A reflective microwave absorption device for high-speed wind tunnel

Abstract

The present invention discloses a reflective microwave absorption device for a high-speed wind tunnel. The reflective microwave absorption device is installed behind the throat of the high-speed wind tunnel along the incoming flow direction of the high-speed wind tunnel and along the airflow, and includes a front reflective microwave absorption plate array located in front of the front section of the test section and the test model, and a rear reflective microwave absorption plate array located in the rear section of the test section and the test model; both the front and rear reflective microwave absorption plate arrays are flat arrays. The reflective microwave absorption plates are thin flat plates, so that the blockage degree of the front and rear reflective microwave absorption plate arrays in the wind tunnel test section is very low, and does not affect the high-speed wind tunnel flow field; the coordination of the front and rear reflective microwave absorption plate arrays greatly reduces the propagation of reflected microwaves to the upper and downstream, and the array-arranged absorbing angle cones on the surface of the reflective microwave absorption plate further reduce the intensity of the reflected microwaves, ultimately reducing or avoiding the damage of reflected microwaves to wind tunnel equipment and on-site staff, and improving the safety of wind tunnel tests.

Description

Technical Field

[0001] The invention belongs to the technical field of high-speed wind tunnel tests, and in particular relates to a reflective microwave absorbing device for a high-speed wind tunnel. Background Art

[0002] High-power microwave weapons are the nemesis of stealth fighters, which is mainly caused by the design characteristics of stealth fighters themselves. First of all, the stealth absorbing materials commonly used in stealth fighters include special graphite honeycomb materials and resin polymer materials. The working principle of "stealth materials" is to convert radar waves into heat energy and emit them to avoid reflection. At the same time, in order to further enhance the stealth effect, all stealth fighters are sprayed with a fairly thick layer of radar absorbing materials. The working principle of this absorbing material is basically the same as that of "stealth materials". Due to the large-scale use of absorbing materials, the US stealth fighters have good low detectability in front of radar. However, since most military radars currently work in the microwave band, stealth fighters can absorb a large amount of radar waves and microwaves, which creates its own fatal weakness and invites "self-destruction". The fourth-generation aircraft represented by the F22 mainly adopts stealth coating to achieve stealth. Stealth coating has some typical characteristics. First, it has a short life cycle and high maintenance cost. Second, the wave absorption performance drops sharply with the increase of temperature. Third, after local damage, the overall stealth performance of the whole aircraft drops sharply. For example, Andrew Lambert, former director of defense research of the British Royal Air Force, once said: Although Lockheed Martin has improved the stealth coating, a scratch can make the radar signal of the fighter the same as that of the 747. It is precisely because of the second and third characteristics that high-energy microwave weapons have significant advantages in anti-stealth coating. When a stealth fighter is irradiated by high-energy electromagnetic waves, the coating will generate high temperature due to excessive absorption of microwave energy, resulting in a decrease in stealth performance, or further causing cracks in the coating, damage to the appearance, etc., making its stealth capability ineffective.

[0003] With the successful development of solid-state high-power microwave systems, offensive microwave weapons have become possible. The sharp increase in microwave power can become a great threat to future aircraft. When high-power microwaves act on the surface of an aircraft, due to the reflection and diffraction of microwaves, a field enhancement effect is formed in the local area of ​​the aircraft. This effect causes a large amount of energy deposition, which interacts with the absorbing coating on the surface of the aircraft, causing deformation and changing its aerodynamic characteristics. In the process of studying microwave damage effects, many influencing factors are involved, among which the three key parameters are:

[0004] Sensitive frequency: determined by the characteristics of the target itself, and is the frequency point or frequency band to which it is sensitive.

[0005] Power threshold: below a certain power, no destructive effect will occur no matter how large the energy is.

[0006] Energy accumulation: Exceeding the power threshold must still have enough energy to destroy the target.

[0007] In the real flow field, the strong coupling effect between the velocity field and the temperature field will cause the change of the convective heat transfer coefficient in the heat conduction process, which will lead to drastic changes in the power threshold and energy accumulation of the target. Therefore, in order to evaluate the high-energy microwave damage effect of the real aircraft during high-speed flight, it is necessary to carry out microwave damage test research under real flow field conditions. Existing microwave tests are mainly carried out in open environments or microwave darkrooms, without considering the effects of convective heat transfer caused by real airflow.

