Investigation on pressure fluctuations of dual - and analogical single-rotor turbine flowmeters

Abstract

As a cutting-edge technology in the field of flow measurement, a dual-rotor turbine flowmeter (DRT-FM) is introduced into the refined measurement in hypersonic flight. In this study, to assess the characteristics of internal pressure fluctuation in the flowmeter, unsteady numerical calculations were performed using rotor motion programs, and the same method was applied to an analogical single-rotor turbine flowmeter. The frequency content, generation reasons, and propagation laws were analysed and compared. The results showed that the pressure fluctuations were primarily from the rotor–stator interaction, and the downstream rotor had a slight influence on the upstream rotor. For the DRT-FM, the characteristic frequency 12.8 f n, composed of blade-passing frequencies of 6 f n and 6.8 f n, was confirmed. Affected by the reverse rotation of the two rotors, 6 f n, 12.8 f n and 6.8 f n developed into the dominant characteristic frequencies between the two rotors, and the amplitude at the downstream rotor inlet was maximal. In addition, compared with the single rotor, although the second rotor increases the pressure fluctuation around it, a more obvious fluctuation attenuation appeared around the downstream transition and support.