Numerical simulation of the outflow of two phase flow from detonation unit barrel

Ihor Zorik

doi:10.15587/2706-5448.2020.201928

Abstract

The object of research is the application of detonation coatings using cheap and safe energy sources without reducing the quality characteristics of the coatings. One of the significant drawbacks of the detonation-gas method, from the point of view of safety and cost, is the widespread use of acetylene-oxygen mixtures. To some extent, the use of propane-butane mixtures solves the problem, however, the energy parameters of the process are reduced, which leads to the search for a compromise solution - methylacetylene-allene fraction (MAF). This energy carrier occupies an intermediate position in terms of energy characteristics and at the same time is stable and safe. The use of various energy carriers requires detailed information on the dynamics of the behavior of detonation products and sprayed particles in the barrel of a detonation unit. In the course of research, the problem of the development of deflagration combustion, the transition to detonation inside the unit’s technological channel and the movement of the detonation and shock wave front based on the Navier-Stokes equations with a two-layer Menter’s turbulence model is solved. To calculate multiphase flows, a volume of fluid model (VOF) is used, which assumes that two liquids (or phases) or more do not mix and do not penetrate each other. The results of numerical modeling of the process of expiration of detonation products from the barrel of a detonation unit, as well as the heat exchange process between combustion products and powder particles, are presented. The velocities and temperatures of alumina particles are determined for various ratios of MAF/oxygen at the outlet of the process channel and in front of the substrate. The results of numerical modeling are compared with experimental data. It is shown that the model used adequately describes the heat transfer process. As a result of the studies, it is justified to use MAF as an energy carrier without reducing the quality of coatings of oxide ceramics. The developed mathematical model is suitable for modeling the process from any combination of gas components capable of detonating.

Highlights

Detonation spraying was originally implemented by the American company Union Carbide in the 1950s, which conti nues to create new patented developments in this area [1, 2]
It has been shown that acetylene-oxygen and other mixtures of hydrocarbon fuels with an oxidizing agent capable of detonating, for example, methane or propane-butane can be used as energy carriers
The mechanism of formation of strongly coupled coatings is determined by the intensity of both thermal and mechanical activation of the surface layers of the materials being joined

Summary

Introduction

Detonation spraying was originally implemented by the American company Union Carbide in the 1950s, which conti nues to create new patented developments in this area [1, 2]. It has been shown that acetylene-oxygen and other mixtures of hydrocarbon fuels with an oxidizing agent capable of detonating, for example, methane or propane-butane can be used as energy carriers. MAF (methylacetylene-allene fraction) is increasingly used in gas welding and metal cutting instead of acetylene Since it is cheaper and safer and is a mixture of methylacetylene (propine) and allene (propadiene), stabilized for safety reasons with propane, propylene, butane or other hydrocarbons in various combinations. Improving the operational properties of the most loaded parts of aircraft engines is possible using several approaches, such as the development of new materials, the improvement of manufacturing methods, and the use of new technological processes. Since the operational characteristics of parts and components of aircraft engines significantly depend on the quality characteristics of the surface and the surface layer, the use of various types of thermal spray coatings is relevant. The aim of research is to establish the laws of formation of the energy parameters of the applied powders (veloc ity, temperature), affecting the physical and mechanical properties of the surface layer, in particular adhesive and cohesive strength

Methods of research

Findings

Average value