Research On Integration Design Methodology Of Aerodynamic Shape For Hypersonic Aircrafts

A hypersonic aircraft is usually defined as the aircraft with a flight speed above five times of the local sound speed.Since the extremely high flight speed,hypersonic aircrafts have great advantages in transportation efficiency and battlefield survivability,and thus this type of aircraft has a great potential for applications in both civil and military field.However,the development of hypersonic aircraft is difficult because it involves hypersonic aerodynamics,thermodynamics,combustion,materials and so on,and these subjects are highly coupled.Therefore,the technology of hypersonic aircraft is a research hotspot all the time,and any progress of the technology has a great influence on the development of economy and military equipment.Among all the core technologies of hypersonic aircraft,the aerodynamic shape design has the highest priority,which provides a solid foundation to further development.An aerodynamic shape dominates not only the basic flight performance but aslo the structure design,the load arrangement and the maneuverability.Since the flight environment of hypersonic aircraft is worse than that of the conventional aircraft,much more consideration should be taken into the aerodynamic shape design.In particular,the different aerodynamic components should utilize a coupled design,and the single component is expected to have versatile performance.Based on the analysis of known design methods,the research work is focus on the integration design method of aerodynamic shape for hypersonic aircrafts.In this dissertation,the concept of integration design is extended.It means not only the coupled design among different components but also the overall design involved several aspects of performance in a single component.In order to achieve the integration design of hypersonic aircrafts,a range of methods are researched and improved,such as design optimization method,flow field numerical simulation method,geometric parameterization method and waverider generation method.The most significant work and the major innovations are as follows:(1)A multistage optimization framework is proposed to improve the overall performance of hypersonic inward-turning inlet.In the first stage,the parent flow is optimized in order to improve the total pressure recovery and flow uniformity.In the second step,the inlet aerodynamic performance is optimized by the variation of lip planar shape.Lastly,two technologies of algebraic shape transition and boundary layer correction are employed for the practicability improvement.In the design process,the variance of mass flow weighted Mach number is firstly introduced as the index of flow uniformity,and a streamline-integration based method is proposed to achieve the inlet inviscid drag rapid prediction.The advantage of the multistage optimization framework assures the excellent overall performance of the design result,and it is also favorable for alleviating the negative influence induced by a single aspect improvement on the other aspects,reflecting of the design ideology of “Integration and Compromise”.(2)A domain-shift space-marching algorithm is developed to accelerate the supersonic flow field numerical simulation,and this method is employed to the integration design of hypersonic aft-body and nozzle.The domain-shift space-marching algorithm divides the whole computational domain into several sub-regions along freestream direction,and the computation in each sub-region still follows the conventional implicit time-marching algorithm.The essence of the algorithm is deviding the original high-dimensional matrix into several low-dimensional matrixs,and then the computation process is accelerated.In order to insulate the influence of the downstream flow characteristic on the upstream computation,a characteristic boundary condition based on local linearization is employed to the outlet of each sub-region.The numerical results show that the solver with the algorithm can precisely and rapidly simulate the supersonic flow field around aft-body and nozzle,providing convenience to the integrated design of these two components.(3)A novel wing-body configuration and inward-turning inlet integration design method for hypersonic cruise aircraft is proposed.Firstly,a patched class shape transition(CST)method is proposed to parametrically model the no-inlet configuration.The patched CST enlarges the design space of components on the premise of guaranteeing the configuration integrity via special constraints imposed on the interface across the adjacent surfaces.Secondly,a principle to instruct the inlet lip generation is proposed for the integration design,and the designed inlet is installed via a cut of the no-inlet configuration.Lastly,the inlet-included configuration is established by the surface re-generation with the help of COONS surface modelling method.At the design point,numerical simulation results show that the lift-to-drag ratio of the configuration is as high as 5.2 and the inlet works well with a high level of compression efficiency and flow uniformity.The achievement of design targets turns out that the integration method is efficient and practical,and the major concern of balancing the aerodynamic performance against the requirements for efficient propulsion is well addressed.(4)A design method of the waverider with a controllable planar shape is proposed to achieve the waverider wide-speed-range integration design.The core of this method is to establishing a geometric relationship among the flow capture curve,the inlet capture curve and the planar shape curve.According to the relationship,the planar shape curve is introduced as a design-driving parameter and the planar shape customization is easily achieved during the design process.To the engineering point of view,a series of planar shapes are favorable for the improvement of low-speed performance,thus these low-speed-friendly planar shapes are employed to the waverider generation for a wide-speed-range integration design.The design results show that the planar shapes are controlled effectively and precisely by the prescribed planar shape curves.The numerical simulations indicate that the planar shape customization does not destroy the favorable characteristics of the waverider and consequently high lift-to-drag ratio under hypersonic flight conditions.Furthermore,the low-speed performance is significantly improved.Since the planar shape are specified by an engineering point of view,the improvement is efficiently achieved at a low cost by avoiding the complex numerical simulation related to the conventional waverider designs.