Coupled Heat Transfer Analysis in Regeneratively Cooled Thrust Chambers

A computational procedure able to describe the coupled hot-gas/wall/coolant environment that occurs in most liquid rocket engines and to provide a quick and reliable prediction of thrust-chamber wall temperature and heat flux as well as coolant-flow characteristics, like pressure drop and temperature gain in the regenerative circuit is presented and demonstrated. The coupled analysis is performed by means of an accurate CFD solver of the Reynolds-Averaged Navier-Stokes equations for the hot-gas flow and a simplified quasi-2D approach, which widely relies on semi-empirical relations, to study the problem of coolant flow and wall structure heat transfer in the cooling channels. Coupled computations of the Space Shuttle Main Engine Main Combustion Chamber are performed and compared with available literature data. Results show a reasonable agreement in terms of coolant pressure drop and temperature gain with nominal data, whereas the computed wall temperature peak is quite closer to hot-firing data than to the nominal value. © 2012 by B. Betti, M. Pizzarelli, F. Nasuti

Experimental and Numerical Investigations of Thermal Stratification Effects

In the frame of this work, thermal stratification effects withincooling channel flow of hydrogen cooled combustion chambers are investigated with theoretical approaches. Experimental results with a hydrogen cooled cylindrical combustion chamber segment with four different cooling channel geometries are presented. A new stratification approach that consideres the limited mixing capabilities within the turbulent core flow of the cooling channel is validated with the help of the experimental results

Analysis of Curved-Cooling-Channel Flow and Heat Transfer in Rocket Engines

Coolant-flow modeling in regeneratively cooled rocket engines fed with turbomachinery is a challenging task because of the high wall-temperature gradient, the high Reynolds number, the high aspect ratio of the channel cross section, and the curved geometry. In the present study, to better comprehend the role of the thrust-chamber shape of a rocket engine on the heat exchange, computations of supercritical hydrogen flow in single- and double-curvature channels are carried out. In particular, a parametric numerical analysis of the flow in an asymmetrically heated rectangular channel with a high aspect ratio and various radii of curvature is performed by means of a Reynolds. averaged Navier Stokes solver for real fluids, which is validated against experimental data of heated and curved. channel flow taken from open literature. Results permit the effect of curvature on global heat transfer coefficient, pressure loss, and bulk temperature increase to be quantified

Analysis on the effect of channel aspect ratio on rocket thermal behavior

A trade-off analysis is performed on a test case representative of the cooling system of 1 MN thrust class oxygen/hydrogen liquid rocket engine. The aim of the analysis is to find the channel aspect ratio that maximizes the heat extracted from the hot-gas, for a given coolant pressure drop and hot-gas side wall temperature. The analysis requires many cooling channel flow calculations which are performed by means of a simplified model, referred to as quasi-2D, and an accurate conjugate heat transfer model based on numerical integration of the Navier-Stokes and Fourier's Equations. Both models are able to describe the whole cooling device composed by the coolant and the solid domain, which is exposed the hot-gas, with different computational time and level of details. The fast quasi-2D approach is used to select channel geometries showing the same pressure loss. Discussion is made on results obtained with the more accurate CHT model. Results identify, for the selected test case, an ideal aspect ratio which optimizes cooling performance at large values of channel aspect ratio © 2012 by M. Pizzarelli, F. Nasuti, M. Onofri