Impact of aerospike geometry and jet cooling on aerothermal performance of high-speed blunted bodiesOA

Effective aerospike configuration is crucial for aerothermal performance around the blunted nose of high-speed vehicles.The presence of aerospike changes the flow field,affecting the drag and aerodynamic heat loading in both supersonic and hypersonic flows.Computational approach is used to study the flow fields around a hemispherical blunted body with conical,hemispherical,and flat-faced aerospikes to obtain the optimized configuration of the aerospike.Different ratios of aerospike length to the blunt body diameter are analyzed for optimum aerodynamic effect on the body.The results showed that when the aerospike length is equal to blunt nose diameter for flat-faced aerospike;it possesses a drag coefficient of 0.32 which is significantly less than that of a simple blunt body of 0.79 at 0°incidence.Increasing the spike length ensures a higher reduction of drag.The flat-faced spike of length twice the diameter of blunt nose has reduced the drag by 74%to a larger extent whereas the smaller length reduced the drag by 59%.Changing the orientation of the body with the freestream direction diminishes the drag reduction capability of aerospike.The drag coefficient is minimum at 0°angle of attack and increases with the incidence angle.Aerodynamic heating is a concern at hypersonic speeds often rises the air temperature to 1800 K at Mach 6.To neutralize the high heat,ejection of coolant jet from the tip is analyzed to ensure cooling around the nose region.Different coolant jet velocities and ejection hole diameters are examined.Higher jet velocity causes less heat transfer towards the nose surface because of increasing the shock stand-off distance.A larger ejection hole provides more effective cooling by reacting more with the hot surrounding and the shock wave weaken or deflected to a greater extent compared to the smaller hole.The average surface temperature of blunted nose reduced to 605 K for 2 mm ejection hole at 320 m/s jet velocity whereas more cooling capacity has been achieved for 3 mm hole that lowers further to 500 K.