Determination of Effective Recombination Probability: Detailed Aspects of a Macroscopic Methodology

摘要

The purpose of the present Lecture Series is to provide an up-to- date review of the experimental techniques, the theoretical models, as well as the numerical simulation strategies involved in the treatment of the chemical character of high temperatures gases. To this end, aspects of both materials and high temperatures uid sciences are discussed together, with the aim of enhancing the improvements in the understanding of the processes of heat release on solid surfaces close to reactive gases taking place in re-usable hypersonic light vehicles, ballistic missiles, and rockets exhaust nozzles. In addition, further details are given concerning the modeling and the experimental investigation of gas-surface interactions. This latter aspect is strongly related to the diffusive component of the heat ux experienced by a vehicle entering the atmosphere. In particular, the way in which the Thermal Protection Material (TPM) influences the gas particle recombination on its surface has a tremendous effect on the wall heat flux. As will be shown later on, the heat flux measured in the stagnation point of a probe held in a plasma wind tunnel can simply double when materials enhancing complete recombination are used instead of inert material. Therefore, the role played by the modelling of gas/surface interactions is of fundamental importance in the understanding of heat-transfer and as a consequence in the design of Thermal Protection Systems (TPS). When analyzing the interaction between a gas and a non ablating surface, at least two approaches can be put in evidence. A microscopic and a macroscopic approach.