Numerical Heat Transfer Model for a Heat-Barrier-Piston Engine with Hypergolic Combustion

摘要

Axisymmetric turbulent combustion flow with heat transfer has been modeled for a four-stroke engine exhibiting hypergolic combustion and containing a heat barrier within the piston. The boundaries of the solution scheme extend fixed distances into the piston and cylinder lining. In the model, a valve was simulated which has thickness for the purpose of heat transfer calculations and is infinitely thin for the purpose of fluid field calculations. A fuel injector was numerically modeled which gave good simulation of the type of injector used in current hyperglobic combustion research. The implicit finite-difference solution of the governing equations for the primitive variables was conducted in three regions, one fixed in space with time, one utilizing a stretching and compressing computational mesh and one which moved with time without stretching and compressing. An accuracy check of the computational code for the five primitive variables representing the non-combustion case was conducted by specifying an analytic expression for each of these variables and changing the source terms of the corresponding governing equations to make these analytic expressions into the solution computed solution with the specified analytic solution for the resultant set of modified equations. Comparision of the numerically computed solution with the specified analytic solution gave excellent agreement.