Transient heating of a semitransparent spherical body immersed into a gas with inhomogeneous temperature distribution
Transient heating of a semitransparent spherical body immersed into a gas with inhomogeneous temperature distribution
复制标题
浸入温度分布不均匀气体中的半透明球体的瞬态加热
DOI：
10.1016/j.ijthermalsci.2011.02.012
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发表时间：
2011
影响因子：
4.5
通讯作者：
M. Heikal
中科院分区：
文献类型：
--
作者：
S. Sazhin;I. Gusev;P. Krutitskii;M. Heikal
瞬态热传导方程，描述加热的物体浸入气体中的非均匀温度分布，解析求解，假设在一定的距离，从身体的气体温度保持恒定。这个问题是一个概括的问题解决较早的气体，其中的身体是浸入，被假定为最初是均匀的。该解决方案适用于当气体温度的分布被选择为使得气体中的热通量最初不依赖于在靠近该表面的区域中距物体表面的距离时的情况。该解决方案适用于模拟身体加热的条件接近柴油发动机中观察到的。指出气体温度分布的不均匀性会导致物体加热速度的减慢。在较长的时间范围内，物体和气体的温度分布不依赖于气体温度的初始分布。在一个身体浸入到一个不均匀的气体的情况下，对于大的时间牛顿定律的校正被证明是基本上相同的预测模型，基于气体最初是均匀的假设。在短时间内，这种校正接近有限值，远低于模型预测的值，基于气体最初是均匀的假设。对于大的气体区域，这些值接近于1。这些结果基本上证实了早先的发现，即忽略这些修正预计会导致计算中不可接受的大误差。
The transient heat conduction equation, describing heating of a body immersed into gas with inhomogeneous temperature distribution, is solved analytically, assuming that at a certain distance from the body gas temperature remains constant. This problem is a generalisation of the problem solved earlier where gas, into which the body is immersed, was assumed to be initially homogeneous. This solution is applied to the case when the distribution of gas temperature is chosen such that heat flux in gas initially does not depend on the distance from the body surface in the region close to this surface. The solution is applied to modelling body heating in conditions close to those observed in Diesel engines. It is pointed out that inhomogeneous gas temperature distribution leads to slowing down of body heating compared with the case when the body is immersed into a homogeneous gas. In a long time limit, the distribution of temperature in the body and gas does not depend on the initial distribution of gas temperature. In the case of a body immersed into an inhomogeneous gas, for large times the correction to the Newton law is shown to be essentially the same as predicted by the model, based on the assumption that gas is initially homogeneous. For short times, this correction approaches finite values, well below those predicted by the model, based on the assumption that gas is initially homogeneous. For large gas domains these values are close to 1. These results essentially confirm the earlier finding that ignoring these corrections is expected to lead to unacceptably large errors in computations.