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Discharge measurement and performance tests of hydraulic units in low-head small hydropower installations

Steller J., Adamkowski A., Henke A., Janicki W., Kaniecki M., Krzemianowski Z.

Transactions of the Institute of Fluid-Flow Machinery

2015

nr 130

3--29

In course of over half a century the test teams of the Szewalski Institute of Fluid-Flow Machinery (IMP PAN) have conducted numerous performance tests of small hydropower (SHP) installations on various occasions and motivations, including updating or establishing performance characteristics of old machines, acceptance of new units, checking or optimising the cam correlation of new or refurbished double-regulated turbines, checking performance of prototype turbines under field conditions. The discharge measurement techniques have included currentmeter, pressure-time and acoustic methods. Index tests, using the Winter-Kennedy and other differential pressure methods, as well as current-meter and acoustic techniques, have been employed quite frequently to optimise the cam curves of double-regulated machines. In one case a simplified technique based solely on the power/wicket gate opening relationship was checked. This paper discusses some techniques applied when determining the absolute efficiency and optimizing cam correlations by means of absolute and index test methods. Cubic spline formulae as applied to integrate the flow velocity field in a hydrometric section are derived. Results of a discharge measurement by means of the current-meter and pressure-time method are compared as a special case study. Finally, practical recommendations addressed both to the power plant owners and the test team members are formulated.

Modyfikacje procedur obliczeniowych w metodach uderzenia hydraulicznego i młynków hydrometrycznych wykorzystywanych do pomiaru natężenia przepływu w elektrowniach wodnych

Adamkowski A., Krzemianowski Z.

Pomiary Automatyka Kontrola

2014

R. 60, nr 12

1104--1108

Metody uderzenia hydraulicznego i młynków hydrometrycznych są najczęściej używane do pomiaru natężenia przepływu podczas badań energetycznych turbin wodnych. Liczne doświadczenia w stosowaniu ww. metod pomiaru były przesłanką do wprowadzenia nowych elementów, które udoskonalają sposoby całkowania zmierzonych wielkości w procedurach obliczania natężenia przepływu. Modyfikacje te mają na celu poprawę dokładności pomiaru natężenia przepływu rozważanymi metodami.

The hydraulic current meters method and pressure-time method are most commonly used in measuring of the hydraulic turbines. Gained experience in application both mentioned methods in flow rate measurements was basis for the introduction into them new elements that are supposed to improve the accuracy of integration of the measured values. For the pressure-time method, in comparison to the IEC 60041 standard, the calculation procedure has been changed by introducing modifications that concern: (1) the procedure for calculating the hydraulic losses, and (2) determining the upper limit of integration. For current meter method, the calculation procedure has also been changed by introducing modifications that concern: (1) the boundary layer calculated by means of von Karman formula in which some parameters have been introduced instead of the recommended by the ISO 3354 standard, and (2) the way of integrating of the measured velocity field in which NURBS have been applied that allow to avoid some improper shapes of the interpolated profiles. New procedure is compared with other procedures – (1) compatible with ISO 3354, and (2) based on the natural cubic splines. Assessment of the two modified methods was based on the results of the simultaneous flow rate measurement in Polish hydropower plant equipped with Kaplan turbines with penstocks (Fig. 5). The comparison of the results confirmed the validity of new elements introduced to the procedures (Fig. 6).