Session: 12-12 Computational Techniques

Paper Number: 81307

81307 - Large Eddy Simulation of Energy Transport in Highly Compressible Transverse Jets 

Large eddy simulation is adopted to study the thermal energy transport and mixing process of a round laminar jet in a fully turbulent crossflow. Inclined jets in compressible crossflow is the basic form of film cooling in high-pressure turbines. Therefore, a canonical model of plate film cooling with cylindrical orifices structure is employed to study the heat transfer process in high Mach number flows. In this study, the energy equation of highly compressible fluid is systematically analyzed and the contributions of each term in the equation are compared quantitatively. Turbulent enthalpy transport is found to be in the same order of magnitude as the advection term associated with mean motion and thus is not negligible when considering the convective heat transfer problem of film cooling, which differs from the conclusion drawn from the incompressible-jets-in-crossflow studies. The inaccuracy of RANS turbulent modeling caused by counter-gradient transport of enthalpy is explained in detail and a more reasonable three-dimensional analysis method is proposed for in-depth mechanism analysis and turbulent model improvement. The numerical results also show that the contribution of mean motion to the overall kinetic energy dissipation in thermal energy transport is dominant in the near-field region where jets and crossflow interact and mix intensively while the turbulent kinetic energy dissipation term predominates in most other regions. Moreover, the irreversible increase in entropy caused by dissipation and heat transfer in the flow field is compared. The results show that the entropy production due to the latter one cannot be ignored when dealing with large temperature difference film cooling which is common in high-pressure turbines.

Presenting Author: Hao Guo Tsinghua University

Presenting Author Biography: PhD student of Tsinghua University<br/>Major: Engineering Thermophysics<br/>Main Research Interest: supersonic film cooling; large eddy simulation of compressible turbulent flow; shock waves in high-speed flow

Authors:

Hao Guo Tsinghua University
Yinhai Zhu Tsinghua University
Peixue Jiang Tsinghua University