3 Numerical Analysis of the Thermophysical Characteristic of Multiphase Flow of Liquid Hydrogen Through Feed Pipe of Rocket Engine Kanak Raj and L. Prince Raj Abstract Analysing the two-phase flow behaviour of cryogenic propellants like LH 2 -VH 2 and the accompanying flow regime utilizing volume fraction is made easier by the current analysis. Additionally, two phases of liquid hydrogen (LH 2 ) in different inlet velocities and tem- peratures have been described in the current work. With the aid of the commercial CFD program Ansys Fluent, a two-dimensional computer model of a cryogenic feed line, has been created for the present study. To character- ize the two-phase flow of LH 2 and to accurately estimate hydrodynamic and thermodynamic properties under various situations, the volume of fluid (VOF) approach based on an Eulerian flow scheme incorporated with an energy equation is used. These models have been vali- dated with experimental data, and the trend of volume fraction captured matches the computational result. The flow visualization and the volume fraction has evalu- ated along with bulk mean temperature (Tb) and veloc- ity analysis. Therefore, the current methodology may be used to estimate the flow shape and phase distribution at different initial conditions. Keywords Multiphase · VOF · Heat Transfer · CFD 1 Introduction The space industry has witnessed a growing push over the past ten years to create more affordable, commercially based access to space, and a significant drop in the cost per kilogram of cargo to orbit has already been attained. Thus, for the deep mission, space industries are expanding towards liquid propellants as fuel in rocket engines due to their high specific impulse (Sutton and Biblarz 2016). This has been made possible in part by purposeful complex- ity reductions and/or an enhancement in the reusability of launch vehicles. Liquid rocket engines are widely used in reusable launch vehicles due to their high specific impulse (Meyer et al. 2012). Like most liquid propellant rocket engine, liquid hydro- gen (LH 2 )/liquid oxygen (LO 2 ) is fuel, where LH 2 is stored in a storage tank below 20 °C (boiling point). The fuel has transferred from the storage tank to the combustion cham- ber through the transfer feed pipe which is insulated over the circumference of the pipe. As no material is perfectly insulated, heat transfer from the ambient to the feed pipe occurs. Thus, it results in the LH 2 boiling into vapour, caus- ing two-phase flow phenomena (Notardonato 2012). Multiphase phenomena have been extensively stud- ied over the past few decades. Advances in instruments, sensors, and image processing devices have attracted researchers toward experimental studies (Xie et al. 2017, 2017; Hartwig et al. 2015; Yuan et al. 2007), while a few computational works has been also seen in these areas (Yuan et al. 2008, 2009; Takamasa et al. 2003; Ghorai and Nigam 2006; Kharangate and Mudawar 2017; Duan et al. 2023). In order to control cryogenic fluid in space, Kawanami et al. 2007 studied cryogenic forced convective boiling in both terrestrial and microgravity environments. They observed that heat transfer increased in the pres- ence of microgravity in their studies, which were aimed at determining the impact of gravitational acceleration on flow behaviour and thermal properties. Very few of the © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025 R. Mukesh et al. (eds.), Proceedings of the 1st International Conference on Advances in Aerospace and Navigation Systems—2024, Advances in Science, Technology & Innovation, https://doi.org/10.1007/978-3-031-76937-5_1 K. Raj · L. Prince Raj (*) Aerospace Engineering and Applied Mechanics Department, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, India e-mail: plraj@aero.iiests.ac.in