Numerical Study of the Impingement of a Supersonic,Axisymmetric Jet on a Flat Plate

摘要

A numerical method for studying the flow field of anrnunder-expanded axis-symmetric jet created by arnconverging-diverging nozzle and impinging on a flatrnplate is presented. The calculation domain of interestrnis a region that contains all the features of the jet thatrnleaves the nozzle and impinges onto the plate. Axialrnsymmetry of the domain allows a reduced 2-rndimensional model to be used.rnFLUENT software is utilized to solve the continuity,rnmomentum and energy equations using a coupledrnimplicit scheme. The ideal-gas law is used torndetermine the gas density along with a k- ε turbulencernmodel with a special modification to account forrncompressibility effects. In addition, the temperaturerndependency of viscosity has been taken intornconsideration.rnA number of different modeling techniques arerninvestigated including different approximations tornaccount for the flow inside the nozzle. Performancernof non-equilibrium wall functions for near-wallrnturbulence treatment is compared with standard wallrnfunctions and multi-block structured rectangular gridsrnas well as triangular grids are implemented andrncompared. Modifications necessary to apply thernmethod to the 3-dimensional case are discussed.rnThe plate is far enough from the nozzle exit so that arnset of expansion and compression waves form. Arndiscussion of these waves and other features of thernflow field such as a recirculation region close to thernplate are presented. The flow is found to bernextremely complex due to the interactions of thernshock waves in the free jet and those created due tornthe existence of a barrier.rnThe numerical model is evaluated by comparisonrnwith an existing Shadowgraph image and withrnprevious simplified numerical results.