Modeling of momentum transport of axially parallel turbulent flows in rod cascades
Abstract
Problems and boundary conditions of the turbulent flow in heat exchangers, especially for nuclear fuel elements, are treated using mathematical models. Rod cascade flow and the physical fundamentals of turbulent flows are introduced. It is shown that the momentum transport phenomena can be separated into the radial and azimuthal directions. The geometrical characteristics of rod bundle geometries and a regression analysis are considered. The correlation coefficients for the wall parallel vortex viscosity are determined using a numerical optimization method. The order of magnitude of the secondary flow occurring perpendicularly to the main flow direction are determined to be 1 pct to 2 pct of the average axial velocity. The results obtained with the code VELASCOBS are superior to those of previous codes. The azimuthal vortex viscosity is the decisive parameter, and secondary flow is not important for wall parallel momentum transport.
 Publication:

Ph.D. Thesis
 Pub Date:
 1986
 Bibcode:
 1986PhDT........13N
 Keywords:

 Cascade Flow;
 Mathematical Models;
 Momentum Transfer;
 Turbulent Flow;
 Correlation Coefficients;
 Heat Exchangers;
 Nuclear Fuel Elements;
 Secondary Flow;
 Vortices;
 Fluid Mechanics and Heat Transfer