Study on Heat Transfer Phenomena between the Combustion Flow Field and the Heating Plate during Line Heating Process (2nd Report)

Abstract

In order to automate line heating process, heat transfer between flame and plate has to be evaluated theoretically. This evaluation becomes possible when we can estimate the temperature distribution of the heating gas near the plate surface and the distribution of the local heat transfer coefficient.The authors showed that the temperature distribution near the plate could be estimated by calculating the heat flow of non-combustion impinging jet in place of the combustion flame. In this approach, it is needed to give the temperature, velocity of the virtual non-combustion gas at the nozzle exit and the width of the jet at the exit as the calculation conditions. For 2-dimensional gas flame, close agreement between measured and calculated temperature near the plate surface was obtained when the highest temperature within the flame, the velocity of gas mixture at the upstream side of the nozzle and the width of the actual combustion flame was employed as the temperature, velocity and width of the virtual gas at the exit.The gas flame used in the actual line heating process is 3-dimensional. So, it is needed to measure the transient temperature distribution of 3-dimensional gas flame near the plate surface accurately. Such measurement can be performed by laser iduced fluorescence (L. I. F.) technique.In this paper, for 3--dimensional axial symmetry jet, the transient temperature distribution near the plate surface in the spot heating gas flame is measured in detail by a high-performance L. I. F. measurement system. The temperature in this case is also calculated by the numerical method proposed in the previous paper. Comparing the calculated and experimental results, the tendency of the temperature distribution is discussed in the case where the proposed method is applied to 3-dimentional cases.