Study On Drag And Heat Reduction Characteristics Induced By Spike-jet Hybrid Strategy Of The Hypersonic Vehicle

Drag and heat reduction is an important issue in the engineering application of hypersonic vehicles.The severe aerodynamic heating will induce the ablation of the aircraft head materials,and it will damage the electronic devices,which is a serious threat to the flight.On the other hand,the huge shock drag will affect the lift-drag ratio of the aircraft,leading to the reduction of range and speed.In this paper,a series of key problems in engineering application,such as the characteristics of the drag and heat reduction,the law of influence factors and the selection of jet directions and locations,are deeply studied.And this paper is mainly divided into three parts:the first part is the drag and heat reduction characteristics of the jet-spike hybrid strategy;the second part is the influence of the jet directions on the hybrid strategy;the third part is the comparative study on the characteristics and efficiency of the drag and heat reduction of hybrid strategy based on different jet locations.Firstly,for the hypersonic flow field,an in-house code was developed with structure grid method and the reliability of the current numerical approaches ware validated.Based on a novel spike root oblique jet strategy,the grid independence analysis was carried out,and the drag and heat reduction characteristic of the hybrid strategy and non-jet strategy were compared systematically.Furthermore,the influence of some factors(the spike length,oblique jet pressure ratio and the size of the aerodisk)on the hybrid strategy flow field and the distribution of aerodynamic parameters along the blunt surface were investigated.And then,the influence of jet direction ignored by most literatures was considered,and its influence on the performance of drag and heat reduction was studied.The flow characteristics and the parameters along the bunt surface of the spike root opposing,oblique and lateral jets were obtained by numerical method.Furthermore,the total drag,the heat load of the blunt body and the peak Stanton number value under different jet directions were compared.Finally,the optimal jet direction was obtained.Finally,five popular hybrid devices with different jet locations are summed up.Those five strategies were compared under the same condition through numerical simulation.Due to the great difference in the distributions of the parameters along the blunt surface among different hybrid devices,three parameters were introduced to evaluate the drag and heat reduction efficiency.The performance of different hybrid devices in reducing the total drag,the peak value of Stanton number and the heat load are comprehensively investigated,which provides a reference for the engineering application.In summary,based on the technology of drag and heat reduction of hypersonic vehicle,the drag and heat reduction characteristics of a novel spike root oblique jet hybrid strategy was investigated by numerical simulation.On this basis,the influence of the jet directions on the flow field and thermal protection performance was analyzed.Finally,five popular hybrid strategies were compared.The research of this paper has reference significance for the engineering application of the hybrid strategy.