The ‘Smart’ Sphere: Experimental Results

Abstract

The ‘Smart’ sphere is a small self-equipped datalogger having 25 mm outer diameter with a built-in sensor for pressure or temperature measurements. This sphere has the capability to receive commands by wireless techniques and also stores the data continuously in its internal memory. These data can subsequently be transferred by wireless transmission to a computer for detailed analysis. Test runs using the sphere have been carried out to validate accurate functioning of the pressure and temperature sensor. The surface pressure measurements were performed using the sphere with a built-in pressure sensor inside the wind tunnel, in which the air velocity was varied. A Finite Volume technique (FLUENT 6.1) was used to simulate the flow over the sphere in the wind tunnel. The overall pressure distribution and the velocity distribution over the sphere have been obtained from these computations. The experimental and numerical results are in good agreement with each other. Additionally experiments with a free moving ‘Smart’ sphere with built-in temperature sensor have been carried out in a liquid column with a temperature gradient. It has been found that sphere has the capability to measure the temperature gradient rapidly and accurately as it passes through the column. The temperature measured by the sphere is compared with the reference temperature measured by 16-channel temperature datalogger and found to have good agreement with each other.