1. Electrical and Mechanical College, Beijing University of Chemical Technology, Beijing 100029, China
2. Division of Thermophysics and Process Meas, National Institute of Metrology, Beijing 100029, China
3. Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
Abstract：The measurement of the thermodynamic temperature with acoustic gas thermometry from 600 K to 1358 K is a promising research direction suggested by the international temperature metrology community. However, traditional acoustic transducers cannot operate at temperatures higher than 400 K, and the solution is to use high temperature alloy acoustic waveguides to transfer the sound from room temperature to high temperature. The design of the acoustic waveguides is key to the signal-to-noise ratio of the acoustic resonances. Acoustic waveguides with larger inner diameter and shorter length are good for the signal transfer, but it will cause larger perturbation to the acoustic resonator. A new kind of acoustic waveguides with variable dimensions to reduce energy loss along the waveguides as well as the perturbation from the ducts was proposed, and a model of the energy loss and the perturbation for the new design was developde, compared the sound attenuation and the perturbation to the acoustic resonance frequencies and half-widths for different dimensions of the waveguides. The optimized design of the acoustic waveguides can reduce the perturbation to the acoustic resonance frequency to below 3×10-5 for the first longitudinal non-degenerate mode of a cylindrical resonator with an inner length of 80 mm. This research contributes to the further study of high-temperature acoustic gas thermometry.
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2019, Vol. 40 
