© 2016 Your company
Wind Tunnel Type and Layout
Why open blower type?
- Cost and space efficiency: open-circuit tunnels are more economical and require less space than closed-circuit designs.
- Avoidance of recirculation: disturbed air from the working section is not recirculated, improving flow quality for propeller testing.
- Elimination of corners: since corners contribute significantly to pressure losses, their absence in an open-circuit design reduces energy consumption.
- Flexible exit configuration: the exit diffuser can be omitted or adjusted for easier integration into limited spaces.
What are the drawbacks...
1) Blower wake effects: the wake behind the blower must be managed to ensure flow uniformity in the working section.
2) Flow pulsations: blower-driven tunnels may exhibit pulsations, requiring damping measures.
3) Flow separation in wide-angle diffusers: separation is inevitable unless boundary layer control (e.g., screens, curved walls) is applied, albeit at the cost of additional pressure loss.
1) Blower wake effects: the wake behind the blower must be managed to ensure flow uniformity in the working section.
2) Flow pulsations: blower-driven tunnels may exhibit pulsations, requiring damping measures.
3) Flow separation in wide-angle diffusers: separation is inevitable unless boundary layer control (e.g., screens, curved walls) is applied, albeit at the cost of additional pressure loss.
... and mitigation strategies?
1) Area ratio and diffuser angle: higher ratios and steeper angles increase separation risk, necessitating boundary layer control.
2) Screens and flow conditioning: multiple moderate-resistance screens are more effective than a single high-resistance screen [3];
3) Wall Shapes: curved walls (e.g., trumpet-shaped diffusers [4]) reduce separation but are harder to fabricate;
4) Boundary Layer Control Techniques:
a. suction slots (Yang et al. [5]);
b. trapped vortices (Haight & O’Donnell [6]);
c. pyramid gauze diffusers (Gibbings [7]);
d. moving walls (Tennant [8]);
1) Area ratio and diffuser angle: higher ratios and steeper angles increase separation risk, necessitating boundary layer control.
2) Screens and flow conditioning: multiple moderate-resistance screens are more effective than a single high-resistance screen [3];
3) Wall Shapes: curved walls (e.g., trumpet-shaped diffusers [4]) reduce separation but are harder to fabricate;
4) Boundary Layer Control Techniques:
a. suction slots (Yang et al. [5]);
b. trapped vortices (Haight & O’Donnell [6]);
c. pyramid gauze diffusers (Gibbings [7]);
d. moving walls (Tennant [8]);
