Numerical Investigation of Turbulent Combustion during Line Heating Process

本研究的目的是发展一种在管道加热过程中从加热气体到板的热量传递的数值研究方法。提出了一种新的修正涡流耗散燃烧模型。通过对现场加热过程中气体温度的计算值和实测值的比较，验证了该模型的有效性。用LIF仪测量了氧-甲烷气体火焰的瞬态温度分布。对点加热和线加热过程中温度场的变化性质进行了细致的研究。研究了低雷诺数k-ε湍流模型的有效性。结果表明：1)从L.I.F.测量结果来看，火炬周围气体温度的相对分布与现场加热时几乎相同。还发现，这种相对分布几乎没有变化，而不考虑温度的升高。2)以上结果使我们提出了一个新的假设，即在管道加热过程中，火炬周围气体温度和局部换热系数的相对分布保持不变，与现场加热时基本相同。基于这一假设，提出了一种新的线加热过程的热输入估计方法，该方法可以仅从点加热实验结果中获得所需板形、尺寸和火炬运动历史的板温分布历史。3)采用改进的涡流耗散燃烧模型，计算得到的现场加热过程中的气体温度分布与实测值吻合较好。该模型适用于管线加热过程中冲击射流火焰的分析。4)采用低雷诺数k-e湍流模型的计算结果表明，板表面邻近区域的热流受湍流影响较大。这表明采用低雷诺数k-e湍流模型可以提高湍流边界层内气体温度和传热计算的精度。少

The aim of this study is to develop a method of numerical investigation of the heat transmission from the heating gas to the plate during line-heating process.New modified-eddy-dissipation combustion model is proposed. The validity of the proposed model is demonstrated by comparing the calculated and measured gas temperature during spot heating.The transient temperature distribution is measured using a LIF apparatus in oxygen-methane gas flame from a torch moving linearly. The changing nature of temperature field during spot and line heating is investigated closely and carefully.The effectiveness of low-Reynolds number k-ε turbulence model is also investigated.As results, the followings are found ;1) From the result of L.I.F. measurement, it has been found that the relative distribution of gas temperature around the torch is almost the same as that in spot heating. It has also been found that this relative distribution is almost unchanged regardless of the temperature increase in the s … More teel plate.2) The above result leads us to a new hypothesis that the relative distributions of gas temperature and local heat transfer coefficient around the torch remain unchanged and they are almost the same as those in spot heating during line heating process. A new method of heat input estimation for line heating process based on this hypothesis, by which plate temperature distribution history can be accomplished for desired plate shape, dimensions, and torch movement history, solely from spot heating experimental results, has been propounded.3) The calculated gas temperature distribution during spot heating is in good agreement with measured one when proposed modified-eddy-dissipation combustion model is employed. It is preferable to employ the proposed model in analysis of impinging jet flame during line heating process.4) The calculation result in which low-Reynolds number k-e turbulence model is employed shows that heat flow in the immediate neighborhood of the plate surface is greatly affected by turbulent flow. This suggests that the precision of gas temperature and heat transmission calculation within the turbulent boundary layer can be improved by employing low-Reynolds number k-e turbulence model. Less