Analysis of Hydrogen Leakage and Diffusion in Vehicle Wind Tunnel Based on CFD

Abstract:

With the rapid development of hydrogen fuel cell vehicles （HFCVs）， it is possible for hydrogen fuel cell vehicles to be tested in wind tunnels. In this paper， the flow diffusion law and distribution of hydrogen in wind tunnel under the condition of HFCV leak were studied by numerical simulation. When the wind tunnel simulates the driving condition of the HFCV at 80 km/h， the leaking hydrogen moves against the surface of the car and into the wake area. The hydrogen concentration decreases with increasing distance from the car. The hydrogen entering the flow channel from the collecting port is concentrated in the middle and bottom， with an obvious concentration gradient， and becomes uniform after passing through the fan section. After 10s， the hydrogen leaking from the bottom of the car returned to the test section and merged with the hydrogen leaking from the car， resulting in a continuous increase in the concentration of hydrogen in the entire area. The concentration of hydrogen inboard path increases faster than outboard path due to the deflectors at the corner of the channel. When the wind tunnel simulates the idling condition， the leaking hydrogen mostly diffuses in the test section and almost no hydrogen is detected in the flow channel. Affected by airflow disturbance in the test section， the hydrogen on two sides of the vehicle presents an unsymmetrical distribution， the hydrogen at the top is concentrated on the left side of the HFCV.Finally， according to the numerical simulation results， the installation position of the hydrogen sensors is suggested.

Key words:wind tunnel;hydrogen fuel cell vehicles (HFCVs);hydrogen leakage;numerical simulation