Implication of air-throttling on combustion characteristics of cavity-strut based scramjet combustor

Abstract

The present study numerically investigates the implication of air throttling on the combustion performance of ethylene fueled cavity-strut-based scramjet combustor using three-dimensional Large Eddy Simulation. With the augmentation of combustion performance by throttling being established, the effects of the mass flow rate of throttling and its location on the combustion performance are discussed. Our results indicate a strong interplay of flow rate and location of throttling on the combustion performance. Further, it is observed that with the introduction of air throttling there is enhancement in combustion efficiency due to the generation of pre-combustion shock train. The optimum mass flow rate of throttling enhances the mixing of fuel and air due to the shock-shear interactions increasing recirculation inside the cavity. Furthermore, the location of throttling essentially dictates the extent and intensity of the recirculation zone pinpointing a fixed zone and air throttling further upstream or downstream deteriorates the combustion performance. Optimum combustion efficiency is attained when air throttling is about 20% of the inlet mass flow rate at 83.6 mm from the cavity aft.