RT Journal Article ID 34df612e054ae4be A1 Inoue, Chihiro A1 Fujii, Go A1 Daimon, Yu T1 MIXING LENGTH SCALE OF BI-PROPELLANT THRUSTERS FOR CHARACTERISTIC VELOCITY FORMULATION JF International Journal of Energetic Materials and Chemical Propulsion JO IJEMCP YR 2017 FD 2018-05-08 VO 16 IS 3 SP 281 OP 294 K1 bi-propellant thruster K1 hypergolic propellant K1 impinging injector K1 characteristic velocity K1 theoretical analysis K1 mixing model K1 experimental analysis AB Bi-propellant thrusters in space propulsion systems often utilize unlike-doublet or triplet injectors as the hypergolic propellant injection device. The impingement of liquid jet streams of fuel and oxidizer involves sheet expansion, droplet fragmentation, mixing, evaporation, and chemical reactions in liquid and gas phases. In the sequential reactive, multiphase, thermo-fluid dynamics, the rate controlling phenomenon is the mixing step. In this study, a defined length scale demonstrates the distribution of fuel and oxidizer and thus represents their mixing states, facilitating the straightforward formulation of characteristic velocity in a consistent manner for doublet and triplet injectors as a function of propellant injection conditions with a film cooling effect. The validity of the present modeling framework is confirmed by a good agreement with characteristic velocity measured by hot firing tests covering a wide range of the mixture ratio. We also clarify the meaning of a widely accepted practical indicator, the so-called Rupe factor, over half a century of injector design history. PB Begell House LK https://www.dl.begellhouse.com/journals/17bbb47e377ce023,42e4be8c4549d82d,34df612e054ae4be.html