[0008] At present, there is an urgent need to develop a high-speed wind tunnel microwave damage test device to simulate the influence of real airflow heat conduction on the heat accumulation in the process of microwave damage thermal effect. Because microwaves will be transmitted upstream and downstream in the wind tunnel test section, it is easy to cause damage to wind tunnel equipment and personnel, and must be controlled. Therefore, the reflective microwave absorption device is an important part of the high-speed wind tunnel microwave damage test device, which is used to reduce or avoid the damage of microwave radiation to wind tunnel equipment and personnel. Summary of the invention

[0009] The technical problem to be solved by the present invention is to provide a reflective microwave absorbing device for a high-speed wind tunnel.

[0010] The reflective microwave absorbing device for a high-speed wind tunnel of the present invention is characterized in that the reflective microwave absorbing device is installed behind the throat of the high-speed wind tunnel along the incoming flow direction of the high-speed wind tunnel and along the airflow, and is respectively located at the front section of the test section and in front of the test model, and the rear reflective microwave absorbing plate array is located at the rear section of the test section and behind the test model; the front reflective microwave absorbing plate array and the reflective microwave absorbing plate array are both flat-plate arrays;

[0011] The length of the microwave reflection absorption plate in the airflow direction is L1 = (1 / 6 to 1 / 4) * W, where W is the length of the high-speed wind tunnel test section; the height of the microwave reflection absorption plate is L2 = (1 / 6 to 1 / 4) * H, where H is the height of the cross section of the test section; the thickness of the microwave reflection absorption plate is L3 = 1 mm to 3 mm;

[0012] The front reflective microwave absorption plate array has a1 rows of reflective microwave absorption plates in the height direction of the cross section of the test section, each row of reflective microwave absorption plates includes b1 reflective microwave absorption plates arranged along the airflow with a distance of m, the distance between each row is n, and the height difference between each row is 0 to 0.5L1; a1≥1, b1≥1;

[0013] The rear reflection microwave absorption plate array has a2 rows of reflection microwave absorption plates in the height direction of the cross section of the test section, each row of reflection microwave absorption plates includes b2 reflection microwave absorption plates arranged along the airflow with a distance of m, the distance between each row is n, and the height difference between each row is 0 to 0.5L1; a2≥1, b2≥1.

[0014] The material of the reflective microwave absorption plate is silicon carbide.

[0015] The surface of the reflective microwave absorbing plate has wave absorbing angle pyramids arranged in an array.

[0016] The front edge of the reflective microwave absorbing plate is in a wedge shape.

[0017] The distance A between the rear end of the front reflection microwave absorption plate array and the front edge of the test model is ≥2L, and the distance B between the front end of the rear reflection microwave absorption plate array and the rear edge of the test model is ≥2L, where L is the length of the test model.

[0018] The reflective microwave absorbing plates in the reflective microwave absorbing device for a high-speed wind tunnel of the present invention are thin flat plates, so that the blockage degree of the front reflective microwave absorbing plate array and the rear reflective microwave absorbing plate array in the wind tunnel test section is very low, and the flow field of the high-speed wind tunnel is not affected; at the same time, the reflective microwave absorbing device for a high-speed wind tunnel of the present invention adopts the front reflective microwave absorbing plate array and the rear reflective microwave absorbing plate array to cooperate to greatly reduce the intensity of the reflected microwaves, and the array-arranged absorbing angle cones on the surface of the reflective microwave absorbing plate further reduce the intensity of the reflected microwaves, ultimately avoiding or reducing the damage of the reflected microwaves to the wind tunnel equipment and staff, and improving the safety of the wind tunnel test.

[0019] The reflective microwave absorbing device for a high-speed wind tunnel of the present invention has a simple structure and is easy to install, and can reduce the influence of microwave radiation and improve the safety of wind tunnel tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of installing the reflective microwave absorbing device for a high-speed wind tunnel of the present invention in a high-speed wind tunnel;

[0021] Figure 2 It is a schematic diagram of a reflective microwave absorbing plate in a reflective microwave absorbing device for a high-speed wind tunnel of the present invention;

[0022] Figure 3 It is a schematic diagram of a reflective microwave absorption plate array in a reflective microwave absorption device for a high-speed wind tunnel of the present invention.

