Novel and Simple Formulae to Calculate Air Molecular-Transport Properties of Momentum and Heat Transfer.(Dept.P)

Abstract

In this paper three novel and simple formulae are deduced to calculate the dynamic Viscosity, the kinematic viscosity and thermal conductivity of air on knowing air temperature and pressure. These formulae can be ap p lied under a wide range of working conditions. They can be used at any temperature (up to 2500 oK) and at p ressures below 10 Atmospheres. Formula (3) gives the dynamic viscosity of air while formula (6) gives its thermal conductivity on knowing air temperature. Formula (5) gives the kinematic viscosity of air as a function of air temperature and pressure. Each formula gives the required property in one step calculation with an excellent accuracy as only ± 3% maximum deviation from the available data in the literature is noted over that wide range of working conditions. From these formulae momentum and heat-transfer calculations which need the knowldge of viscosity and thermal conductivity of air can now be done on knowing air temperature and p ressure without referring to the literature to get these p hysical properties. In this way a great simplicity and availability in air calculations is realized.