Blow Down Wind Tunnels

Providing an extra degree of testing flexibility


Blow-down wind tunnels are a special type of “Open Circuit” wind tunnel.

For most Open Circuit tunnels, fan assemblies are located downstream of the test section and air is drawn through the wind tunnel with suction. For Blow-down wind tunnels, however, air is blown down into the wind tunnel by a fan (or centrifugal blower) located upstream of the test section, as the name implies.

Compared to standard Open Circuit wind tunnel configuration, AEROLAB blow-down style tunnels provide an extra degree of testing flexibility. Most commonly, these tunnels are used for tests requiring liquid or particulate injection.

Because all AEROLAB tunnels are made to fit the customer’s needs, there is no limitation to the options available. All blow-down style tunnels have custom test sections, and many are requested to include built-in test article mounting arrangements.

Performance Specifications

  • Airspeed Range: customer-defined
  • Turbulence Level: Because the blower is upstream of the test section, flow quality tends to be lower for blow-down tunnels as compared to traditional open circuit or closed circuit tunnels. Still, every effort is made to provide smooth, consistent test section flow.


Blow-down wind tunnels typically employ a centrifugal blower. AEROLAB uses efficient, high-quality, low-maintenance electric motors and state-of-the-art solid-state variable frequency drivers to consistently and accurately set wind tunnel speed.

Wide-angle Diffuser

In order to generate smooth airflow in the test section, the blower-supplied airstream must be slowed and conditioned. The first step in this process occurs in the wide-angle diffuser.

Honeycomb Flow Straightener

To straighten incoming airflow, a “honeycomb” of long narrow tubes is employed. Every AEROLAB wind tunnel is supplied with a high-quality, aluminum, high-aspect-ratio honeycomb flow straightener.

Turbulence-reducing Screens

All AEROLAB tunnels are supplied with two stainless steel turbulence-reducing screens. Also, sufficient space is provided in the wind tunnel framework to fit an additional two screens at a later date should the customer need extremely smooth flow for sensitive experiments.

Specialty Tunnels/Equipment