Study of Intra-Chamber Processes in Solid Rocket Motors by Fiber Optic Sensors.

Andrey A Zhirnov,Anton O Chernutsky,Kirill I Koshelev,Stanislav G Sazonkin,Alexey B Pnev,Dmitriy A Yagodnikov,Konstantin V Stepanov,Alexey O Novikov,Tatyana V Choban

doi:10.3390/s21237836

Abstract

In this study, an experimental study of the burning rate of solid fuel in a model solid propellant rocket motor (SRM) E-5-0 was conducted using a non-invasive control method with fiber-optic sensors (FOSs). Three sensors based on the Mach–Zehnder interferometer (MZI), fixed on the SRM E-5-0, recorded the vibration signal during the entire cycle of solid fuel burning. The results showed that, when using MZI sensors, the non-invasive control of solid fuel burnout is made possible both by recording the time of arrival of the combustion front to the sensor and by analyzing the peaks on the spectrogram of the recorded FOS signal. The main mode of acoustic vibrations of the chamber of the model SRM is longitudinal, and it changes with time, depending on the chamber length. Longitudinal modes of the combustion chamber were detected by MZI only after the combustion front passed its fixing point, and the microphone was unable to register them at all. The results showed that the combustion rate was practically constant after the first second, which was confirmed by the graph of the pressure versus time at the nozzle exit.

Highlights

In modern engines and, in a solid propellant rocket motor (SRM), energy conversion processes are characterized by extreme temperatures and released power.For example, the thermodynamic temperature is around 3600 K in the combustion chamber of the Ariane-V launch vehicle’s accelerator, EAP P241, which produces a thrust of7.08 MN [1]
Analysis of the Images of the SRM stages are shown in Figure 6, including start-up (a,b), operation
Itwhich isthe worth noting densed phase particles flowed out of the engine nozzle, is common for the the tracks com- of th phase particlesdensed flowedphase out ofparticles the engine nozzle, which is common for which the combustion flowed out of the engine nozzle, is common bustion products of powder and metal-containing fuels

Summary

Introduction

In a solid propellant rocket motor (SRM), energy conversion processes are characterized by extreme temperatures and released power.For example, the thermodynamic temperature is around 3600 K in the combustion chamber of the Ariane-V launch vehicle’s accelerator, EAP P241, which produces a thrust of7.08 MN [1]. There are methods for the invasive monitoring of such processes, for example, by inserting thermocouples into test holes This is simpler, but violates the integrity of the engine and probably changes the operation’s parameters. If we place thermocouples on the motor casing in a non-invasive way, the measurement obtained will be incorrect due to low thermal conductivity in the casing in the outer direction, sensor inertia, and the ambient temperature. In such conditions, fiber-optic sensors (FOSs) present a very promising solution for verifying the simulation data of engine processes [8]. New types of fiber promise to open new opportunities for such monitoring devices [26,27]

Methods

Results

Conclusion