Abstract:

ESDU 01024 presents an example of the application of constrained multivariate optimisation techniques illustrating the use of mixed Computational Fluid Dynamics options in a dual design point study. To demonstrate the capability of the method fully, two disparate design points have been deliberately selected, one transonic (Mach number 0.71, lift coefficient 0.75 and Reynolds number of 20 million) calculated by BVGK used in viscous mode, and the other supersonic (Mach number 1.4, lift coefficient 0.05) calculated by an inviscid Euler code. The basic aerofoil is RAE 2822. The optimisation objective is to minimise a linear combination of the drag coefficient values at the two design points. Reduction of the objective function is to be sought by changes in the upper and lower surfaces, the leading-edge shape, and by deflection of simple leading- and trailing-edge flaps hinged at 15 and 75 per cent of chord respectively. ESDU 01024 is one of a series illustrating the process of using such optimisation techniques, indicating their advantages and revealing the kinds of problems that can arise. To facilitate this it is in narrative form. An introduction to the application of constrained multivariate optimisation techniques to the design of aerofoil section shapes is given in ESDU 99019.