Investigation Of Hypersonic Inward Turing Inlet With Controlled Mach Number Distribution And Its Integrated Design

The development of a high performance hypersonic inlet system is critical to the success of the scramjet engine and hypersonic vehicle. The inward turning inlets offer the special advantages which cause extensive concentration recently. The design methods of the three dimensional inward turning inlet are still far from systematic. The integration of the inward turning inlet with the waverider forebody is in the phase of preliminary concept research. Therefore, the investigation of innovative concept and method for the inward turning inlet and waverider forebody is of great importance to promote the development of near-space hypersonic vehicle technology for our country.The existing design method of the inward turning inlet is specific. With further analysis of the inward turning inlets existed, an innovative design concept of the inward turning inlet called controllable Mach number distribution is proposed in this paper. It is well known that the basic flowfield is a key to the design of inward turning inlet. This paper utilizes the rotational method of characteristics and establishs a systematic design method of basic flowfield with controllable Mach number distribution. Furthermore, the concept is extended in designing waverider forebody. The proposed controllable Mach number distribution design method is combined with inward turning inlet to realize integration design.The objective of this paper is as following:First of all, the design method of controllable Mach number distribution is proposed according to typical axisymmetric basic flowfield with two waves and three regions. The basic flowfield is designed reversely from assigned compression surface Mach number distribution. The Mach number spatial distribution of the inner basic flowfield can be controlled by changing the Mach number distribution along compression surface. Moreover, the basic flowfields of different Mach number distribution laws are studied in detail. The characteristics of flowfield and the rules of major design parameters influencing on geometric and performance parameters of the basic flowfield are obtained, and the influence of viscosity is analyzed. The basic flowfield of arc tangent Mach number distribution has optimal overall performance that can be further improved by multi-objective optimization design. These can serve for following design and research of inward turning inlet.Based on the previously mentioned basic flowfield of controllable Mach number distribution, the inward turning inlets are designed utilizing streamline tracing technique. Numerical simulation results indicate that viscosity corrected inlets possess the similar wave system characteristics of the basic flowfield which could capture almost all the incoming flow. Mach number distribution law of the inlets is consistent with that of basic flowfield, so that a high-performance inlet could be designed by selecting appropriate Mach number distribution of basic flowfield. Based on the optimized basic flowfield of arc tangent Mach number distribution, the designed inward turning inlets offer better overall performance over a wide range Mach number. In order to get a more uniform exit plane, it is effective to reduce vortex region by grooving at downwash region. Grooving at separation region can efficiently improve inlet starting ability with less flow losses.Secondly, the design methods of axisymmetric basic flowfield of controllable Mach number distribution with four waves and four regions and center body consisting of four spline curves which could diffuse the reflected shock wave are proposed to reduce the leading incident shock and reflected shock strength of the basic flowfield, so that the compression efficiency improved significantly. The diffusing reflected shock center body axisymmetric basic flowfield of arc tangent Mach number distribution with four waves and four regions is designed by combining these design concepts. With this basic flowfield, an inlet with rectangular-to-circular shape transition is designed and conducted wind tunnel testing. Experimental results indicate that the topwall pressure distributions are arc tangent curve at design and off-design points. The inlet offers good overall performance and small vortex region, at design point(Ma=6.0), the total pressure recovery coefficient is 0.561 and the compression ratio is 26.2 at exit plane, and the major flow region is nearly two thirds of the exit plane. The results validate the feasibility of previous design method. Bleeding air at topwall can reduce the vortex region and improve the resisting back pressure ability.Thirdly, the design method of basic flowfield with controllable shocks strength is proposed to further improve the flexibility of axisymmetric basic flowfield with controllable Mach number distribution, that achieve the active adjustment of proportion between shock compression and isentropic compression. Applying the design method, a single incident shock basic flowfield with two shocks and three regions and double incident shocks basic flowfield with three shocks and four regions are designed, which offer high compression efficiency. Based on the double incident shocks basic flowfield, an inlet with circular shape intake is designed which has high mass capture ratio and compression efficiency. Based on the basic flowfield, the waverider forebody and inward turning inlet are designed to realize the respective internal waverider of the forebody and inlet integrated configuration.Finally, the inverse design method of external conical basic flowfield with controllable Mach number distribution is proposed to improve their controllability, the incoming flow can be efficiently compressed within short length. With this basic flowfield of arc tangent Mach number distribution, the waverider forebody is designed which offers high volume ratio, good waverider characteristics and exit uniformity. Then, based on the external conical and internal conical basic flowfields with controllable Mach number distribution, a design arrangement of integrating waverider forebody and inward turning inlet is proposed which achieves that internal and external flows are respective waverider. Besides, in order to realize integrated design of waverider forebody and inward turning inlet of hypersonic vehicle with two sides intake layout, the design method of the water-drop like entrance to circular shape transition inward turning inlet is presented, which could greatly improve the exit uniformity and inlet starting ability.