Real-Time Deep Throttling Tests of a Hydrogen Peroxide Hybrid Rocket Motor

Abstract

Hybrid rockets based on hydrogen peroxide strengthen the typical advantages of hybrid technology and eliminate its main issues. In fact, when the hydrogen peroxide is decomposed through a catalyst bed, it is possible to design hybrid motors that are simple, affordable, safe, green, storable, reliable, stable, efficient, and compact. Moreover, decomposed hydrogen peroxide is not limited by atomization issues and ignites spontaneously with the fuel, allowing for deep throttling and multiple reignition, pushing hybrids’ energy management capabilities to the top. This can be done simply by controlling the oxidizer mass flow to the combustion chamber. Being an incompressible and noncryogenic liquid, hydrogen peroxide mass flow is relatively easy to control. The authors’ research group has been developing lab-scale hybrid rocket motors that are particularly suited for energy management. A flow control valve has been specifically developed for this purpose. The flow control valve exploits the cavitation on an actuated pintle in order to choke the mass flow. The advantages of such a device, which is called a variable area cavitating venturi, are insensitivity of the mass flow to the downstream pressure variation and linearity of the mass flow with the throat area. The flow control valve has been designed at first, then characterized through static and dynamic cold flow tests. Afterwards, fire tests of a lab-scale hybrid motor have been performed in order to understand the throttling behavior of the complete system. Finally, a real-time control of the oxidizer flow valve, and, consequently, of the hybrid motor thrust, has been implemented and fire tested, showing the impressive on-demand energy management capability of this technology.