Twodimensional vapor flow analysis in heat pipes
Abstract
The computer code AGATHE which is intended to evaluate axially symmetric heat pipes with compressible vapor flow at Mach numbers up to one and at all radial Reynolds numbers is discussed. The code evaluates empirical factors which describes turbulence. Heat input and output are modeled by describing liquid heat transfer loops. The method leads to nonuniform heating and cooling rates typical of actual heat pipes. The code is adapted to evaluate heat pipes in tubular geometry composed of a series of heat transfer and adiabatic zones of cylindrical or conical shape. The two dimensional mathematical problem is reduced to a number of ordinary differential equations, which are integrated by a RungeKutta scheme. The reduction is achieved by starting from the NavierStokes equation using the boundary layer approximation; this approximation introduces the main limitation of the code, restricting its use to the calculation of vapor ducts with large length to diameter ratios. The velocity profile is simulated by a power series; the ncoefficients of this series are determined such that at each axial position the radial pressure gradient is approximately zero, as specified by the boundary layer approximation.
 Publication:

Presented at the 1st SP100 Program Integration Meeting
 Pub Date:
 1984
 Bibcode:
 1984sppi.meet...13P
 Keywords:

 Boundary Layers;
 Heat Pipes;
 NavierStokes Equation;
 RungeKutta Method;
 Two Dimensional Flow;
 Vapors;
 Computerized Simulation;
 Flow Visualization;
 Fluid Flow;
 Mathematical Models;
 Velocity;
 Fluid Mechanics and Heat Transfer