CAS22 - FORTRAN program for fast design and analysis of shock-free airfoil cascades using fictitious-gas concept

A user-oriented computer program, CAS22, was developed that is applicable to aerodynamic analysis and transonic shock-free redesign of existing two-dimensional cascades of airfoils. This FORTRAN program can be used: (1) as an analysis code for full-potential, transonic, shocked or shock-free cascade flows; (2) as a design code for shock-free cascades that uses Sobieczky's fictitious-gas concept; and (3) as a shock-free design code followed automatically by the analysis in order to confirm that the newly obtained cascade shape provides for an entirely shock-free transonic flow field. A four-level boundary-conforming grid of an O type is generated. The shock-free design is performed by implementing Sobieczky's fictitious-gas concept of elliptic continuation from subsonic into supersonic flow domains. Recomputation inside each supersonic zone is performed by the method of characteristics in the rheograph plane by using isentropic gas relations. Besides converting existing cascade shapes with multiple shocked supersonic regions into shock-free cascades, CAS22 can also unchoke previously choked cascades and make them shock free

Shockless design and analysis of transonic blade shapes

A fast computer program was developed to eliminate the shocks by slightly altering portions of the contour of a given airfoil in the cascade. The program can be used in two basic modes: (1) An analysis for steady, transonic, potential flow through a given planar cascade of airfoils and (2) a design for converting a given cascade into a shockless transonic cascade. The design mode can automatically be followed by the analysis mode, which confirms that the flow field is shock free. The program generates its own multilevel boundary conforming computational grids and solves a full potential equation in a fully conservative form. The shockless design is performed by implementing Sobieczky's fictitious-gas elliptic continuation concept

Extended mapping and characteristics techniques for inverse aerodynamic design

Some ideas for using hodograph theory, mapping techniques and methods of characteristics to formulate typical aerodynamic design boundary value problems are developed. The inverse method of characteristics is shown to be a fast tool for design of transonic flow elements as well as supersonic flows with given shock waves

A new method for designing shock-free transonic configurations

A method for the design of shock free supercritical airfoils, wings, and three dimensional configurations is described. Results illustrating the procedure in two and three dimensions are given. They include modifications to part of the upper surface of an NACA 64A410 airfoil that will maintain shock free flow over a range of Mach numbers for a fixed lift coefficient, and the modifications required on part of the upper surface of a swept wing with an NACA 64A410 root section to achieve shock free flow. While the results are given for inviscid flow, the same procedures can be employed iteratively with a boundary layer calculation in order to achieve shock free viscous designs. With a shock free pressure field the boundary layer calculation will be reliable and not complicated by the difficulties of shock wave boundary layer interaction

Generic Supersonic and Hypersonic Configurations

Abstract: A geometry generator for preliminary aerodynamic design, parametric optimization and the preprocessing of CFD boundary conditions is presented. With emphasis on supersonic aircraft components, ranging from waverider caret wings to generic lifting bodies derived from recent aerospace research projects, the simple mathematical basis and its consequent use throughout various applications is illustrated

IUTAM Symposium Transsonicum IV

In the first group, work is devoted to inviscid steady and unsteady flow and toward their use in aeroelastic applications. With theories and models available from work reported in the past symposia, work remains to be done mainly for unsteady flow, even without the influence of flow viscosity. Local configurations of sonic locus, shock waves and flow boundaries have been subject to various mathematical approaches, work in this subject remains important also for passing the analytical knowledge base on to the younger generation of aerospace engineers. The second group of contributions is devoted to viscous flows. Fluid flow with viscosity adds phenomena which prohibit analytical treatment in many cases. Viscous-inviscid flow interaction in aerospace and in turbomachinery applications need a refined treatment of local interactions between shocks and boundary layers. A report about the European Transonic Windtunnel is presented as a mature experimental test facility for the aircraft industry to model realistic flight Reynolds numbers. With tremendous success in Computational Fluid Mechanics, this meeting was not intended to report about the status of Computational Fluid Dynamics (CFD). In the third group only a few innovative contributions follow a comprehensive review about the development of transonic CFD through the past four decades. Design rather than analysis seems to be a task requiring a systematic use of the transonic knowledge base. Reporting the status of practical design optimization in the industry is complemented by outlining novel strategies to arrive at optimization with affordable computer time. Applying optimization to the hardware of aircraft wings and helicopter rotors results in the development of flow control techniques which partly are brought to reality by an adaptation of shape components through mechanical devices: Progress in this field is reported by a fourth group of contributions. Renewed interest in supersonic civil transport (SST) resulted in a few research projects during the past decade. Inevitably an SST will have to pass the sonic flow regime which is still seen as an issue for both economical operation as well as for ecological problems stemming from the sonic boom. These problems are of a transonic nature, recent progress is being reported in the fifth group. Finally, in a small sixth group we present some results for real gas effects like dissociation and condensation. These will be useful for introduction into the operational methods dealing with ideal gas models