Pulcher-pulsed chemical rocket with green high performance propellants: second year project overview
PulCheR (Pulsed Chemical Rocket with Green High Performance Propellants) is a project co- funded by the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreementn°313271.More in detail, the project has been proposed in response of the fifth space call (FP7-SPACE-2012-1), under the topic Key Technologies for In-Space Activities (SPA.2012.2.2-02). Radical innovation, disruptive technologies, research topics with long term vision, high-risk ideas, development of components with highly advanced performances as well as new system concepts and wide range of research opportunities were the keywords of the call. In the light of this, the PulCheR project has been proposed at the end of 2011 and it has been positively evaluated by the European Commission, officially starting on January 1st, 2013The project is mainly aimed at demonstrating the feasibility of a pulsed propulsion system1,2 in which the propellants are fed in the combustion chamber at low pressure and the thrust is generated by means of high frequency pulses. The project has been inspired by the defence mechanism against predators of a notable insect: the bombardier beetle.3-5The PulCheR propulsion system concept is intended to mimic the defence mechanism of the bombardier beetle for generating an efficient thrust by high frequency pulses, borrowing by nature the concepts of low pressure feeding of propellants, quasi-constant volume combustion and high frequency pulses. The PulCheR thruster operation relies on the unsteady combustion for generating high pressure peaks inside the combustion chamber that allow for increasing the combustion temperatures (as a result of the quasi-constant volume combustion) and the performance of the thruster always operating in pulse mode. The radical innovation introduced by this concept is the elimination of any external pressurizing system even if the thruster works at high pressure inside the combustion chamber. At each pulse, pressurization of the combustion chamber gases takes place due to the decomposition or combustion reaction, and the final pressure is much higher than the one at which the propellants are stored. The weight of the feeding system is significantly reduced because the propellants are fed at low pressure and there is no need for turbopumps, high pressure propellant tanks or gas vessels. The feed pressure becomes independent on the chamber pressure and the performance degradation typical of the blowdown mode in monopropellant thrusters can be avoided. The pulsed chemical rocket concept is potentially able to substitute many currently used propulsion systems for in space applications. It can be employed for low orbital flight and beyond and subsequent re-entry (allowing also for re-usable vehicles), and can be used in space vehicles for typical manoeuvres around a planet or during interplanetary missions. Since the beginning of 2013, the PulCheR Consortium has been investigating the feasibility of this new propulsion concept at breadboard level in both mono and bipropellant configurations through the design, realization and testing of a platform of the overall propulsion system including all its main components. In addition, the selected green propellants6-8 (High Test Peroxide and methylacetilene) have similar propulsive performance to the current state-of-the-art for monopropellant and bipropellant thrusters. The final test campaign will experimentally investigate the propulsive performance of the system in terms of specific impulse, minimum impulse bit and thrust modulation. The present paper aims at presenting an overview of the main results of the activities performed int he second year of the project and its current status.