JPH0328841A - Schlieren device - Google Patents

Abstract

PURPOSE:To accurately observe an impulse wave at low cost even when the size of a body to be tested is large by moving a couple of observation windows over revolution and moving a couple of moving type reflecting mirrors. CONSTITUTION:The transparent observation windows 24a and 25a which have their centers q eccentrically by a specific quantity (a) with the centers of flanges 24 and 25 are fitted in the flanges 24 and 25, and flange rotating devices 26 and 27 are fitted. An observation visual field is set to the front part of the body 23 to be tested, the flanges 24 and 25 are rotated synchronously by the flange rotating devices so that the observation windows 24 a and 25a come to face the part of the body 23 to be tested. Further, when the rear part of the body 23 to be tested is put in the observation visual field, the flanges 24 and 25 are rotated synchronously by 180 deg. to face the rear part of the body 23 to be tested. Then the reflecting mirror 28 and 30 are moved by moving devices 29 and 31 to face the observation windows 24a and 25a. Consequently, the same observation visual field with a couple of large observation windows is obtained with the couple of small observation windows.

Description

[Detailed Description of the Invention] Industrial Application Fields This invention is applicable to wind tunnel experiments on engines, aircraft, etc. Observation of shock wave formation, etc. This invention relates to a Schlieren device used for photographing.

(Conventional technology) First. A conventional schlieren device will be explained with reference to FIG.

Nozzle 1 is installed on the 7111 fuselage 11 that is kept in a vacuum state.
2 and a diff user 13 are provided. [Measurement fuselage] On the sides of 1, there are circular first and second holes, respectively, as shown in Figure 4.
Observation windows 14 and 15 are formed facing each other.

On the first observation window 14 side, as shown in the figure, a first fixed reflecting mirror 16 and a first fixed concave mirror 17 are sequentially arranged.
A tip R18 is arranged opposite to the first fixed concave mirror 17. Similarly, the second observation window 15 includes a second fixed reflecting mirror 19 and a second fixed concave mirror! 20 are arranged one after another, and a light receiver 22 is arranged opposite to the second fixed concave mirror 20 via a knife edge 21 having an aperture mechanism. The above optical system constitutes a Schlieren device.

A test object 23 such as an engine or an airframe is placed in the AIJ L body 11 at a position where it can be seen from the first and second observation windows 14 and 15, and a high-speed airflow flows from the nozzle 12 into the AIJ L body 11.
It is ejected into the fuselage 11. Then, this high-speed airflow is decelerated and exhausted by the diff user 13.

At this time, the light (luminous flux) emitted from the light source 18 is reflected by the first fixed concave mirror 17 and provided to the first fixed reflecting mirror 16 as parallel light. This parallel light is reflected at right angles by the first fixed reflecting mirror 16, and as a result, the parallel light is perpendicularly incident on the first observation window 14. This parallel light passes through the measurement body, is reflected from the second observation window 15 at a right angle by the second fixed reflecting mirror 19, and is reflected at a right angle by the second fixed concave mirror 20.
given to. The parallel light is reflected and focused by the second fixed concave mirror 20 and enters the light receiver 22 via the knife edge 21 as a focused light. Note that the knife edge 21 is placed at the focal point of the focused light, that is, at the focal point of the second fixed concave mirror 20.

Since the focused light incident on the light receiver 22 is partially blocked by the specimen 23, it is possible to observe the shock wave formed around the specimen 22 based on the output from the light receiver 22. In other words, the shock waves are projected onto a cathode ray tube for observation, and video and camera photography are also performed.

Problems to be Solved by the Invention> By the way, when using the above-mentioned Schlieren apparatus to conduct wind tunnel experiments on a test object, such as an aircraft, since the shape of the aircraft is long and narrow, it is difficult to observe the formation of shock waves around the aircraft. for,
The first and second observation windows must be enlarged to fit the aircraft. Furthermore, in order to improve the accuracy of the wind tunnel experiment,
If it is necessary to increase the size of the specimen, the first and second illumination windows must also be increased.

The above-mentioned first and second observation windows need to be created with extremely high precision, and the larger the window diameter, the higher the cost due to the H material and polishing process. For example, the price of an observation window with a diameter of 50c+n is about twice that of a window with a diameter of 40cm. For this reason. Schlieren instruments with large observation windows are necessarily expensive. Furthermore, a circular or rectangular observation window that covers the shape of a long and slender aircraft will be as expensive as a large observation window with the long axis or long side as the aperture.

