The AF10 is a small-scale wind tunnel with an electric fan and adjustable air flow control. It is the essential base unit for eight different experiment modules that demonstrate key principles and phenomena of air flow.

The unit consists of a sturdy steel framework on which is mounted a fan which supplies air via a flow-control valve to a specially designed plenum chamber and aerodynamically shaped contraction.

Each of the experiment modules fits either to the plenum chamber or to the contraction. The air then exits the experiment module through the bench top and emerges at an exhaust at the rear of the unit. When smoke is used in experiments for visualisation purposes users can fit flexible ducting to the exhaust to direct waste smoke safely away.

Toggle clamps hold the experiment modules, reducing the need for tools. Pressure measurement connections use reliable quick-release couplings. Both of these features make the changeover from one experiment to another simple and quick.

The bench format of the equipment makes it compact, easy to move and store. The unit also has handy shelves and storage space which is ideal to store experiment modules when they are not in use.

The minimum requirement is the AF10 and one of the experiment modules, plus the AF10a manometer as required. Other experiments can be purchased at a later date allowing a complete system to be built up as time and budgets allow.

The model includes a single pressure tapping so, by rotating the model, students can find the pressure distribution around the cylinder. A holder (included with the wind tunnel) supports the model in the tunnel. IMPACT offers several suitable pressure-measuring instruments (available separately).

Using a Pitot tube, students can traverse the model wake to find the downstream pressure distribution and find the drag on the model. They can compare this to direct measurements, obtained using a balance.

IMPACT’s Smoke Generator (AFA11, not included) increases the educational value of the experiments by showing the flow of air around the model.

The Pitot and static tubes fit to the Pitot-static XY traverse to allow pressures to be measured very close to the flat plate’s surface. The traverse allows the boundary layer to be measured at multiple positions.

This is an ancillary for the AF1600 Subsonic Wind Tunnel.

The aerofoil has 20 static pressure tappings along its chord on the upper and lower surfaces. They each connect to tubes that pass through the aerofoil and then out to clear, numbered, flexible tubes. Students can connect the tubes to other optional pressure-measurement instruments. They can then measure the pressure distribution around the aerofoil, from which they can find the lift.

Using a Pitot tube, students can traverse the aerofoil wake to find the downstream pressure distribution and find the drag on the aerofoil.

Students can compare these values of lift and drag with direct measurements found from a balance. They can also compare them with the results from another aerofoil with the same profile, such as the AF1600d. Varying the angle of attack of the aerofoil with respect to the air stream allows students to find the changes to the pressure distribution. It also allows investigations into the critical conditions at stall.

The set includes a plain sphere, hemisphere, dimpled sphere (similar to a golf ball), flat plate and streamlined (teardrop) shape. All mounted on support arms.

This model is good for experiments with lift, drag and pitching moment of fixed wing aircraft. Students can compare results with the high wing aircraft model (AF1600h) which is available to purchase separately.

The wingspan is 266.25 mm and length is 217.5 mm.

SUBSONIC WIND TUNNEL 600MM

A practical open-circuit suction wind tunnel for experiments in aerodynamics. The Subsonic Wind Tunnel is a cost effective option to provide extensive experimental capabilities in aerodynamics.

The wind tunnel gives accurate results and is suitable for undergraduate study and research projects. IMPACT offers a comprehensive range of instrumentation, including a computer-based data acquisition system.

Air passes into the AF1600 through a honeycomb flow straightener and a grille. It then passes into an aerodynamically designed effuser (cone) that accelerates the air in a linear manner before it moves through the working section. Finally it passes through a diffuser, then into the variable speed axial fan. The grille protects the fan from damage by loose objects. The air leaves the fan, passes through a silencer unit and then back out to atmosphere.

The speed of the axial fan (and therefore the air velocity in the working section) is controlled by an electronic drive control in the separate On/Off unit mounted on the tunnel’s associated instrument frame along with other ancillaries.

The working section is of a square section with tapered chamfered corners and an acrylic roof and floor. The sides are full length acrylic panels, one side is hinged at the top and the other is removable. The whole unit is supported in an aluminium framework. Each side panel has a holder to support wind tunnel models. On the top of the working section are two Pitot devices and a wall tapping to measure the static pressure upstream and downstream of the working section.

Two Pitot-static tubes are provided with the wind tunnel. One is fixed near to the inlet of the working section and measures the air-flow rate. The second Pitot-static tube is attached to a two-axis traverse that allows movement horizontally (fore to aft) and vertically, for measurements throughout the working area. The traverse positions are measured using integrated DTI devices. They connect to digital pressure displays so users can observe detailed pressure readings.

A metal frame supports the wind tunnel. The frame includes lockable castors for convenient mobility. Electronic sensors on the included instrumentation can connect to IMPACT’s Versatile Data Acquisition System (VDAS®, included). VDAS® allows accurate real-time data capture, monitoring, display, calculation and charting of all relevant parameters on a suitable computer.

Included with the wind tunnel:

• Three-Component Balance
• Balance Angle Feedback Unit
• Dual Differential Pressure Display Unit
• 32-Way Pressure Display Unit
• Dual Axis Pitot-Static Traverse
• Versatile Data Acquisition System (VDAS-F)

AIRCRAFT MODEL – HIGH WING

It has a wingspan of 266.25 mm, length of 217.5 mm with a NACA2415 wing profile.

FLUTTER WING

Wing flutter is a complex event that arises from a combination of forces. Dynamic, fluid and structural forces all combine to create an unstable reaction. Although not restricted to just wings it is most commonly associated with wings. Due to its highly complex nature it is often misunderstood. It is a type of resonance, when, if the combined forces approach a particular (resonant) frequency, the induced amplitudes grow and can easily cause the wing to break.

The aerofoil suspended on springs within a frame is a NACA 0015 profile. At both ends of the aerofoil are mounting places that allow you to increase the angle of attack. String tethers are in place to limit amplitude during extreme oscillations to protect the aerofoil from damage.