Experimental Analysis of Influencing Factors on Flow Stability of Water Flow Facilities |
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| T. Meng, C. Xing, B. Wu, C. Wang, H. C. Shi, X. P. Li |
- Abstract:
- Because the flow fluctuation can cause the deviation of flow measurement, flow stabilizing methods are used, in the most of the flow metering facilities. Two common flow stabilizing methods of water flow facilities are tested by a new flow stability measurement system which is consisted by a flowmeter and a pressure sensor.
The amplitude of fluctuation can be measured by flowmeter, and the frequency of fluctuation can be obtained by FFT (Fast Fourier Transform) analysis of the pressure signal. The direction of fluctuation source can be distinguished by correlation analysis of pressure and flow signals. Based on this method, the characteristics of the fluctuation source can be obtained by experiments under different flow rate and pipe pressure. An obvious fluctuation signal with a frequency of about 1.5Hz had been found in a test for a flow facility with a buffer tank. The amplitude of fluctuation increases with the decrease of flow rate. When the flow rate is less than 1/10 of the rated flow rate of the pump, the amplitude of fluctuation is about 1%. It is shown that the high frequency fluctuation produced by the pump can be effectively isolated by the buffer tank, but the low frequency fluctuation can be caused by the pump when it worked in a low efficiency range.
In another set of experiments, a flow facility with a constant head water tank and a buffer tank was tested, and two flow stabilizing methods were directly compared and analysed. The test results of the two methods are close under the similar working flow rate and pressure. And if it is under different operating conditions, the amplitude of fluctuation is closely related to the opening of the regulating valve which is installed downstream of the test bench. The fluctuation amplitude increases with the decrease of the valve opening. When the valve opening is less than 30%, the fluctuation amplitude is about 0.5%. Further, it is obtained that the cavitation is caused by the excessive local pressure loss of the regulating valve is the main reason of the facility with constant head water tank.
In summary, the buffer tank and the constant head water tank are both effective methods for stabilizing flow, and the optimal stabilization effect can be obtained by setting a reasonable range of operation for the pump and the regulating valve. - Keywords:
- flow stability, water flow facility, buffer tank, FFT, correlation analysis
- Download:
- IMEKO-TC9-2019-048.pdf
- DOI:
- -
- Event details
- IMEKO TC:
- TC9
- Event name:
- FLOMEKO 2019
- Title:
18th International Flow Measurement Conference 2019
- Place:
- Lisbon, PORTUGAL
- Time:
- 26 June 2019 - 28 June 2019