Development of mathematical model and numerical simulation of plasma ignition of flammable mixture with microwave subcritical streamer discharge.

The study of ignition of flammable mixtures by a microwave discharge is of interest for the design of propulsion systems with increased reliability and possibility of the use of lean fuel/air mixtures. A mathematical model for estimating plasma heating and conversion caused by a microwave subcritical streamer discharge is developed. Pressure of the medium is 13.3 kPa, temperature is 300 K. Plasma is created by microwave discharge with flat mirror and initiator (thin antenna). The initiator is hollow, fuel mixture (propane/air) is pumped through it to the exterior medium. Power of microwave radiation is 1.5 kW. Air flows around the initiator with velocity varying from 11 to 500 m/s. The plasma region and its conductivity are set based on experimental statistics, this is a key feature that reduces the consumption of computing resources. The mathematical model consists of three main stages. At the first stage, the Boltzmann equation for the electron gas in unperturbed medium is solved. At the second stage, the Helmholtz equations and plasma domain are considered for microwave system under study. At the third stage, the Navier–Stokes and transport equations with external heat power and additional plasma reactions for a compressible medium are solved. The results of numerical calculations are compared with the data of a physical experiment. The proposed model gives approximate estimations of discharge parameters and flow quantities, while the requirements for computational resources and time are significantly reduced in comparison to traditional models. • Numerical model of microwave discharge ignition is developed. • The model is validated against experimental data. • Streamer discharge provides reliable ignition in supersonic flow. [ABSTRACT FROM AUTHOR]