微小荧光测温探头热响应过程非稳态传热特性分析

The transient heat transfer characteristics analysis of the thermal response in a mini probe covered with fluorescent coating

荧光测温是一种高灵敏度的光致光学测温方法,可用于测量温度动态变化。但荧光涂层低导热率的特点,可能会改变荧光涂覆物体(如测量探头)的非稳态传热特性,进而影响热响应过程的测量精度。针对微小荧光测温探头的热响应过程,该文采用理论分析和数值计算相结合的方法研究探头随主流流体温度变化的非稳态传热特性。研究结果表明,探头荧光涂层的热响应时间不仅受外表面对流换热条件的影响,同时受到探头基座导热热阻的影响。涂层温度达到稳定状态需要基座也基本达到稳定状态。当采用高导热材料时,探头内部基座的热响应速率随荧光涂层厚度的变化不明显。

Fluorescence is a highly sensitive photoluminescence optical temperature measurement method,that can be used to measure the temperature dynamic change.However,the low thermal conductivity of the fluorescent coating may change the transient heat transfer characteristics of the fluorescent coated object(such as the probe),thereby affecting the measurement accuracy of the thermal response process.In order to analysis the thermal response process of the mini probe covered with the fluorescent coating,this paper uses a combination of theoretical analysis and numerical calculation to study the transient heat transfer characteristics of the probe in a mainstream field with temperature changes.It is showed that,the thermal response time of the fluorescent coating and the mini probe is not only affected by the convective heat transfer characteristics of the outer surface,but also affected by the thermal resistance of the probe base.Before the coating temperature reaches a stable state,the base must basically reach a stable state.If the probe base is the high thermal conductivity material,the thermal response rate does not change significantly with the thickness of the fluorescent coating.