基于热传递过程的薄层水流流速测量方法及装置

基于薄层水流中的热传递过程，提出测量水流流速的示踪方法，并设计对应的测量系统。在室内试验坡面上，设计不同试验工况(坡度为5°,10°,20°,流量为2,5,8 L/min),以盐示踪法为对照，研究热示踪测量薄层水流流速的可行性及其影响因素。结果表明，测量系统能准确地测得热示踪剂的运移过程；热与盐2种示踪剂测得流速范围为0.408～1.522 m/s,线性拟合斜率为1.006,R²为0.993,表明两者具有显著的线性关系，热示踪法具有较高的可靠性；由于物理属性差异，部分水力工况下示踪剂的释放方式对盐和热的测量结果影响显著，表明此时2种示踪剂测量流速的代表性不同；可采用盐与热联合示踪的方法，取二者测量结果的均值作为薄层水流的平均流速，以提高测量结果的代表性。研究结果可为复杂下垫面、盐渍化和禁用化学成分等特殊坡面上薄层水流流速的准确测量提供新方法和理论参考。薄层水流流速的准确测量对地表水文和土壤侵蚀领域的研究具有重要意义。

A Method and Instrument for Measurement of Sheet Flow Velocity Based on the Heat Transport Processes

Based on the heat transfer process in thin water streams, a tracer method was proposed to measure the flow velocity of water streams and a corresponding measurement system was designed. Different test conditions (5°, 10° and 20° slope, 2, 5 and 8 L/min flow rate) were designed on an indoor test slope to investigate the feasibility of the heat tracer measurement of thin water flow velocity and its influencing factors, using the salt tracer method as a control. The results showed that the proposed system measured the transport processes of the thermal tracer accurately and the flow velocities calculated basing on the thermal transport processes had a significant linear relationship with that by the salt tracer. The measured velocities ranged from 0.408 to 1.522 m/s with high accuracy, and the flow velocity by thermal tracer was 1.006 times of the salt tracer with the R² of 0.993, which indicted the high reliability of the thermal tracing method. As affected by the tracer physical properties, the release mode had a significant effect on the measurement of sheet flow velocities under some hydraulic conditions, and it indicted that the velocities measured by salt and thermal tracer represented velocity of distinct layers of the flow. By using the combined salt-thermal tracer, the average of velocities by thermal and salt tracer can be taken as the velocity of the sheet flow, to improve the representativeness of the measurements under certain hydraulic conditions. The results of the study provided an alternative method for the accurate measurement of sheet flow velocities on slopes with complex underlying surface and high salt content, or under conditions of chemical free. Accurate measurement of thin flow velocities is of great importance for understanding in the field of surface hydrology and soil erosion.