The effect of the thermal prong—wire interaction on the response of a cold wire in gaseous flows (air, argon and helium)
The effect of the thermal prong—wire interaction on the response of a cold wire in gaseous flows (air, argon and helium)
复制标题
热插脚与金属丝相互作用对冷金属丝在气流（空气、氩气和氦气）中的响应的影响
DOI：
10.1017/s0022112082002584
复制
发表时间：
1982
影响因子：
3.7
通讯作者：
J. Lecordier
中科院分区：
文献类型：
--
作者：
P. Paranthoen;C. Petit;J. Lecordier
本文研究了用作热传感器的冷丝在湍流中对不同类型探头和多种气体（空气、氩气和氦气）的响应。现在众所周知，正如 Perry、Smits 和 Chong (1979) 所指出的，在空气流动的情况下，探头的传递函数在低频处显示出典型的阶跃。在此平台区域中，线温度可能会通过两个不同的路径受到插脚温度的影响。第一个是插脚和导线之间的传导，正如 Maye (1970) 已经使用 Betchov (1948) 引入的“冷长度”lc 所讨论的那样。正如 Hojstrup、Rasmussen 和 Larsen (1975) 所建议的，第二个原因是在大热扩散系数的气体中低速时，叉头上的热边界层非常大；该影响区域（由插脚）延伸到以插脚上的热边界层的厚度lb为特征的导线长度上。本文通过引入参数 η = lb/lc，对考虑这两种效应的冷丝传递函数的行为进行了简单分析。已经使用一种程序对这些现象进行了实验研究，该程序允许在比目前通常采用的频率范围更大的频率范围内产生温度波动。使用此分析对不同气流（空气、氩气和氦气）中的几种类型的插脚进行分析，实验结果与预测之间取得了良好的一致性。由于氦气的热扩散率较大，在后一种情况下发现了频率响应的一个重要步骤。此外，在间歇温度测量的简易性中还提供了热插脚与导线相互作用的示例。
This paper deals with the study of the response of a cold wire used as a thermal sensor in a turbulent flow for different types of probes and for several gases (air, argon and helium). It is now well known that in the case of air flows the transfer function of the probe shows a typical step at low frequencies, as pointed out by Perry, Smits & Chong (1979). In this plateau region the wire temperature may be influenced by the prong temperature through two different paths. The first is conduction between prong and wire, as already discussed by Maye (1970) using the ‘cold length’ lc, introduced by Betchov (1948). As suggested by Hojstrup, Rasmussen & Larsen (1975) the second is the result of the thermal boundary layer on the prong being very large at low velocities in gases of large thermal diffusivity; this region of influence (by the prong) extends over a length of the wire characterized by the thickness lb, of the thermal boundary layer on the prong. In this paper a simple analysis of the behaviour of the transfer function of cold wires taking these two effects into account is presented by introducing the parameter η = lb/lc. An experimental investigation of these phenomena has been undertaken using a procedure which allows temperature fluctuations to be produced over a larger range of frequencies than has been usually made up to now. Good agreement is obtained between experimental results and predictions using this analysis for several types of prong in different gaseous flows (air, argon and helium). An important step in the frequency response is found in the latter case because of the large thermal diffusivity of helium. Furthermore an example of the thermal prong–wire interaction is presented in the ease of intermittent temperature measurements.