Design and Numerical Analysis of Double-Base Swirl Injector for Ethanol/Hydrogen-Peroxide Based Liquid Propellant Rocket Engine

This paper presents a study of numerical cold flow analysis of double-base swirl injector design using Ansys Fluent. The study focuses on the design validation and development of double-base liquid-liquid swirl injector for Ethanol(Fuel) and Hydrogen Peroxide(Oxidizer) based liquid propellant rocket engine. The green propellant contains 80% Ethanol (C₂H₅OH) as fuel and 60% Hydrogen Peroxide (H₂O₂) as oxidizer. A comprehensive data, obtained from NASA CEARun code, of performance parameters and carbon monoxide and carbon dioxide emission of most commonly used propellant is compared with ethanol and hydrogen-peroxide based propellant is presented for reference. Secondly, the paper presents the theoretical design model of Swirl Injector, and numerical cold flow study of swirl injector model. For this the 3D models of fuel and oxidizer swirl nozzles are designed separately as per the theoretical design parameters. Poly-hexacore type fluent meshing is used to generate valid mesh. A 3-D, Steady State, Pressure based, SST k-omega Turbulence model is used to carry out the cold-flow simulations. The CFD simulations are carried out separately for oxidizer and fuel nozzles and finally combined model is used for final analysis. Also, this paper presents the study of effects of varying contraction angle (α = 50 °, 55 °, 60°) of the swirl chamber and outlet orifice diameter (d_o = 3.4, 3.6. 3.8 mm) in swirl injector(oxidizer nozzle) using 9 different models. It was found that increasing or decreasing the contraction angle of the swirl chamber results in narrower and wider spray cone angle and also increment and decrement in mass flow rate of the fluid respectively. The final result of this comparative study concluded that nozzle with α = 55 ° and D_o = 3.4mm gave the best result out of the 9 different geometric parameters. The theoretical design mass flow rate of fuel and oxidizer is obtained and validated numerically at design pressure drop value of 1.5 bar for both the fuel and the oxidizer nozzle. The post-processing analysis results are presented in the form of contours, streamlines and comparative graphs. The theoretical design model of the swirl injector is validated successfully through numerical analysis of the swirl injector model. Further, this swirl injector model can be developed to carryout experimental tests and validation.