T/tstd>), <p/pstd>), <absolute flow angle(deg)>, <pitch angle(deg)>)

DOAPs:

exp216.dat (ASCII file, headers: Pressure ratio and adiabatic efficiency Pressure ratio, had)

References

Hathaway, M. D., Chriss R. M., Strazisar, A. J., and Wood, J. R., 1995, "Laser Anemometer Measurements of the Three-Dimensional Rotor Flow Field in the NASA Low-Speed Centrifugal Compressor: NASA Technical Paper, ARL-TR-333.


Test Case EXP-3

Description of Experiment

For this experimental setup, the off-design conditions were selected (high flow rate). The GNDPs and the PDPs are summarized in table EXP-A.


Boundary Data

No experimental data is provided at boundaries


Measurement Errors

The same as for EXP1


Measured Data

The format of the available data files is described next

EXP3 : Experimental setup at Off-design conditions (high flow rate):

exp31.dat (ASCII file, headers: Shroud pressure distribution columns: z, r, <p/pstd>)

DOAPs:

exp32.dat (ASCII file, headers: Pressure ratio and adiabatic efficiency Pressure ratio,

References

Hathaway, M. D., Chriss R. M., Strazisar, A. J., and Wood, J. R., 1995, "Laser Anemometer Measurements of the Three-Dimensional Rotor Flow Field in the NASA Low-Speed Centrifugal Compressor: NASA Technical Paper, ARL-TR-333.


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