Compact open circuit wind tunnels
Blower type wide-angle open circuit wind tunnel for propellers
We started this project because we needed an accessible facility to run dynamic tests on propellers.
When we kicked off the design in April 2025, our starting point was:
1) An existing blower-type fan with fixed performance and size.
2) Some available space in the underground floor.
That was it. With these two constraints, the requirement was to build a wind tunnel
capable of testing the largest possible propeller diameters at the highest possible speeds!
The fan design forced us to place it at the tunnel’s inlet, while the room layout dictated an open-circuit configuration.
To achieve the best possible flow quality in the working section—meaning minimal turbulence and angularity—we needed a contraction section with the highest feasible area ratio. That, in turn, required a wide-angle diffuser to make the contraction fit within our limited space.
Step by step, the tunnel’s shape and size naturally emerged from these constraints.
What’s ready now:
- Overall design and structural plans
- CFD analysis of the tunnel and honeycomb
Next steps:
1) CFD analysis of the tunnel inside the room,
2) Purchase of pressure and velocity sensors,
3) Explore, improve, and manage the flow quality in the working section, and eventually
Test real propellers and enjoy the expansion of our design capabilities!
We started this project because we needed an accessible facility to run dynamic tests on propellers.
When we kicked off the design in April 2025, our starting point was:
1) An existing blower-type fan with fixed performance and size.
2) Some available space in the underground floor.
That was it. With these two constraints, the requirement was to build a wind tunnel
capable of testing the largest possible propeller diameters at the highest possible speeds!
The fan design forced us to place it at the tunnel’s inlet, while the room layout dictated an open-circuit configuration.
To achieve the best possible flow quality in the working section—meaning minimal turbulence and angularity—we needed a contraction section with the highest feasible area ratio. That, in turn, required a wide-angle diffuser to make the contraction fit within our limited space.
Step by step, the tunnel’s shape and size naturally emerged from these constraints.
What’s ready now:
- Overall design and structural plans
- CFD analysis of the tunnel and honeycomb
Next steps:
1) CFD analysis of the tunnel inside the room,
2) Purchase of pressure and velocity sensors,
3) Explore, improve, and manage the flow quality in the working section, and eventually
Test real propellers and enjoy the expansion of our design capabilities!
Here are some of the preliminary results, showing the tunnel's geometry and performance, as well as insightful trends.
Flow straightening and turbulence management
To ensure uniform flow in the working section, the tunnel is equipped with
four stainless steel screens and a honeycomb section.
- Screens (4 pcs): 1×1 mm mesh, 0.24 mm wire thickness — porosity 0.61
- Honeycomb: 19×19×150 mm cells, 0.45 mm strip thickness — porosity 0.93
This combination effectively reduces flow angularity and large-scale
turbulence before the contraction.
To ensure uniform flow in the working section, the tunnel is equipped with
four stainless steel screens and a honeycomb section.
- Screens (4 pcs): 1×1 mm mesh, 0.24 mm wire thickness — porosity 0.61
- Honeycomb: 19×19×150 mm cells, 0.45 mm strip thickness — porosity 0.93
This combination effectively reduces flow angularity and large-scale
turbulence before the contraction.
Flow straightening and turbulence
management
To ensure uniform flow in the working
section, the tunnel is equipped with four
stainless steel screens and a honeycomb
section.
- Screens (4 pcs): 1×1 mm mesh, 0.24 mm
wire thickness — porosity 0.61
- Honeycomb: 19×19×150 mm cells, 0.45 mm
strip thickness — porosity 0.93
This combination effectively reduces flow
angularity and large-scale
turbulence before the contraction.
management
To ensure uniform flow in the working
section, the tunnel is equipped with four
stainless steel screens and a honeycomb
section.
- Screens (4 pcs): 1×1 mm mesh, 0.24 mm
wire thickness — porosity 0.61
- Honeycomb: 19×19×150 mm cells, 0.45 mm
strip thickness — porosity 0.93
This combination effectively reduces flow
angularity and large-scale
turbulence before the contraction.
