Figure 1: NGT2 test setup with laser light sheet in the SWG (up) and mean vorticity magnitude and mean streamline field in the middle of the end car’s length at Re = 4.00E+05 and β = 55° (down).
.
Figure 2: Smoke visualization of the leeward vortical structures of a high-speed train model in the TSG.
Figure 3: Test setup of the NGT2 in the KKK in single end car configuration (up) and with middle car (down).
The certification of high-speed trains requires the adherence to safety rules for cross wind stability. Thus, at DLR Göttingen experimental and computational studies of the flow around trains for various cross wind components are conducted.Two characteristic test facilities for cross wind studies are available. The Side Wind Test Facility Göttingen (SWG), a closed loop wind tunnel with the model fixed on a ground plane, and the Tunnel Simulation Facility Göttingen (TSG) featuring a moving model rig for realistic underfloor aerodynamics.Figure 1 shows the experimental setup and a flow field obtained with Particle Image Velocimetry (PIV) in the SWG at a model of the Next Generation Train (NGT2). In parallel, the aerodynamic loads were measured with a 6-component strain-gauge balance installed inside the end car model.
Figure 2 presents a smoke visualization of the leeward vortical structures of a high-speed train model in the TSG. The model is accelerated by a catapult to a maximum velocity of up to 100m/s. The cross wind flow generated by an additional wind tunnel module of 5m length enables a maximum cross flow of 25m/s.Different scaled models can be used in the TSG (1/20th - 1/100th).
Additional, the Cryogenic Wind Tunnel Cologne (KKK) a closed loop wind tunnel is used to study Reynolds and Mach number effects independently by reducing the gas temperature using liquid nitrogen.
The same test setups are used in the KKK and the SWG with 1/25th scaled models installed on a ground plane. Figure 3 presents the single end car configuration (up) and the configuration with middle car (down) of the NGT2. Both the end car and the middle car model can be equipped with an internal balance.