ELECTRO-HYDRODYNAMIC ANALOGY SOLUTION OF CONFORMAL MAPPING OF EXTERNAL DOMAIN OF AN AIRPLANE FUSELAGE

Determination of bilinear transformation functions that mutually mapp conformally the exterior of an arbitrarily shaped given contour to exterior of unit circle is of practical importance in several fields of engineering. For solution of this problem, certain numerical techniques are available, suffering from either low accuracy or complicated procedures and long computer time disadvantages.In presented paper is applied an experimental computational technique based on the electro-hydrodynamic analogy.and method of trigonometric interpolation. Required mapping functions are assumed in form of power series with coefficients determined using images of points equally deviding the circle contour.Image points on given contour are determined by electro analogy on electrically conductive paper .The method is applied for conformal mapping of exterior of airplane fuselage sections with and without its horizontal tail surfaces, Mapping series proved to be convergent and fluently changing in harmony with fuselage body streamlining. The method is simple and economic with results of acceptable accuracy. More-over ,it is the only practical solution of conformal mapping problems of real non-idealized actual cross-sectional shapes of modern complicated wing-body combinations. Due to its relation to velocity potential and pressure distributions, longitudinal behaviour of mapping functions with fuselage stations can depict positions of unfavourable pressure gradient and assist its streamlining.