Hanging the head can avoid damaging the head propeller. When the water current acts on the sensing element of the instrument-the blade, the blade will rotate. The faster the water flows, the faster the blades rotate. There is a certain functional relationship between rotational speed and flow, that is, v=f(n). Therefore, in order to determine the flow rate of water, it is actually only necessary to accurately measure the number of revolutions of the instrument blades and the corresponding time.

Assuming that the critical speed of the instrument is vk, the experiment shows that from below vk to the initial speed v0, the function is in the form of curve, and the relationship above vk is linear. The verification result of each instrument is attached with a chart and the following verification formula: v = bn+a, where: v- velocity (m/s); N—— blade rotation speed (rotation speed), which is equal to the total number of blades "n"; B—— hydraulic pitch (corresponding to the original standard K), in meters (m); A—— instrument constant (corresponding to C of the original standard), m/s alone.

Propeller anemometer

Propeller-type current meter is used to measure the time average velocity of predetermined measuring points in running water. The instrument has the characteristics of small volume, light weight, compact and precise structure, and easy to carry and use. Suitable for shoals, irrigation and drainage canals, water conservancy investigation, runoff test, etc. , widely used in efficiency testing of small and medium-sized pumping stations and efficiency experiments of hydraulic machinery, as well as sewage monitoring and seepage measurement of environmental protection departments.