Study on the Ignition Process and Characteristics of the Nitrate Ester Plasticized Polyether Propellant

Xiaoting Yan,Xudong Na,Liya Huang,Zhixun Xia,Chuanbo Fang,Yunchao Feng,Likun Ma

doi:10.1155/2020/8858057

Abstract

In this study, a CO2 laser ignition experimental system was built to study the ignition process and characteristics of the Nitrate Ester Plasticized Polyether (NEPE) propellant. The effect of the energy density, ingredients, and the grain size distribution of the propellant on the ignition process was investigated using a CO2 laser igniter, a high-speed camera, and a tungsten-rhenium thermocouple. Four types of NEPE propellants were tested under different laser heat fluxes, and the ignition delay time, the ignition temperature, and the ignition energy were obtained. Experimental results show that the ignition process of the NEPE propellant can be divided into three stages, namely the first-gasification stage, the first-flame stage, and the ignition delay stage. When the energy density is lower than the ignition energy threshold, the ignition process cannot be achieved even under continuous energy loading. The increase of the energy density can lead to the decrease of the ignition delay time but has little effect on the ignition temperature. The ingredients and grain size distribution have great effects on both the ignition delay time and the ignition temperature. The grain size effect of aluminum is the largest compared with that of Ammonium Perchlorate (AP) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), while the grain size effect of AP is larger than that of HMX.

Highlights

The solid propellant is the main energy source for solid rocket motors, which makes it important to increase its specific impulse [1, 2]
After the first-gasification instant, the gasification area kept expanding with heat accumulating on the surface and more gas escaped from the surface, as Figure 4(c) shows (c) at the instant of t = 0:095 s, the first visible flame appeared, and this instant was called the first-flame instant
We found that even continuous laser cannot ignite the sample when the laser energy density is lower than 43.29 W/mm2, which proves the existence of an ignition energy threshold in the ignition process of Nitrate Ester Plasticized Polyether (NEPE) propellants

Summary

Introduction

The solid propellant is the main energy source for solid rocket motors, which makes it important to increase its specific impulse [1, 2]. The Nitrate Ester Plasticized Polyether (NEPE) is a significant breakthrough during the development of highenergy solid propellants It combines the advantages of both the composite propellant and the double-base propellant, which means that it has both high-energy and good mechanical properties [3]. Ulas and Kuo [10] studied the ignitibility of six types of solid propellants under different CO2 laser heat fluxes and chamber operating conditions. They compared first gas evolution times and first light emission times of different propellants. Ali et al [11] plotted the delays as a function of irradiance on log-log axes They thought that thermal diffusion and fixed surface temperature ignition criterion are likely dominant parameters governing the ignition time. They measured the ignition time using a “first-light” criterion from the high-

Methods

Results

Conclusion