Validation and development of wall-function models for liquid rocket engine applications

In this work algebraic wall-function models for the prediction of thermo-mechanical loads in rocket-engine applications are explored and investigated. To this end two categories of turbulent wall-bounded flows are identified: a non-premixed flame impinging parallel to an isothermal wall and a cryogenic stream flowing in a heated pipe at high pressure. For the mentioned configurations, reference solutions are used for the sake of validation from experimental and numerical campaigns. For the former configuration, wall-function models from literature are first categorized based on the degree of modelling of the thermal field and then applied to the simulation of a realistic single-injector oxygen/methane rocket chamber. For the latter, an extension of one of the model selected from the previous analysis is proposed in order to deal with real-gas conditions. Results show that while wall-heat-flux predictions are well reproduced by the proposed wall-modeled framework and by algebraic wall-functions as long as the kinematic-thermal coupling is retained, applications of algebraic wall-functions to cryogenic high pressure flows still require further advancements in order to provide reliable predictions of key wall quantities.