Comparison of the Couette flow characteristics in a semicircular channel for air and helium

• Main Authors: Lebiga, V. A., Pak, A. Yu, Zinovyev, V. N., Mironov, D. S.
• Format: Conference Proceeding
• Language: English
• Subjects: Aerodynamics; Composition; Couette flow; Dependence; Flow characteristics; Flow simulation; Flow velocity; Fluid dynamics; Fluid flow; Gas mixtures; Helium; Reynolds number; Self-similarity; Velocity distribution
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0052178

With the help of the created facility for preparation of air-helium mixture of controlled composition experiments were conducted to simulate the flow in a semicircular channel in order to determine the influence of the composition of the gas mixture on the Couette flow characteristics. Data were obtained on the influence of the composition of the air-helium mixture on the dependence of the Nusselt number Nu on the Reynolds number Re for thin wires normally streamlined. It was found that the dependence Nu (Re) for helium is much lower than for air at almost the same Knudsen number. The results obtained supplement the previously determined dependences Nu (Re, Kn) given in [1]. The mean velocity profiles and profiles of the longitudinal component of velocity fluctuation were measured for both air and helium as working gases in a wide range of Reynolds and Taylor numbers. These experiments have demonstrated that the difference in the mean velocity profiles for helium and air with comparable parameters is maximum when approaching the stationary wall of the channel. It was founded that the previously discovered self-similarity of the dependence of the intensity of the flow velocity fluctuations on the Reynolds and Taylor numbers [2], remains within the measurement accuracy when using helium as the working gas. Some results of this work, together with previously published ones, allow to confirm the similarity of the Couette flow in a semicircular channel and in a completely annular channel.