Recent extensions and applications of the ‘CST’ universal parametric geometry representation method

For aerodynamic design optimisation as \Veil as for multidisciplinary design optimisation stlldies , it is very desirable to limit the number of the geometric design variables. In Ref I , a ' fundamental' parametric :Jcrofoil geometry represcntation method was presented. The method included the introduction of a geometric 'class function/shape function' transformation technique, CST, s ueh that roLlnd nose/sharp aft end geometries as well as o ther c lasses of geometries could be represented exactly by analytic well behaved and simple mathematical function s having easily observed physical features, The CST method was s hown to dcscrihe a n cssentially limillcss dcsign spacc composed entirel y of analytically smooth geometri es. In Ref. 2, th e CST methodo'iogy was extended to more gene ral three dimensional applications such as wing, body, ducts and nace ll cs. It was shown that any general 3D geometry can be repre­ sented by a distribution of fund amental shapes, and that th e 'shape function/c la ss funct ion ' methodology can be used to describe th e fundame ntal shapes as wcll as thc distributi ons of the fundamental shapes, A number of applications of the 'CST' method to nacelles, ducts, wings and bodies were presented to illustrate th e versatility of this new methodology, In this paper, the CST tllethou is extended to include geometric warping such as variable camber, simple flap, aeroelastic and flutter deflections. The usc of the CST method for geometric morphing of one geometric shape into another is a lso shown. The use of CST analy ti c wings in design optimisation will also be discussed.