Author(s)

Junji Nagao, Shigeru Matsuo, Toshiaki Setoguchi, Heuy Dong Kim

Department of Mechanical Engineering, Saga University, Saga, Japan.
Graduate School of Science and Engineering, Saga University, Saga, Japan.
Institute of Ocean Energy, Saga University, Saga, Japan.
School of Mechanical Engineering, Andong National University, Andong, Korea.

A critical nozzle (sonic nozzle) is used to measure the mass flow rate of gas. It is well known that the coefficient of discharge of the flow in the nozzle is a single function of Reynolds number. The purpose of the present study is to investigate the effect of unsteady downstream condition on hydrogen gas flow through a sonic nozzle, numerically. Navier-Stokes equations were solved numerically using 3rd-order MUSCL type TVD finite-difference scheme with a second-order fractional-step for time integration. A standard k-ε model was used as a turbulence model. The computational results showed that the discharge coefficients in case without pressure fluctuations were in good agreement with experimental results. Further, it was found that the pressure fluctuations tended to propagate upstream of nozzle throat with the decrease of Reynolds number and an increase of amplitude of pressure fluctuations.

Compressible Flow; Critical Nozzle; Pressure Fluctuation; Measurement; Supersonic Flow

Nagao, J. , Matsuo, S. , Setoguchi, T. and Kim, H. (2012) Numerical Study on the Effect of Unsteady Downstream Conditions on Hydrogen Gas Flow through a Critical Nozzle. Open Journal of Fluid Dynamics, 2, 137-144. doi: 10.4236/ojfd.2012.24014.