Assessment of Analytical Models for Film Cooling in a Hydrocarbon/GOX Rocket Combustion Chamber

Abstract

The understanding of the mechanisms of heat transfer and advanced cooling techniques is a key for mastering the designing of reliable and efficient rocket combustion chambers. However, the effects determining film cooling efficiency as well as influences on the combustion process itself under typical conditions for rocket engines are still insufficiently understood. Therefore, the Institute for Flight Propulsion (LFA) of the Technische Universität München operates a rocket combustor test facility which allows testing at application-relevant conditions. The experimental work is complemented by numerical investigations, where in day-to-day operations also analytical and semi-empirical correlations are used. This paper presents an assessment of different analytical and semiempirical film cooling models known from open literature and their application to kerosene film cooling in a GOX/ kerosene combustion chamber. Nomenclature AcronymsCC = Combustion chamber CFD = Computational Fluid Dynamics GOX = Gaseous oxygen MR = Mixture ratio (here oxygen/kerosene mass flow ratio) NHFR = Net Heat Flux Reduction (cooling effectiveness) THERMTEST = Tool for thermal simulation of rocket combustion chamber by TUM Greek Letters  = heat transfer coefficient  = adiabatic film cooling effectiveness,     c cool c aw T T T x T x      = film part, relative film mass flow,  Injector , Kerosene Film Film m m / m       Latin Letters Indices m  = mass flow rate aw = adiabatic wall p = pressure c = chamber, core stream T = temperature cool = coolant (esp. film) O/F = mixture ratio e = entrainment r = radius inj = injector s = slot height t = total x = distance from film applicator throat = regarding nozzle throat

Injector characterization for a gaseous oxygen-methane single element combustion chamber

“…The need for a reliable prediction of the thermal behavior of the institute£s rocket combustion chambers has led to the development of the engineering tool Thermtest at TUM [10]. Thermtest allows the simulation of steady as well as transient thermal behavior of cooled or uncooled structures over a wide scope of chamber materials and cooling §uids.…”

“…Given these justi¦cations, the e¨ort has been initiated to experimentally document the detailed wall heat §ux characteristic of a GOx/GCH 4 shear coaxial single-element injector over a range of pressures and mixture ratios. Additionally, the wall heat §ux results were used as a test case for the validation of the in-house engineering tool Thermtest [10] and to determine the feasibility of LES as a tool at the Georgia Institute of Technology for the analysis of the §ame structure and §ow features [11].…”

Experimental and Numerical Investigation of a Multi-Injector GOX-GCH4 Combustion Chamber

“…Additionally, the test data are used as a test case for the validation of the in-house engineering tool Thermtest. 9) Results of the wall heat flux distribution as well as the comparison with the test data are presented.…”