[0023] In the figure, 1. test section 2. wind tunnel throat 3. front reflection microwave absorption panel array 4. rear reflection microwave absorption panel array 5. test model. DETAILED DESCRIPTION

[0024] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0025] Example 1

[0026] like Figure 1 As shown, the reflective microwave absorption device for a high-speed wind tunnel of the present invention is installed behind the wind tunnel throat 2 of the high-speed wind tunnel along the incoming flow direction of the high-speed wind tunnel and along the airflow, and is respectively located at the front section of the test section 1 and in front of the test model 5, and the rear reflective microwave absorption plate array 4 is located at the rear section of the test section 1 and behind the test model 5; the front reflective microwave absorption plate array 3 and the reflective microwave absorption plate array 4 are both flat arrays;

[0027] like Figure 2 As shown, the length of the reflective microwave absorption plate in the airflow direction is L1 = (1 / 6 to 1 / 4) * W, where W is the length of the test section 1; the height of the reflective microwave absorption plate is L2 = (1 / 6 to 1 / 4) * H, where H is the height of the cross section of the test section 1; the thickness of the reflective microwave absorption plate is L3 = 1 mm to 3 mm;

[0028] like Figure 3 As shown, the front reflective microwave absorption plate array 3 has a1 rows of reflective microwave absorption plates in the height direction of the cross section of the test section 1, each row of reflective microwave absorption plates includes b1 reflective microwave absorption plates arranged along the airflow with a distance of m, the distance between each row is n, and the height difference between each row is 0 to 0.5L1; a1≥1, b1≥1;

[0029] like Figure 3 As shown, the rear reflection microwave absorption plate array 4 has a2 rows of reflection microwave absorption plates in the height direction of the cross section of the test section 1, each row of reflection microwave absorption plates includes b2 reflection microwave absorption plates arranged along the airflow with a distance of m, the distance between each row is n, and the height difference between each row is 0 to 0.5L1; a2≥1, b2≥1.

[0030] The material of the reflective microwave absorption plate is silicon carbide.

[0031] The surface of the reflective microwave absorbing plate has wave absorbing angle pyramids arranged in an array.

[0032] The leading edges of the reflective microwave absorbing plates in the flat-plate array are all wedge-shaped;

[0033] The distance A between the rear end of the front reflection microwave absorption plate array 3 and the front edge of the test model 5 is ≥2L, and the distance B between the front end of the rear reflection microwave absorption plate array 4 and the rear edge of the test model 5 is ≥2L, where L is the length of the test model 5.

[0034] The present invention is not limited to the above-mentioned specific implementation modes. Various changes made by technicians in the relevant technical field based on the above-mentioned conception without creative work all fall within the protection scope of the present invention.

Claims

1. A reflective microwave absorbing device for a high-speed wind tunnel, characterized in that: The reflected microwave absorbing device is installed behind the throat (2) of the high-speed wind tunnel along the incoming flow direction of the high-speed wind tunnel and along the airflow, and is respectively located at the front section of the test section (1) and in front of the test model (5) and the rear reflection microwave absorbing plate array (4) is located at the rear section of the test section (1) and behind the test model (5); the front reflection microwave absorbing plate array (3) and the rear reflection microwave absorbing plate array (4) are both flat plate arrays composed of reflection microwave absorbing plates; The length of the microwave reflection absorption plate in the airflow direction is L1 = (1 / 6~1 / 4)*W, where W is the length of the test section (1); the height of the microwave reflection absorption plate is L2 = (1 / 6~1 / 4)*H, where H is the height of the cross section of the test section (1); the thickness of the microwave reflection absorption plate is L3 = 1mm~3mm; The front reflective microwave absorption plate array (3) has a1 rows of reflective microwave absorption plates in the height direction of the cross section of the test section (1), each row of reflective microwave absorption plates includes b1 reflective microwave absorption plates arranged along the airflow with a distance m between them, the distance between the rows is n, and the height difference between the rows is 0~0.5L1; a1≥1, b1≥1; The rear reflection microwave absorption plate array (4) has a2 rows of reflection microwave absorption plates in the height direction of the cross section of the test section (1), each row of reflection microwave absorption plates includes b2 reflection microwave absorption plates arranged along the airflow with a distance m between them, the distance between the rows is n, and the height difference between the rows is 0~0.5L1; a2≥1, b2≥1.

2. The reflected microwave absorbing device for a high-speed wind tunnel according to claim 1, characterized in that: The material of the reflective microwave absorption plate is silicon carbide.

3. The reflected microwave absorbing device for a high-speed wind tunnel according to claim 1, characterized in that: The surface of the reflective microwave absorbing plate has wave absorbing angle pyramids arranged in an array.

4. The reflected microwave absorbing device for a high-speed wind tunnel according to claim 1, characterized in that: The front edge of the reflective microwave absorbing plate is in a wedge shape.

5. The reflected microwave absorbing device for a high-speed wind tunnel according to claim 1, characterized in that: The distance A between the rear end of the front reflection microwave absorption plate array (3) and the front edge of the test model (5) is ≥2L, and the distance B between the front end of the rear reflection microwave absorption plate array (4) and the rear edge of the test model (5) is ≥2L, where L is the length of the test model (5).

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