Experimental investigation of a low Reynolds number flame jet impinging flat plates

• Published in: International journal of heat and mass transfer 2020-08, Vol.156, p.119856, Article 119856
• Main Authors: Schuhler, Eliot, Lecordier, Bertrand, Yon, Jérôme, Godard, Gilles, Coppalle, Alexis
• Format: Article
• Language: English
• Subjects: Composite materials; Engineering Sciences; Exact solutions; Flat plates; Fluid flow; Heat flux; Heat transfer; High temperature; Impinging jet; PIV; Reactive fluid environment; Reynolds number; Thermal degradation; Thermal stress; Thermocouples; Thermophysical properties; Velocity; Velocity distribution; Wall jets
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2020.119856

•Particle image velocimetry has been used in a non-reacting hot impinging jet.•Pyrolysis gas have little effect on the impinging jet flow.•Viscosity effects are negligible compared to kinetic effects in the studied configuration. A propane burner is used to produce an impinging flame jet onto composite materials in order to understand the thermal degradation of these materials under a high heat flux as a model of reaction to a fire. In the present work, the thermal stress is produced by hot gas exiting from the burner at low Reynolds number and with a short distance between the burner exit and the sample. The temperature, velocity fields and heat fluxes of the impinging jet have been determined experimentally by using thermocouples, the Particle Image Velocity (PIV) technique and a heat flux sensor in order to characterise the thermally stress conditions imposed on the sample. The experimental results are compared to the most valuable analytical solutions found in the literature, in particular Schlichting's theory for the velocity and Sibulkin's and derived relations for the heat transfer to the wall. This allows to better understand what are the main parameters controlling the thermal stress. Most of the analyses have been performed in the stagnation zone and in the wall jet, where the velocity profiles and the heat flux to the wall are well predicted if the thermophysical properties are determined at the hot gas temperatures and low Reynolds number.