Aerodynamic Design Of A University-type Hypersonic Ludwieg Tube Tunnel

Supersonic and hypersonic vehicles have always been the focus of development in major countries around the world.Their high-speed maneuverability has significant military strategic significance and broad civilian prospects.Over the past few decades,researchers have accumulated a large theoretical base and experimental data in the field of hypersonic flow research.However,due to its complex flow mechanism,some key problems remain unsolved,such as laminar/turbulent boundary layer transition and shock/boundary layer interaction mechanism.Therefore,basic research on supersonic aerodynamics is important.Conventional methods for performing supersonic aerodynamic studies include flight tests,numerical simulations,and ground tests.Among them,the ground test is relatively low in experimental cost,and the experimental measurement technology is relatively mature,so it is widely used in the study of hypersonic flow.Among the ground test equipments,the Ludwieg tube tunnel has the advantages of high unit Reynolds number and low construction and operation cost,which is very suitable for general research institutions to carry out basic flow mechanism research.The Laval nozzle is the key to the supersonic flow of the Ludwieg tube tunnel.The design quality directly affects the flow field quality of the wind tunnel.Therefore,the design of the Laval nozzle is the key to the aerodynamic design of the Ludwieg tube tunnel.In order to obtain a good wind tunnel design and accumulate the design experience of Ludwieg tube tunnel,this paper carried out the aerodynamic design of the Mach 6 research hypersonic Ludwieg tube tunnel.The aerodynamic design and optimization of the hypersonic Laval nozzle were carried out by applying numerical tools such as method of characteristics and computational fluid dynamics.In this paper,the design method of Witoszynski contraction section curve is improved.By rationally arranging the design parameters of Sivells method,the influence of each parameter on the expansion section contour and its flow field quality is systematically studied.Through the results of inviscid flow simulation,the inviscid nozzle contour with good flow quality was obtained,and the boundary layer was corrected properly to obtain the viscous contour.Through the numerical simulation of the wind tunnel model with a fast valve,the influence of the fast valve body on the flow quality of the nozzle outlet was studied,and the aerodynamic design of the excellent hypersonic Ludwieg tube tunnel was finally obtained.