THEORETICAL ANALYSIS ON THE EFFECT OF DIVERGENT SECTION WITH LAMINAR BOUNDARY LAYER OF SONIC NOZZLES

Hongbing Ding, Chao Wang, Yakun Zhao

Abstract

ISO toroidal-throat nozzle with a divergent section differs from the nozzle used for the theoretical research of Hall & Geropp and is highly likely to affect the flow field and discharge coefficient. In this paper, the influence of ISO-type conical divergent section on discharge coefficient was analyzed basing on inviscid transonic flow model and laminar boundary layer respectively. Two coordinate systems namely cylindrical coordinates and curvilinear coordinate were applied to research the velocity distribution of core flow and calculate displacement thickness. The results indicated the influence of conical divergent section decreases with increasing of diffuser angle and Reynolds number, while increases with divergent section length increasing. It meant that the discharge coefficient is significant influence by diffuser angle and divergent section length when the Reynolds number decreases to a certain value. The sonic nozzle which is miniaturized or applied to low Reynolds number flow should be carefully designed.

Keywords

sonic nozzles, discharge coefficient, divergent section, laminar boundary layer, Reynolds number, ISO 9300

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IMEKO-TC9-2013-105.pdf

DOI

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IMEKO TC

TC9 - Flow Measurement

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