Sunflower detonation

TL;DR

This paper presents simulations of a sunflower-shaped detonation pattern in a radially expanding supersonic reactive gas flow, highlighting its instability, cellular structures, and methods to confine it using obstacles.

Contribution

It introduces a novel visualization of sunflower-shaped detonation patterns and demonstrates how obstacles can stabilize and contain the detonation in a bounded region.

Findings

Detonation forms characteristic cellular patterns resembling a sunflower.

Obstacles can stabilize the detonation and keep it at a finite distance from the source.

The cellular structure creates complex shock wave and contact discontinuity patterns.

Abstract

In this fluid dynamic video we present simulations of converging two-dimensional detonation in a radially expanding supersonic flow of ideal reactive gas. The detonation is found to be unstable and leads to formation of characteristic cellular patterns. Without any obstacles in the flow, the detonation keeps expanding radially. To retain the wave within a bounded region, we place a number of rigid obstacles in the flow so that the detonation shock stands some distance toward the center from the obstacles. This leads to generation of reflected shock waves from the obstacles which help the detonation wave to remain at a finite distance from the source. The cellular structure of detonation creates beautiful patterns of shock waves and contact discontinuities within and after the reaction zone. The patterns often resemble a sunflower, hence the name of "sunflower detonation".