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Proposing Institution

Lehrstuhl für Aerodynamik, TU München
Project Manager

PD Dr.-Ing. habil. Christian Stemmer
Boltzmannstr. 15
85748 Garching
Abstract
Many of todays fluid flow devices are operated at high pressures, at which the fluid properties significantly deviate from those of an ideal gas. Examples for high-pressure applications are, for instance, liquid rocket engines and high- pressure Diesel engines, in which modern devices aim at further increasing the chamber pressure. Typical injection pressures are in the order of 10 MPa exceeding the critical pressure of common propellants such as hydrogen, oxygen and most hydrocarbons. At the same time, the oxidizer injection temperatures in liquid rocket engines can be cryogenic, at approximately 85 K, while Diesel motors typically work at fuel injection temperatures of approximately 350 K. Further examples for high-pressure applications are cooling channels of liquid rocket engines, as well as stationary gas turbines that are operated as an organic Rankine cycle. The design process of all these devices increasingly relies on computational fluid dynamics (CFD) simulations. Within the collaborative research program “Transregio 40”, one objective is to develop high-fidelity numerical tools for an optimized design process for modern high performance Liquid Rocket Engines (LRE). Numerical simulations at high pressure / low temperature conditions face considerable challenges with regard to modeling accuracy and computational efficiency. This is primarily due to the drastic changes of fluid properties close to the pseudoboiling line, which describes the supercritical liquid-like to gas-like transition. For instance, density, viscosity, and specific heats become strongly non-linear functions of pressure and temperature and complex transport models and equations of state (EOS) are needed for meaningful CFD simulations at near-critical conditions. For our studies we have developed a real gas thermodynamics framework within our in-house large-eddy simulation (LES) code INCA. As an highly demanding application example we simulate the coaxial injection of cryogenic nitrogen and warm hydrogen into a supercritical nitrogen atmosphere. Preliminary simulation results and detailed analyses of thermodynamic aspects highlighted many aspects we would like to address by additional simulations. Some of our most recent results have already been presented at the “Ninth International Symposium on Turbulence and Shear Flow Phenomena (2015)”, and the applicants are confident that future results of this investigation will be published in a peer-reviewed journal.

Impressum, Conny Wendler