Subsonic and transonic wind tunnel

<h2 id="closed-wind-tunnel">Closed wind tunnel</h2>

<p>In a return-flow wind tunnel, the return duct must be properly designed to reduce the pressure losses and to ensure smooth flow in the test section.
</p>
<h2 id="transonic-tunnel">Transonic tunnel</h2>
<p>High subsonic wind tunnels, between Mach 0.4 and 0.75, and transonic wind tunnels, between Mach 0.75 and 1.2, are designed on the same principles as the subsonic wind tunnels. Testing at transonic speeds presents additional problems, mainly due to the reflection of the shock waves from the walls of the test section. Therefore, perforated or slotted walls are required to reduce shock reflection from the walls. Since important viscous or inviscid interactions occur (such as shock waves or boundary layer interaction) both Mach and Reynolds number are important and must be properly simulated.
Large-scale facilities and pressurized or cryogenic wind tunnels are used.
</p>

<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Wind_tunnel/yNFbccXQ">Wind tunnel</a></li>
<li><a href="/facts/Supersonic_wind_tunnel/ktKdvaQY">Supersonic wind tunnel</a></li>
<li><a href="/facts/Hypersonic_wind_tunnel/q2MkWYmn">Hypersonic wind tunnel</a></li>
<li><a href="/facts/Gustave_Eiffel/6lo8SFob">Gustave Eiffel</a></li>
<li><a href="/facts/Royal_Netherlands_Aerospace_Centre/QPTuc9vh">National Aerospace Laboratory</a>, Netherlands</li>
<li><a href="/facts/Calspan/fsAVXaPA">Calspan</a></li></ul>

Subsonic and transonic wind tunnel open-in-new

Subsonic and transonic wind tunnel