Traceability of ultrasonic transit time based on relative displacement method |
|---|
| Q. Pan, W. D. Lin, Y. Liu, L. Q. Zhang, J. M. Wang, J. Peng |
- Abstract:
- The increasing demand for ultrasonic flow meter (UFM) is due to the absence of moving, protruding parts projecting into the measured flow, transient response, high accuracy and wide range, so that it becomes important in flow measurement. By analyzing the error sources and magnitude of measurements in water, considering the uncertainty caused by sound speed profile and standard length, comprehensively. This research proposes a method to trace the transit time to standard length. Firstly, based on the servo driving and automatic displacement control, a facility which can provide displacement with a minimum displacement step of 10 μm, is designed, and has been precisely calibration by laser interferometer. The error function of water temperature uniformity on transit time measurement is evaluated by theoretical model. A high-precision constant system is developed to control the temperature gradient in water better than 5mK, and the Anton Paar MKT50 platinum wire resistance thermometer is being used as the temperature standard. Assuming that the ultrasonic waveform does not change during propagation in water. The transit time for multiple reflections between fixed stainless steel protective layer and movable reflector is measured. The time difference between two different reflections of same wave can be obtained by high-precision cross-correlation algorithm, and the center frequency of the first five cycles are calculated through Hilbert transform. Through the linear increasing experiments, the effects of reflection times, path length and test temperature to the measurement of transit time are compared.
- Keywords:
- Ultrasonic flow meter; Transit time; Dry calibration; Traceability
- Download:
- IMEKO-TC9-2019-066.pdf
- DOI:
- 10.21014/tc9-2022.066
- Event details
- IMEKO TC:
- TC9
- Event name:
- FLOMEKO 2022
- Title:
19th International Flow Measurement Conference 2022
- Place:
- Chongqing, CHINA
- Time:
- 01 November 2022 - 04 November 2022