**7.2 A new possible solution for shock wave dispersing through injection of electrons in surrounding airflow through sharp electrodes**

The new possible solution proposed in this paper is based on a massive injection of electrons through very fine and sharp electrodes in the upstream of air stream (in front of aircraft). This solution could be applied in future at the new supersonic jet called Concorde Mark 2 (**Figure 18** [32]).

extremely thin (**Figure 7**, [27]). Inside the shock wave, due to the very small space, the density of electrons and temporary negative molecules is high. As a result, due to electrostatic repelling forces, the shock wave thickness must increase, and its

After passing through the shock wave, the airstream is neutralized by the anodes placed on the aircraft nose and wing, which collect the electrons present in the air

Due to the very high complexity of phenomena, it is risky to make theoretical predictions at this time. The best methodology is to do experiments in a supersonic wind tunnel using various configurations of electrodes connected at high potentials for observing shock wave shape. The shock wave should become weaker similar to the image presented in **Figure 17**. In that case, the significance will be that impact of sonic boom at ground level is mitigated in comparison with the normal case.

If the present system applied at Concorde Mark 2 will be the case, it should be activated in ascending and descending phase when the impact of sonic boom on community is maximum. When the aircraft is flying at very high heights or over the

The new solutions presented in this chapter use dispersion of shock wave through mechanical or electrical means. These solutions are alternatives for

Following the shock wave dispersion, the resulting sonic boom is spread on a much larger area at the ground level, as a consequence, the air in the 'N'shock

A first technological possibility is vibrating a membrane, which is stretched over aircraft nose, wing LE, and horizontal empennage LE. In this case, the membranes are actuated by sonic pulses propagated through a hydraulic liquid. A second solution is vibrating of elastic fairings placed over the aircraft nose,

Injection of electrons in front of aircraft cone/wing/empennage could be a productive technology for reduction of sonic boom impact on community in the

The anode (positive electrode) is composed of multiple copper plates glued

When arriving in the shock wave, these temporary negative molecules and

The cathodes and anodes are electrically insulated by the aircraft frame. The electrons released by the sharp cathodes in the airstream are free or can

be attached by oxygen and nitrogen molecules forming temporary negative

free electrons repel each other dispersing the shock wave. As a result, the

Experiments should be initiated for evaluation of this possible effect. Voltages of many thousands of V should be used because the number of electrons injected in the air stream depends on the value of potential difference

impact of "N" shock wave at ground level will be much reduced.

The cathode (negative electrode) is composed of multiple needles of Wolfram placed on a rod, which is fixed in the tip of aircraft cone or placed

case of supersonic/hypersonic passenger aircraft and business jets.

Low amplitude mechanical vibration of aircraft nose, wing LE, and

impact at ground level will be mitigated.

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

ocean, activation of system is not necessary.

"shaping" solution or using of very thin fuselage.

wave is much smaller than in the normal case.

wing LE, and horizontal empennage LE.

along the leading edges of wing and horizontal tail.

by aircraft nose and wing suction/pressure sides.

between the cathodes and anodes.

horizontal empennage LE leads to shock wave dispersion.

stream.

**8. Conclusions**

molecules.

**127**

The supersonic passenger aircraft Concorde Mark 2 filled in patent [33] by Astrium SAS and European Aeronautic Defense and Space Company would be capable to fly with 4023 km/h (1118 m/s) transporting 20 passengers or 3 tons of cargo on a distance of 8851 km. The duration of travel between London and New York would be of 1 hour.

The cathodes are sharp Wolfram needles placed along a rod, which is fixed in the tip of aircraft nose and along the wing LE (**Figure 18**). The anodes are thin copper sheets, which are fixed by the aircraft nose and pressure/suction sides of wing. Obviously, the anodes and cathodes are electrically insulated by the aircraft frame.

[Note: In **Figure 18**, the dimensions of cathodes are exaggerated for clarity. Actually, they have the dimension of a usual sewing needle].

The system works as follows:

A high potential electrical source (thousands of volts) is connected to the cathodes and anodes by means of an electrically insulated wire network. When the electrical high voltage source is connected to the wire network, a high number of electrons are released through the sharp tips of the cathodes.

[Note: This type of discharge differs by the type of discharge presented in Chapter 6.1 where positive ions are generated through loosing of electrons by atoms due to the primary electrons generated by cathode and accelerated by the potential difference between the cathode and anode].

The released electros are spread in the air stream without generating a significant number of ions because the distance between cathodes and anodes is much larger than in the case of plasma actuators.

The quantity of electrons injected in air stream is very high due to the high number of cathodes and their sharpness and the high potential applied. After detaching the sharp cathodes, the electrons move together with the oxygen and nitrogen molecules to the shock wave, which has the semi-angle β given by Eq. (1) (in the case of oblique shock wave). The injected electrons can be free among the oxygen and nitrogen molecules or can be temporary attached by a part of molecules generating in this way temporary negative molecules.

In this way, the shock wave will be composed of neutral nitrogen and oxygen molecules, free electrons and temporary negative molecules. The shock wave is

#### **Figure 18.**

*New solution proposed for dispersing of shock wave through injection of electrons in surrounding airflow by sharp electrodes [16, 32, 33].*

extremely thin (**Figure 7**, [27]). Inside the shock wave, due to the very small space, the density of electrons and temporary negative molecules is high. As a result, due to electrostatic repelling forces, the shock wave thickness must increase, and its impact at ground level will be mitigated.

After passing through the shock wave, the airstream is neutralized by the anodes placed on the aircraft nose and wing, which collect the electrons present in the air stream.

Due to the very high complexity of phenomena, it is risky to make theoretical predictions at this time. The best methodology is to do experiments in a supersonic wind tunnel using various configurations of electrodes connected at high potentials for observing shock wave shape. The shock wave should become weaker similar to the image presented in **Figure 17**. In that case, the significance will be that impact of sonic boom at ground level is mitigated in comparison with the normal case.

If the present system applied at Concorde Mark 2 will be the case, it should be activated in ascending and descending phase when the impact of sonic boom on community is maximum. When the aircraft is flying at very high heights or over the ocean, activation of system is not necessary.
