The Theory of Burning of a Monopropellant Droplet—Variable Properties

Abstract

Abstract The problem of the burning of a monopropellant droplet has been studied considering variable properties. It is shown that the burning rates as obtained by using constant property assumption compare well with those obtained by considering variation of properties, provided the constant properties are evaluated at a suitable average temperature. The exponent p in the correlation [Mdot] a ∼ [Rdot]sa p ([Mdot]a is a dimensionless mass flow rate and Rsa is a dimensionless droplet radius) is shown to vary between the limits 1 and 2; p = 1 for pure vaporization and p = 2 for strong burning. The same limits are attained for very large activation energy and/or very small droplet radius, and for very small activation energy and/or very large droplet radius respectively. A simple explicit expression for [Mdot]a in terms of [Rdot]sa B (transfer number) and τ c (the centroid of the reaction rate) is suggested.