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Title:  Fluctuating VelocityPressure Field Structure in a Round Jet Turbulent Mixing Region 
Author(s):  Nithianandan, C.K. 
Department / Program:  Nuclear Engineering 
Discipline:  Nuclear Engineering 
Degree Granting Institution:  University of Illinois at UrbanaChampaign 
Degree:  Ph.D. 
Genre:  Dissertation 
Subject(s):  Engineering, Nuclear
Energy 
Abstract:  An experimental study of turbulent mixing has been conducted to provide detailed insight regarding the turbulent transport processes, especially those involving pressure. The investigation was conducted in the mixing region of a 6.35 cm diameter, isothermal, stationary jet having an exit velocity of 91.4 m/s. The study involved the following related parts: (1) measurements of singlepoint pressurevelocity correlations and estimation of the error involved in these correlations due to the velocity contamination of the pressure probe; (2) measurements of the three velocity components simultaneously, in order to obtain higher order velocity correlations and to verify the similarity of these correlations so that similarity assumptions can be used in the turbulent kinetic energy balance and in turbulent modeling work; (3) estimation of twodimensional velocity vector patterns representing the largescale coherent structures from the pressurevelocity correlation measurements using the linear estimation theory; (4) review and experimental verification of velocity and pressure spectra modeling theory based on dimensional analysis and extension of this study to include cross spectra of shear stress and pressurevelocity correlations; and (5) verification of the turbulent kinetic energy balance. Multichannel hot wire anemometry techniques were used to study the turbulent characteristics of the velocity field. Both Xprobes and a special 3wire sensor probe were used in conjunction with a bleed type pressure transducer to obtain the velocity components and the pressure fluctuations simultaneously. The XprobePT (= pressure transducer) data were analyzed, assuming low intensity turbulence, using both analog and digital signal processing. The 3wirePT data were analogtodigital converted and digitally analyzed on an IBM 360 computer using the analytical response equations for inclined hotwires accurate to thirdorder velocity correlation terms. All of the correlations in the driven mixing region are found to be self similar. This observation helped considerably in obtaining the turbulent kinetic energy balance and in representing other aspects of the turbulent field, such as low wavenumber spectral similarity. The experimental verification of the turbulent kinetic energy balance is found to be satisfactory, and the mean error across the mixing region is about 5% of the sum of the absolute values of the terms in the kinetic energy equation. From these results, it is estimated that the error in the measured pressurevelocity correlation is about 9%. The single component spectra of pressure and velocity are found to agree well with the results obtained using dimensional analysis. The dimensional analysis approach is extended to the cross spectra of shear stress and pressurevelocity correlations. The measured results are found to agree well with the theoretical results. In the inertial subrange, the magnitude of the pressureradial velocity spectra, along the centerline of mixing at four and five diamenters from the exit of the jet are found to agree well with the exact pressurevelocity spectra from theory. 
Issue Date:  1980 
Type:  Text 
Language:  English 
Description:  258 p. Thesis (Ph.D.)University of Illinois at UrbanaChampaign, 1980. 
URI:  http://hdl.handle.net/2142/67791 
Other Identifier(s):  (UMI)AAI8026564 
Date Available in IDEALS:  20141214 
Date Deposited:  1980 
This item appears in the following Collection(s)

Dissertations and Theses  Nuclear, Plasma, and Radiological Engineering

Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois