Measuring water velocity by an ultrasonic method

IT IS DESIRABLE that the water discharged through the turbine of a hydroelectric unit be measured accurately under various conditions of loading, so that basic data may be obtained which will permit operating the unit at all times to extract the maximum power from the available water. There are numerous low-head hydroelectric developments which have short intake conduits carrying large quantities of water to the turbines. There is need for an improved method of measuring the water discharged through units in such stations because the precision of some existing and accepted methods is impaired by an intake of short length and some of the methods require the installation of equipment whose cost is often prohibitive. Further, some of the methods can measure turbine discharge only under special conditions which interfere with normal operation of the plant. Turbulence is sometimes another source of difficulty.