Engineering topics
Publications and source records attributed to Tannehill, J. C..
A time dependent finite difference method used to calculate blunt body flows with impinging shock is reported. The use of the method to predict maximum heat rates and pressure is discussed.
Two-dimensional viscous blunt body flows with an impinging shock have been computed using a time-dependent finite-difference method which solves the complete set of Navier-Stokes equations for a compressible flow. For low Reynolds number flows, the entire flow field, including the bow shock and impinging shock, has been captured in the computation. For higher Reynolds number flows, the bow shock is treated as a discontinuity across which the Rankine-Hugoniot equations are applied, while the boundary layer and interaction regions are captured as before. Using this latter shock-fitting approach, a Type III shock interaction flow field has been computed with flow conditions corresponding to the space shuttle orbiter freestream conditions at 61 km (200,000 ft).
Two- and three-dimensional, viscous blunt body flows with planar impinging shocks are computed using an explicit, time-dependent, finite-difference method to solve the complete set of Navier-Stokes equations. The bow shock is treated as a discontinuity, while all interior shock layer detail such as shear layers, shock waves, jets and the wall boundary layer are automatically captured in the solution. Numerical results are presented for cases in which planar shock waves of different strengths and orientations are allowed to impinge on the flow field surroundings an infinite cylinder resulting in two- and three-dimensional shock interference patterns. The numerical results are compared with experiment.
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Computer programs were developed which compute the thermodynamic properties of equilibrium air for use in either the time-dependent or shock-capturing computational methods. For the time-dependent method, tne NASA-ARC RGAS computer program was modified to allow internal energy and density to be used as the independent variables. In addition, simplified-curve fits for p = p(e,rho), a = a(e,rho), and T = T(p,rho) were devised to reduce computer time. For the shock-capturing method a simplified curve fit for h = h(p,rho) was made. These approximate curve fits may be particularly useful when employed on advanced computers such as the Illiac 4 or the CDC Star since they avoid the cumbersome table-lookup feature of the RGAS program.