・About DWT/MSBS Group
The DWT/MSBS group is developing and improving a magnetic suspension and balance system (MSBS) and conducting wind tunnel tests using it. In a typical wind tunnel test, the model is supported in the wind tunnel by mechanical devices such as stings, struts, or wires. The MSBS can perform wind tunnel tests in an ideal environment without supportive interference, which is difficult to reproduce in conventional wind tunnel experiments. Since it is also possible to not only static support but also dynamic support, we also perform dynamic wind tunnel tests.

・About MSBS
MSBS is a system to levitate and support a wind tunnel model using the magnetic force generated by electromagnets placed around the flow channel. It can be used to solve the support interference problem that cannot be avoided in normal wind tunnel tests. This device can control the posture of the model with multiple degrees of freedom by changing the coil current in dynamic. In addition, the air force acting on the model can be estimated from the coil current value. In addition to static support, it is also possible to move the model as shown in the movie below. We are using two MSBS with different sizes, one of which is 0.3-m MSBS, which can be attached to the Tohoku-University basic aerodynamic research wind tunnel (T-BART). The other one is 1.0-m MSBS, which is owned by the Institute of Fluid Science, Tohoku University. This is the world's largest MSBS and can be installed in a low-turbulence heat transfer wind tunnel.

1. Study on flow around a freestream-aligned circular cylinder (0.3-m MSBS)
 The figure below shows a PIV measurement of a statically supported cylinder using 0.3-m MSBS, which enables us to measure the flow field without support interference and enables us to acquire highly accurate data even in problem settings that are easily affected by mechanical support devices. By measuring the velocity field in synchronization with the aerodynamic force, the relationship between the wake and the aerodynamics can be discussed. In addition, we have developed a wireless pressure measurement device that can be built into the model, which enables us to measure the pressure on the surface of the model synchronously.

Statically supported cylinder using 0.3-m MSBS


2. Study on dynamic wind tunnel testing of flow around a freestream-alined circular cylinder (1.0-m MSBS)
 MSBS can be used for dynamic support as well as static support. The figure below shows the visualization of the wake in static (left side) and dynamic (right side) wind tunnel tests of a cylinder using 1.0-m MSBS. It is shown that the wake width increases when the excitation is matched to the fluctuating frequency of the wake, and it is clarified that the aerodynamic force acting on the cylinder is amplified. We can see that there is a difference in the vortex structure in the wake.


3. Improvement of model position detection method toward wind tunnel testing of a non-axisymmetric model using MSBS (1.0-m MSBS)

The MSBS operated at Tohoku University has been basically applied only to axisymmetric objects due to the characteristics of the model position detection method. However, for practical applications, such as aircraft models, it is necessary to support non-axisymmetric models. The figure below shows a mock-up of a spaceplane supported by 1.0-m MSBS. The model position detection method has been improved for wind tunnel testing of non-axisymmetrical objects and has been applied to tunnel testing of several kinds of model geometries.

Spaceplane model levitated by 1-m MSBS


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