Numerical Studies of a Trapped Vortex Combustor in a Small Ramjet with Spinning Motion

报告人:  Prof. Randy S. M. Chue 

                  (Email: Randy.Chue@alum.mit.edu)

School of Mechanical and Aerospace Engineering,

Nanyang Technological University, Singapore

时间：2016年9月21日(周三) 9:30

地点：中国科学院力学研究所1号楼312会议室

报告摘要：

This presentation is on the numerical studies of a Trapped Vortex Combustor (TVC) to be applied in a small-size ramjet that spins during flight. The ultimate objective is to develop a generic subsonic combustor that has robust performance over a wide range of operating conditions. The main challenge in designing a small combustor is that there is limited space available for mixing and burning the fuel due to the short residence time.  The TVC is investigated as an approach to provide fuel-air mixing and flame stabilization by holding a pilot flame inside a cavity instead of exposing it to the main flow.

The example application being considered is a ramjet engine that is installed in a spin-stabilized projectile that spins at 30,000 RPM during flight. The combustor has a simple round geometry with a diameter of 100 mm and is designed for flight Mach numbers from 2.5 to 4.0.  The design studies include the optimization of the cavity dimensions in order to obtain a stable cavity vortex and the design of a fuel injection scheme that yields the best combustor performance.  The results of the spinning TVC show that Coriolis forces generate strong three-dimensional flows, thereby altering the cavity vortex and the recirculation zone in the combustor. Centrifugal forces also lead to stratification of different density streams, which must be balanced by a strong radial pressure gradient. The results show that the TVC provides good overall performance even under spinning motion.