In addition, l! As the size of the measuring window increases, the reflecting mirror and concave mirror must be made larger, resulting in a higher price for the Schlieren device. For example, the price of the entire device with a diameter of 50 cm is more than twice that of a device with a diameter of 40 cm.

When the size of the specimen is large, shock waves may be observed by setting multiple observation windows on both sides of the measurement body, as shown in Figure 5, by limiting the part of the specimen that is particularly desired for observation. However, in this case, the parts of the specimen located between the observation windows cannot be observed, and moreover, multiple observation windows are provided on one side, making it expensive.

An object of the present invention is to provide a Schlieren apparatus that can accurately observe shock waves at a low cost even when the specimen is large in size, such as long and narrow.

(Means for Solving the Problems) According to the present invention, it is used when conducting a wind tunnel experiment using a measurement body in which a target object is placed, and a circular opening formed on both sides of the measurement body is used. The first rotatably fitted
and a second disc member, and first and second discs formed on the first and second disc members at positions eccentric to the center of the disc member.
a transparent window, a driving means for synchronously rotating the first and second disk members, a light source, and a first concave mirror that converts the light from the light source into parallel light and a first reflecting mirror arranged corresponding to the first disc member and irradiating the parallel light in the direction of the first disc member, and a first reflecting mirror arranged corresponding to the second disc member. a second reflecting mirror that reflects the light from the direction of the second disc member in a predetermined direction as reflected light; a second concave mirror that reflects the reflected light into convergent light; a knife edge section that is disposed at the focal point of the concave mirror and has an aperture mechanism; a light receiver that receives the light that has passed through the knife edge section; and a moving means for moving the light source in a direction along the light source. ! ．． j L, the first and second disc members are rotated and, in synchronization with the rotation, the first and second reflecting mirrors and the first and second transparent windows are respectively opposed to each other; There is obtained a Schlieren device characterized in that the first and second reflecting mirrors are moved in conjunction with each other.

Effect> In the present invention, by rotating the first and second disc members installed in the total 4llj fuselage synchronously by the driving means, the center of the first and second disc members is rotated. The first and second view 7lpt windows (transparent windows) installed at
is moved to an arbitrary observation field of view around the specimen, and the first and second reflecting mirrors are moved relative to the positions of the first and second observation windows, and parallel light is irradiated perpendicularly. 1st and 2nd
The entire large specimen can be observed using the observation window. In other words, a pair of small observation windows can provide the same observation field as a pair of large observation windows.

Example The present invention will be explained below with reference to Examples.

Referring to FIGS. 1 and 2, in this embodiment, the same structural elements as those in the conventional example shown in FIG. 3 are designated by the same numbers, and the explanation thereof will be omitted.

Large-diameter circular openings are formed in the side faces of the total δPJ fuselage 11, facing each other, and circular members (hereinafter referred to as flanges) 24 and 25 are attached to the openings with their outer circumferential surfaces aligned with the inner circumferential surfaces of the openings. are placed closely together.

These flanges 24 and 25 are rotatable relative to the measurement body 11 about the center P thereof.

A circular opening having a center Q is formed in the flange 23 at a position eccentric from the center by a predetermined ma, and a transparent observation window 24a is fitted into this circular opening. Further, a flange rotation device 26 is attached to the outer surface of the measurement body 11, and the flange 23 is connected to the flange rotation device 26. That is, the flange 24 is provided with an observation window 24a whose center is eccentric from the center of the flange 24.

Similarly, the flange 25 also has a predetermined distance from its center.
A circular opening having its center at a position offset by a distance a is formed, and an observation window 25a is fitted into this circular opening. The flange 25 is connected to a flange rotating device 27 attached to the outer surface of the Al1 body 11.

A first movable reflector 28 is arranged on the outside of the measurement body 11 so as to correspond to the flange 24.
- moving reflection t! t28 is connected to the moving device 29.
, whereby the first movable reflector 28 is moved to the measurement body 11.
It is movable along the outer side of the

Similarly, a second movable reflector 30 is arranged on the outside of the measurement body 11 so as to correspond to the flange 25, and this first movable reflector 30 is disposed on the moving device 31. This allows the second movable reflecting mirror 30 to move along the outer side surface of the measurement body 11.

