84
3 Subsonic Wind Tunnels
Fig. 3.46 Study of a double deck TGV in the Long Test Section Wind Tunnel (SVL) (© IAT-CNAM)
While the 2.2 m width test section has solid walls, the inclination of the ceiling is
adaptable in order to adjust for the effect of solid blockage over the entire length of
the test section ensuring a zero-pressure gradient. The maximum speed of the rolling
road corresponds to the maximum velocity of the flow in the test section; i.e. 40 m/s.
A boundary layer suction device placed 0.5 m upstream of the moving floor reduces
the thickness of the boundary-layer upstream of the model (17 mm without suction,
9 mm with suction).The tunnel is equipped with conventional steady and unsteady
pressure measurement systems.
3.3.3 Wind Tunnels for Full Scale Automobile
The S4 and S10 wind tunnels of IAT-CNAM were designed to carry out full scale
automobile aerodynamic tests while the S10 wind tunnel allowing also studies on
2/5 scale models. Special arrangements are provided to accommodate many types of
vehicles or models adapted to the characteristics of wind tunnels and to meet the needs
of studies or research in other fields such as aeronautics, railways, civil engineering or
wind power. These closed-circuit wind tunnels have similar characteristics. Their test
sections (5 m wide, 3 m high and 10 m long) have ventilated lateral and upper walls
(see Fig. 3.47). These walls, with longitudinal slots, reduce the blockage created by
3 Subsonic Wind Tunnels
Fig. 3.46 Study of a double deck TGV in the Long Test Section Wind Tunnel (SVL) (© IAT-CNAM)
While the 2.2 m width test section has solid walls, the inclination of the ceiling is
adaptable in order to adjust for the effect of solid blockage over the entire length of
the test section ensuring a zero-pressure gradient. The maximum speed of the rolling
road corresponds to the maximum velocity of the flow in the test section; i.e. 40 m/s.
A boundary layer suction device placed 0.5 m upstream of the moving floor reduces
the thickness of the boundary-layer upstream of the model (17 mm without suction,
9 mm with suction).The tunnel is equipped with conventional steady and unsteady
pressure measurement systems.
3.3.3 Wind Tunnels for Full Scale Automobile
The S4 and S10 wind tunnels of IAT-CNAM were designed to carry out full scale
automobile aerodynamic tests while the S10 wind tunnel allowing also studies on
2/5 scale models. Special arrangements are provided to accommodate many types of
vehicles or models adapted to the characteristics of wind tunnels and to meet the needs
of studies or research in other fields such as aeronautics, railways, civil engineering or
wind power. These closed-circuit wind tunnels have similar characteristics. Their test
sections (5 m wide, 3 m high and 10 m long) have ventilated lateral and upper walls
(see Fig. 3.47). These walls, with longitudinal slots, reduce the blockage created by