Some experiences on flow rate measurements in hydropower plants using the pressure-time method

摘要

One of the most difficult tasks in the performance tests of hydraulic machines (turbines and pumps) is related to measuring the flow rate (discharge). Particularly, this problem concerns the large-size structures, which can be found in hydropower plants. In this case, flow rate measurement is difficult and expensive because of the lack of relevant devices assuring sufficient accuracy. Only a few special methods giving satisfactory accuracy are available under the conditions occurring in hydropower plants. This paper deals with the pressure-time method (sometimes called Gibson method) as one of the principal methods of flow rate measurement in large-scale hydraulic machinery. The paper concerns some experiences on flow rate measurements carried out by means of the pressure-time method gathered during tests performed in many hydropower plants. Presented issues are related to instrumentation, measurement methodology and computation of the flow rate based on the recorded time course of pressure difference changes between two hydrometric sections of the penstock. The issues raised in the article contribute to broaden the applicability of the method and to improve its accuracy.