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Accession Number:
ADA106782
Title:
Transient Effects in Turbulence Modelling.
Descriptive Note:
Doctoral thesis,
Corporate Author:
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
Report Date:
1979-12-01
Pagination or Media Count:
277.0
Abstract:
Measurements of turbulence field data are reported for recirculating water flows under steady-state and transient flow conditions in an improved 115 scale FFTF outlet plenum test-cell. A dual-channel Laser Doppler Anemometer is used, and a unique method for performing transient measurements is developed and analyzed. The experimental behavior is predicted with a modified version of the VARR-II fluid dynamics code, and the suitability of using the steady-state turbulence model closure assumptions for analysis of transient flows is evaluated. A relationship between K-sigma and K-epsilon turbulence models is derived, and the two models are found to be nearly equivalent. Steady-state and transient mean velocity data are well-predicted throughout most of the test-cell. Calculated spatial distributions of the scalar turbulence quantities are qualitatively similar for both models however, the predicted distributions do not match the data over major portions of the flow area. The K-sigma model provides better estimates of the turbulence quantity magnitudes. The predicted results are found to be highly sensitive to small changes in the turbulence model free parameters and to depend heavily on the levels of inlet turbulence.
Distribution Statement:
APPROVED FOR PUBLIC RELEASE
