Abstract
The present work focuses on the development of new mathematical and numerical tools to deal with wave propagation problems in a realistic liquid rocket chamber environment. A simplified real fluid equation of state is here derived, starting from the literature. An approximate Riemann solver is then specifically derived for the selected conservation laws and primitive variables. Both the new equation of state and the new Riemann solver are embedded into an in-house one-dimensional CFD solver. The verification and validation of the new code against wave propagation problems are then performed, showing good behavior. Although such problems might be of interest for different applications, the present study is specifically oriented to the low order modeling of high-frequency combustion instability in liquid-propellant rocket engines.
Highlights
Combustion Chamber Conditions.Recent studies have provided evidence on how the injector elements of liquid rocket engines play a central role in the thermo, hydro, and gas-dynamic coupling that takes place during high frequency combustion instability [1,2,3]
As expected, propagation tests and plain equation of state (EoS) results differ from refprop to the same extent, due to the error introduced by the cubic formulation
A novel thermodynamic modeling approach is derived for dealing with wave propagation in liquid rocket thrust chambers
Summary
Since the intensity of the pressure waves during thermo-acoustic oscillations can be strong, pressure waves coming from the chamber and traveling upstream in the injector can significantly slow the flow down In such a case, vortexes may form, trapping pockets of fresh propellant, which struggle to flow downstream, causing an accumulation process to take place at the recess location. This work is mainly focused on acoustic phenomena and their correct modeling In this sense, attention has to be paid to two major sub-models, namely, the real fluid mixture equation of state (EoS) and the proper numerical approach. A further complication is to assume a cubic model cast for the entire mixture In such a way, mixing is performed by means of species interaction indexes within the EoS [6,7,8]. EoS and RS models are embedded into a one-dimensional Eulerian solver, and they are validated together against wave propagation in real fluids and in real fluid mixtures
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