If the front part of the specimen 23 (the left side in Fig. 1) is to be used as the observation field, use a flange rotating device to position the first and second observation windows 24a and 25a in the positions shown in Fig. 2. The flanges 24 and 26 are rotated synchronously (in the direction shown by the solid arrow in FIG. 2) so that the first and second observation windows 24a and 25a correspond to the front part of the specimen 23. Thereafter, the front part of the specimen 23 is observed using the light from the light source 18.

Next, when the rear part of the specimen 23 (the right side in Fig. 1) is to be the observation field, the flanges 24 and 25 are rotated by 180° in the direction shown by the solid line arrow in Fig. 2 using the flange rotation devices 26 and 27, respectively. Rotate synchronously. As a result, the observation windows 24a and 25a are connected to the flange 24, respectively.
and revolves around the center of 25. This corresponds to the rear part of the specimen 23.

In conjunction with the rotation of the flanges 24 and 25, the moving device 29
and 31, the first reflecting mirrors 28 and 30 are moved in the direction shown by the solid arrow in FIG. 1, and the viewing Ap1 windows 24a and 2 are
5a. As a result, the light from the light source 18 (
(parallel light) is irradiated perpendicularly to the observation window 24a.

Note that the observation of shock waves, etc. caused by light irradiation is the same as in the conventional method, and will therefore be omitted.

In this way, the observation window is revolved, and the reflecting mirror that provides parallel light to the observation window is moved in accordance with the revolution of the observation window, so a pair of small observation windows can perform the same observation as a pair of large observation windows. Not only can a field of view be obtained, but also the size of the reflecting mirror and concave mirror can be reduced.

Furthermore, when observing an extremely elongated specimen, by adding an observation window with a large eccentricity from the flange center and a small diameter, it is possible to observe virtually the entire specimen.

Effects of the Invention> As explained above, in the present invention, a pair of observation windows are moved around the orbit and a pair of movable reflectors are moved, so that a wide field of view (radius and eccentricity of the observation windows) M1 can be observed (the field of view obtained by multiplying the square of the addition of π by pi), and only one pair of observation windows is required. We can provide low-cost schlieren equipment.

In other words, since only one pair of low-cost, small-diameter observation windows is used to expand the observation field of view, the observation field of view can be widened and the cost is low. Also. Reducing the size of the observation window means that the size of the reflecting mirror and concave mirror can be reduced, making the Schlieren device itself highly accurate and significantly lower in price.

Even if the size of the specimen becomes larger, this can be handled by increasing the amount of eccentricity mentioned above and increasing the amount of movement of the pair of reflecting mirrors, without completely replacing the general Schlieren apparatus. It also has gender.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the schlieren device according to the present invention, FIG. 2 is a side view of the measuring body shown in FIG. 1, and FIG. 3 is a plan view showing an example of the conventional schlieren device. Figure 4 is a side view of the fuselage shown in Figure 3;
FIG. 5 is a side view showing another example of the scale 1 fuselage used in the conventional Schlieren device. 11...Measurement body, 12...Nozzle, 13...Diff user, 14.15...Transparent observation window, 16.19
... Reflector, 17.20... Concave mirror, 18... Light source, 21... Knife edge, 22... Light receiver.

Claims (1)

[Claims] 1. First and second circles used when conducting a wind tunnel experiment using a measurement body in which a target object is placed, and rotatably fitted into circular openings formed on both sides of the measurement body a plate member; first and second transparent windows formed in the first and second disc members at positions eccentric to the center of the disc member;
a driving means for synchronously rotating the first and second disc members, a light source, a first concave mirror that reflects light from the light source into parallel light, and the first disc a first reflecting mirror arranged corresponding to the member and irradiating the parallel light in the direction of the first disc member; and a first reflecting mirror arranged corresponding to the second disc member and irradiating the parallel light in the direction of the first disc member; a second reflecting mirror that reflects light from the direction of the member in a predetermined direction as reflected light; a second concave mirror that reflects the reflected light into focused light; and a second concave mirror arranged at a focal position of the second concave mirror. , a knife edge portion having an aperture mechanism; a light receiver for receiving light passing through the knife and the edge portion; and a light receiver for moving the first and second reflecting mirrors in a direction along a side surface of the measurement body. has a means of transportation,
When the light source emits light, the first and second disk members are rotated and the first and second reflective mirrors and the first and second transparent windows are rotated periodically with the rotation. A Schlieren device characterized in that the first and second reflecting mirrors are moved in conjunction with each other so as to face each other.