内燃机燃烧室壁温度波的理论研究

Theoretical Study on Temperature Fluctuations in the Combustion Chamber Wall of I. C. Engines

本文针对一维瞬态热传导方程,定义了稳态温度、瞬态温度和波动温度等概念,给出了利用线性叠加原理和分离变量法得出的温度波的理论解的形式。再针对内燃机中复杂的第三类边界条件,利用傅立叶分析法、三角形脉冲热流叠加法和辛普森积分法,计算了内燃机燃烧室壁的温度波,并与实测结果进行了比较。然后对温度波的渗透与衰减特性进行了探讨,分析了温度波的渗透与衰减过程中的能量守恒规律,给出了温度波的波长的概念,并指明了温度波的波长是衡量其渗透能力和衰减特性的指标,对温度波的实验研究和数值研究有着重要的指导意义,比所谓渗透深度或瞬变温度层厚度具有更明确的物理意义。

In this paper, some concepts such as steady-state, transient temperature, and fluctuant temperature etc. are defined in terms of one dimension transient heat conduction equation. By the use of the principle of linear superposition and the method of separation of variables, the form of theoretical solution to temperature fluctuations is presented. The paper also, on the basis of Fourier analysis, superposition of triangular heat flux impluse and Simpson integration, makes calculations on the temperature fluctuations in the combustion chamber wall of I. C. engines and compares them with corresponding experimental results. Through discussions on characteristics of penetration and damping, conducted under the principle of energy conservation, the paper proposes the concept of wavelength of temperature fluctuations. According to the paper, the concept of wavelength denotes the characteristics of penetration and damping of temperature fluctuations, being of more significance than the concept of 'penetration distance' or 'thickness of transient temperature layer' in the study of temperature fluctuations experimentally and numerically.