Numerical Simulation of Supersonic Carman Curve Bodies with Aerospike

Drag reduction is one of the important problems for the supersonic vehicles. As one of the drag reduction methods, aerospike has been used in some equipment because of its good drag reduction effect. In this paper, the numerical simulations of Carman curve bodies with different lengths of the aerospike and different radius of the flat cylindrical aerodisk in supersonic flow freestream are investigated. Based on the numerical simulations, the mechanism of drag reduction of the aerospike is discussed. The drag reduction effect influence of the parameters of the aerodisk radius and the aerospike length on the Carman curve body is analyzed. The aerodisk radius within a certain range is helpful for the drag reduction. The change of length of the aerospike has little effect on the drag of Carmen curve bodies. The drag reduction effect of the same aerospike becomes worse with the increase of the incoming Mach number.

Computational study of the cavity flow over sharp nose cone in supersonic flow

Heat and drag reduction on the nose cone is a significant issue for increasing the speed of the supersonic vehicles. In this paper, computational fluid dynamic method is applied to investigate the thermal and drag coefficient on the sharp nose cone with different cavity shapes. In order to simulate our model, the CFD method with SST turbulence model is applied to study the flow feature and temperature distribution in the vicinity of the nose body. The effect of depth and length of the cavity on the thermal characteristic of the nose cone is comprehensively investigated. In addition, the influence of the number of the cavity in the thermal performance of the main body is studied. According to our results, increasing the length of the cavity highly efficient for the reduction of the drag at Mach = 3. As the Mach number is increased to 3, the number of the cavity becomes a significant role and it is observed that case 9 with four cavities is more efficient. Obtained results also show that increasing the cavity depth declines the temperature on the main body. Our findings confirm that the main source of the expansion is the edge of the cavity.

Velocity Control Based on Active Disturbance Rejection for Air-Breathing Supersonic Vehicles

This paper investigates a velocity tracking control approach for air-breathing supersonic vehicles with uncertainties and external disturbances. Considering angle of attack is difficult to be precisely measured in practice, extended state observer technique is introduced into the state reconstruction design. In order to avoid possible oscillations in the design of the traditional extended state observer (TESO), a modified extended state observer (MESO) is developed, where a new smooth function is proposed to replace nonsmooth function of TESO. On the basis of it, an active disturbance rejection controller (ADRC) is designed for velocity control systems. Simultaneously, the closed-loop stability is rigorously proved by using Lyapunov theory. Finally, numeric simulations are conducted to validate the effectiveness of the proposed method.

Numerical Investigations on Thermoelectric Recovery of SiC Ceramics for Supersonic Vehicles Structures

The thermoelectric SiC structural materials for supersonic vehicles can convert intense aerodynamic heat to electricity simply by temperature difference. A general model of nose tip is developed to predict the thermal-electrical energy con-version performance of the thermoelectric SiC materials. The temperature distributions of model was obtained by solving the Navier-Stokes (N-S) equations and the heat conduction equation. The largest temperature difference between the hot side and cold side of the hypothetical thermoelectric module is about 275 K. With the thermoelectric properties assumed constant in the presence of temperature gradient, the output power and thermoelectric efficiency of the model are calculated. The maximum of thermoelectric efficiency and output power of the model are 0.4×10-3W and 1.6×10-4%, respectively, at a current of 0.014 A. The thermoelectric performance of the model shows great potential for the application of SiC ceramic structures to thermoelectric generation from aerodynamic heat on supersonic vehicles.