Experimental Investigation on the Effect of Bell Mouth on Nozzle Performance

Nozzle is an important component of wind tunnel. Its main functions: conversion of static pressure to dynamic pressure and reduction of turbulence intensity and helping in uniformity of the velocity profile in the test section of wind tunnel. In order to reduction of wind tunnel building costs, in some wind tunnel special vertical type, setting chamber may be replaced by a bell mouth at the nozzle inlet. Experimental methods such as hot wire anemometry have been used in this research. Result show that the effect of nozzle in blowing and suction type of wind tunnels is similar. Effect of bell mouth at the nozzle inlet is not significant for turbulence intensity reduction, but bell mouth of the nozzle inlet reduce the losses of nozzle about 7%.