**5. Proposed experimental tests for proving of concept**

The effect of shock wave dispersion through mechanical vibrations can be tested in supersonic wind tunnel. At points 4.1 and 4.2, two test equipment are proposed.

The existing methods as schlieren photography are good for observing shock wave dispersion in supersonic wind tunnel.

## **5.1 The test equipment no. 1**

At this equipment, a wedge composed of two elastic lamellae actuated by an electromagnet is used (see **Figure 13**) [26].

**Figure 13.** *The scheme of test equipment no. 1 [26].*

*Sonic Boom Mitigation through Shock Wave Dispersion DOI: http://dx.doi.org/10.5772/intechopen.85088*

The components of experimental equipment no. 1 are:


When electromagnet is powered with an alternative current at the frequency ν equal to the resonance frequency of lamella, the lamellae vibrate at the maximum amplitude. Vibration frequency can be changed if the mass of the two steel pieces is changed. When the weight of steel piece increases, the resonance frequency of lamella decreases and vice-versa. Another role of steel piece is to increase the attraction force of electromagnet on lamella.

Firstly, the shock wave is observed in the window of supersonic aerodynamic tunnel for various speeds when electromagnet is not actuated. The position of shock wave is schlieren photographed for various values of Mach number.

After that, the electromagnet is actuated by the AC having a frequency ν equally to the resonance frequency of lamella, and the shock wave is schlieren photographed for the same Mach number as before (when electromagnet was not actuated).

For every measurement, the shock wave should have variable taper and thickness, depending on vibration frequency and Mach number.

#### **5.2 The test equipment no. 2**

**5. Proposed experimental tests for proving of concept**

*View of a wing with elastic fairings at LE for dispersion of shock wave [30].*

*Environmental Impact of Aviation and Sustainable Solutions*

wave dispersion in supersonic wind tunnel.

electromagnet is used (see **Figure 13**) [26].

**5.1 The test equipment no. 1**

**Figure 12.**

**Figure 13.**

**122**

*The scheme of test equipment no. 1 [26].*

The effect of shock wave dispersion through mechanical vibrations can be tested in supersonic wind tunnel. At points 4.1 and 4.2, two test equipment are proposed. The existing methods as schlieren photography are good for observing shock

At this equipment, a wedge composed of two elastic lamellae actuated by an

The test equipment no. 2 is more complex than test equipment no. 1. It should normally be used as a second step if good measurements are registered during using of equipment no. 1.

This equipment is presented in **Figure 14** [26]. The components of experimental equipment no. 2 are:


**Figure 14.** *Test equipment no. 2 [26].*

A sonic generator sends pressure pulses to the main duct containing hydraulic liquid. The pressure pulses propagate with high speed to the liquid existent between membrane and wedge. As a result, membrane surface is bending and wedge angle increases with Δα.

The experimenting procedure is similar to that presented at point 4.1: Firstly, the shock wave is observed for various speeds when sonic pulses through the main duct with hydraulic liquid are not present. Position of shock wave is schlieren photographed for various values of Mach number.

After that, sonic pulses are sent through the main duct with hydraulic liquid, and the shock wave is schlieren photographed for the same speeds as before.

For every measurement, the shock wave should have a variable taper and thickness depending on frequency and Mach number.

The experiments using the test equipment no. 2 are very useful because they simulate very close the real case on aircraft.
