A Rational Method to Choose Optimum Design for Two-Dimensional Contractions

Abstract

A review was carried out on the studies undertaken to obtain efficient shapes for the contraction designs. It is seen that before the advent of efficient digital computers around 1970, studies in this field Barger et al., Cohen and Ritchie, Johnson, Whitehead et al., Tsien were of analytical nature, i.e., the contraction profiles were obtained for some prescribed velocity distribution. However, after 1970, when the digital computers became widely available, most of the studies, Morel 1, Downie et al. 2 and Borger 3 have been directed at prescribing the contraction profile and computing the flow field. An important observation emerged from the review is that, most of the authors provided only qualitative criteria based on acceptable nonuniformity and avoidance of boundary layer separation to select contraction profile and none of them had determined the optimum profile even within the same family of profiles. It was also seen that no comparison of the performance of the profiles proposed by various authors had been made. Hence the present study was to evolve a rational method for qualitatively assessing the relative performance of various profiles and make the comparisons of the best performances of different family of profiles for two dimensional case. Since the cited references provide all the necessary information in respect of the profiles, the physical characteristics and governing evaluation of these profiles are not repeated here.