一种新型双层热感式微流量传感器及参数优化

热感式微流量传感器具备灵敏度高、可靠性好、测量精度高等优势，广泛应用于环境监测系统、生物研究、化工工艺控制等领域，然而传统热感式流量传感器的量程有限，从而限制了其进一步拓展应用领域。本文提出了一种新的设有主次双流道的双层热感式微流量传感器，低流率时输出主流道的温差信号，而大流率时输出次流道的温差信号，从而拓宽量程。为了能获得更好的传感器性能，通过数值模拟优化了支流流道入口大小与位置和流道高度与宽度，优化后双层热感式微流量传感器的量程为0～145 m/s式，同时确保灵敏度超过0.03 K/(m·s^-1),并且确定了主次流道输出温差信号的转换流速阈值为63 m/s。最后分析了传感器内部粘性耗散，发现上游探测器前端的粘性耗散是引起传感器失效的主要原因，为改进热感式微流量传感器性能提供参考。

Novel double-layer thermal microflow sensor and preferential parameters

Due to the advantages of high sensitivity, reliable performance and high measurement accuracy, the thermal microflow sensors are widely used in various fields, such as environment monitoring systems, biological research, process control chemical engineering, and so on. However, the limited range of such sensor impedes the extension of application fields. In this article, a new double-layer and two-channel thermal microflow sensor is proposed for wider measure range. The temperature-difference output is from the sensor in mainchannel at low flowrate, from that in side-channel at high flowrate. To improve the performance of microflow sensor, simulations are conducted to obtain the preferential parameters, such as the size and position of inlet for side-channel, as well as the height and width of main-channel and side-channel. The measure range of improved microflow sensor is 0~ 145 m/ s when the sensitivity being greater than 0. 03 K/ (m·s -1 ). The switching threshold of inlet velocity for temperature-difference output from the main-channel to side-channel is 63 m/ s. Finally, the viscous dissipation of in the microflow sensor is analyzed and found, the viscous dissipation at the front-end of the upstream detector is the main cause of the failure of microflow sensor. This can provide an effective method for improving the performance of the thermal microflow sensor.