Paper 2: A Meter for the Determination of Local Heat-Transfer Coefficient

Abstract

This paper describes the development of a device for the measurement of local heat-transfer coefficient. Such a device was required to measure the local heat-transfer coefficients between heated air and the solid surface of a complex geometric shape, under steady-state conditions.

The meter described is based on a method suggested by Gardon (1)† where the heat flux into a thin constantan disc, arranged flush with the fluid-solid interface, produces a radial temperature gradient in the disc. Provision of suitable copper connections at the centre and periphery of the disc gives rise to an e.m.f. proportional to the radial heat flux.

This basic principle has been incorporated in an instrument which yields simultaneous measurements of both heat flux and surface temperature.

A theory for the meter under steady-state conditions is discussed and shown to be in good agreement with calibrations obtained in a specially designed rig.