Abstr:Natural and mixed convection boundary layers on vertical heated walls (A)
Underlying Flow Regime 3-06
The flow under consideration is a low mach number flow of a strongly heated gas inside a vertical circular tube. The experimental work of A.M.Shehata and D.M.McEligot which is used to define this UFR supplements and extends earlier data for internal flows in small tubes (D<13mm) with temperature dependent transport properties that could only provide integral parameters.
These recent data are used to assess turbulence models by comparing measures and computed distributions of the mean streamwise velocity and temperature in this well defined experiment involving strong influence on the initial turbulent field, of the variation of the gas transport properties and the thickening of the viscous layer (the so called laminarization effect) which are caused by intense heating at the wall. Intense heating is defined here by a ratio wall to bulk absolute temperatures greater than 2.5.
This UFR is of particular relevance for the design of gas cooled nuclear reactors and the use of a gas as a coolant in power generation systems.
Contributors: André Latrobe - CEA / DRN / Department de Thermohydraulique