Study On The Cool Flow Field In Trapped Vortex Combustor With Air Injection

As one new type of Combustor with the character of high efficiency,low pollution, and low lean burnout(LBO),the trapped vortex combustor(TVC) has made numerous scholars pay much attention on it all over the world.It appears in 90s of 20^th century, and now has been developed into the High Pressure TVC as the fourth generation.In order to study the effect of various air injection parameters in fore-body and after-body on the flow field of TVC,especially on the field characteristics of partial trapped vortex cavity for flame stabilization,the amount,intensity,stability,distribution of trapped vortex and total pressure loss of TVC.In this paper,the numerical simulation has been carried out on various air injection location of the after-body,various air injection holes diameter of fore-body and after-body and various air injection Mach number of fore-body and back-body,then make detailed analysis on the flow field characteristics and changes of TVC flow field.The results show that:two groups of vortex which in opposite rotational direction, the similar shape and distribution formed in trapped vortex cavity,they are helpful to improve combustor stability.The outlet total pressure increases gradually and the average velocity decreases gradually with the after-body air injection position out-shift, the lower average velocity is helpful to form the stationary flame.When the fore-body air injection holes diameter is three times to after-body's,the total pressure loss of outlet are the smallest,as well as the average velocity in the vortex cavity which is helpful to form the stationary flame.In condition of the same fore-body air injection speed,the total pressure increases gradually with the after-body air injection speed increases gradually;In condition of the same back-body air injection speed,the total pressure and its change rate increases gradually with the fore-body air injection speed increases gradually;it is significant for forming low velocity flow region to choose the lower as possible because the for-body air injection speed effects on the change of average velocity in vortex cavity which is much greater than the after-body air iniection speed.