Mean flow and turbulence data
from the
Princeton University Gasdynamics Lab
Low-speed wind tunnel 








Randall W. Smith and Alexander J. Smits


                            Gasdynamics Lab


          Department of Mechanical and Aerospace Engineering


                         Princeton University


                 Princeton, New Jersey 08544-0710  USA










Current addresses:








Randall W. Smith 
Alexander J. Smits 




 Environmental Sciences Group (EVG) 

Applied Research Laboratories

Austin, Texas 78713-8029  USA		
 Gasdynamics Lab

James Forrestal Campus

Princeton University

Princeton, New Jersey 08544-0710  USA		




 phone: (512)835-3768 (work) 

(512)835-3259 (FAX) 		
 phone: (609)258-5117 (work) 

(609)258-2282 (FAX) 		




 E-mail:   smithr@arlut.utexas.edu
 E-mail:  asmits@pucc.princeton.edu











Data Files




In directory "MEAN":





Each of these files contains the results of a Pitot tube survey.  There is a 9 line header in each file containing information about the  flow conditions, followed by two columns of data: the first column is the distance from the wall (y) in mm; the second column is the ratio of the local mean velocity to the freestream velocity.

In the file names, the number xxxx is the local momentum thickness Reynolds number, and "UMN" stands for the mean value of the streamwise velocity component (U).





In directory "TURB":






For these files, the xxxx.UMN files contain Pitot survey results, and are in the same format, and use the same naming convention, as the files in directory "MEAN".

The xxxx.U files contain results for hot-wire surveys using a single normal-wire probe, where "xxxx" is the local momentum thickness Reynolds number.  The files contain a 9 line header of general  information, followed by 6 columns of data:

    

  1.  a point index, varying from 1 (or 2) to the number of points in the survey.

  2.  the distance from the wall (y) in meters.

  3.  the mean value of the streamwise velocity component (U) in m/s .

  4.  the mean-sqaured-value of the fluctuating streamwise velocity component, u'^2, in m^2/s^2.

  5.  the mean value of the third moment, u'^3, of u' in m^3/s^3.

  6.  the mean value of the fourth moment, u'^4, of u'in m^4/s^4.



The xxxx.UV files contain results for hot-wire surveys using a single crossed-wire probe oriented so as to measure u' and v' simultaneously (u' is the fluctuating component of the streamwise velocity, and v' is the fluctuating component of the wall-normal velocity).  The files contain a 9 line header, followed by 12 columns of data:

    

  1.  a point index, varying from 1 (or 2) to the number of points in the survey.

  2.  the distance from the wall (y) in meters.

  3.   the mean value of the streamwise velocity component (U) in m/s.

  4.   the mean value of the wall-normal velocity component (V) in m/s.

  5.   the mean-squared-value of the fluctuating streamwise velocity component, u'^2, in m^2/s^2.

  6.   the mean value of the product u'v' (the Reynolds shear stress) in m^2/s^2.

  7.   the mean-squared-value of the fluctuating wall-normal velocity component, v'^2, in m^2/s^2.

  8.   the mean value of u'^3 in m^3/s^3.

  9.   the mean value of u'^2*v' in m^3/s^3.

  10.   the mean value of u'*v'^2 in m^3/s^3.

  11.   the mean value of v'^3 in m^3/s^3.

  12.   the mean value of u'^4 in m^4/s^4.




The xxxx.UW files contain results of hot-wire surveys using a single crossed-wire probe oriented so as to measure u' and w' simultaneously  (u' is the fluctuating component of the streamwise velocity, and w' is the fluctuating component of the spanwise velocity).  The files use the same naming convention, and have the same format, as the xxxx.UV files, however w' replaces v'.





 NOTES




    


  • All of the turbulence statistics are given in dimensional quantities -- the data have NOT been normalized by the friction velocity.  The appropriate friction velocities and freestream velocities are given in the header of each file.  Appendix B in R. W. Smith's Ph.D. Dissertation ("Effect of Reynolds Number on the Structure of Turbulent Boundary Layers", Princeton University, Department of Mechanical and Aerospace Engineering, Report 1984-T, 1994) outlines the method used to determine these values of the friction velocity.
    



  • In the Pitot survey files (xxxx.UMN) the value of the skin friction coefficient and friction velocity, given in the file headers, were determined from the Clauser chart method (using kappa=0.41 and C=5.2 in the log-law expressed in inner variables).
    



  • The data in directory "MEAN" should be treated separately from the data in directory "TURB".  The two sets of data were taken at separate times, and the overall flow conditions in the wind tunnel changed slightly between the acquisition of the two sets of data.
    




For further details of data acquisition and analysis procedures, see R. W. Smith's dissertation.