Feasibility analysis of lab-scale electric heater for ram-air supply in ducted-rocket combustor

Currently, the development of more fuel-efficient engine cycles for the ascent to orbit for the access to space is undergoing. Combination Propulsion System (CPM) is deemed as a solution and is characterized by the use of two or more separate propulsion systems operating independently. The combination of a rocket booster and a ramjet engine is a typical example. Ducted-Rockets/Air-augmented is an integration of solid rocket motor (gas generator) and ramjet system. It takes advantage of both solid rockets and the long flight capability of air-breathing engines. The availability of the oxidizer from the atmosphere allows the system to reduce the oxidizer content in the propellant. Such oxidizer deficiency in the propellant contributes to the increment of the specific impulse of the propulsion system, rendering it one of very attracting features of this system. In this work, the design of a lab-scale heater to generate the ram-air is carried out, which will serve for the analyses of the combustion process in the second combustor of Ducted-rockets. In the aim of avoiding the contamination of the ram-air, non-combustion heater was selected as a starting point. The system is composed of a cylindrical furnace with a duct inside and metal wires for joule heating. Due to the very high temperature in the heater, along with the heat transfer analyses, careful considerations were also applied on the mechanical properties of the materials. To compensate some approximations applied in the preliminary design process and to refine the design, a numerical simulation with COMSOL Multiphysics was also carried out. All of these works were executed in Space Propulsion Laboratory (SPLab), Department of Aerospace Science Technology, Politecnico di Milano.