JPS6218897B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is capable of visualizing fluid flow inside and between blades of rotor blades such as pumps, turbines, blowers, and other high-speed rotating bodies, as well as pressure on the blades from the axial direction. This invention relates to a Schilleren observation device for a high-speed rotating body.

Various experiments have been attempted to visualize the fluid flow inside and between blades of high-speed rotary blades such as turbine blades, but there is no method to observe the blade from the front, especially in modern turbomachinery. As technology advances, visualization methods such as those described above are in demand.

Conventionally, when visualizing the fluid flow inside a high-speed rotary blade or between the blades, a cross-sectional model of the blade is created, placed in a wind tunnel or shock wave tube, etc., and visualized as if the blade were rotating. Fluid is flowed at a given pressure and the flow is observed optically. However, in such an observation method, since the blade is observed from the side, the flow of fluid cannot be observed from the front, and the behavior of the fluid over the entire surface of the blade cannot be observed. Also, the observed model is stationary,
It cannot be said that the flow exactly matches the flow on the actual wing.

The purpose of the present invention is to solve these conventional problems by rotating a high-speed rotating body that can actually be used, or a wing model with an equivalent shape, from the front of the high-speed rotating body. It is an object of the present invention to provide a high-speed rotating body Schlieren observation device that can observe the behavior of fluid inside a body and between blades.

In the present invention, in order to find a place where there is a difference in the refractive index of light (a place where there is a change in gas density), first, the light from the light source is transmitted to the center of the rotation axis of the rotating body by a light shielding member of the reflection/transmission means. The projected light is projected almost perpendicularly to the front of the rotating body along the direction of the rotating body, and the projected light is reflected by a concave mirror provided on the back side of the rotating body. The reflection/transmission means is arranged such that the light shielding member blocks part or all of the reflected light from the concave mirror at the focal position of the concave mirror. The light emitted from the reflection/transmission means is incident on a rotating prism such as a trapezoidal prism whose optical axis coincides with the rotational axis of a rotating body and which rotates at a rotational speed that is synchronized with the rotational speed of the rotating body. Then, the behavior of the rotating body and the fluid inside it or between the blades is observed using the light emitted from the prism.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1A is a front view of a Schilleren observation device for a high-speed rotating body showing an embodiment of the present invention, and FIG. 1B is a plan view thereof. A synchronous motor 1 transmits its rotation to a rotating shaft 3 via a belt 2. A rotating shaft 3 is supported by bearings 4 and 5, and a rotating body 6 to be observed is attached to one end of the rotating shaft 3. In this example, an impeller 6B is attached to a transparent glass plate 6A to form the rotating body 6 to be observed. 7 is a concave mirror provided opposite to the back surface of the glass plate 6A, and 8 is a reflection/transmission means. In this embodiment, prisms 8A and 8B are joined, and a disk serving as a light shielding member is placed approximately in the center of the joining surface. A shaped mirror 9 is provided. The reflection/transmission means 8 is arranged so that the focal point of the concave mirror 7 is located approximately at the center of the mirror 9. Also, the light from the light source 10 is focused on the mirror 9 via the lens 10A. Here, the angle of incidence of the light on the mirror 9 is 45 degrees. The light propagated from the lens 10A is reflected by the mirror 9, projected almost perpendicularly to the rotating body 6 along the rotation axis of the rotating body 6, and further reflected by the concave mirror 7.
reflected. Therefore, if the gas near the rotating body 6 is uniform and the light is not refracted, all reflected light from the concave mirror 7 will be blocked by the mirror 9. 11 is a lens whose optical axis is similarly aligned with the rotational axis of the rotating body 6; 12 is a trapezoidal prism as a rotating prism whose optical axis is similarly aligned with the rotational axis of the rotating body 6; It is rotated by a synchronous motor 14. A synchronous motor 14 is connected to the synchronous motor 1 and synchronized so that the rotation speed of the rotating prism 12 is 1/2 of the rotation speed of the rotating body 6. Reference numeral 15 denotes a photographing device that reproduces a still image of the rotating body 6 using light emitted from the rotating prism 12.

In the Schilleren observation device for a high-speed rotating body configured as described above, light from the light source 10 is passed through the lens 10A and the reflection/transmission means 8 to the rotating body rotating at high speed along the rotation axis of the rotating body 6. Project almost perpendicular to 6. Concave mirror 7 via rotating body 6
The light reflected from the rotating body 6 is transmitted along the axis of rotation through the reflection/transmission means 8 and the lens 11.
The light is made incident on the trapezoidal prism 12 which is rotating at a rotation speed of 2. Entrance surface 12 of prism 12
The light incident on A is reflected by the reflective surface 12B and exits from the exit surface 12C. Photographing device 1 captures the emitted light.
5 to reproduce a still image of the rotating body 6.

The principle by which a still image of the rotating body 6 is observed using such an apparatus will be explained with reference to FIGS. 2A and 2B. In FIG. 2A, the rotating body 6 is schematically indicated by an arrow 20, with one end being 20B and the other end being 20B.
It is assumed to be 0W. The reflected light of the arrow 20 enters the incident surface 12A of the trapezoidal prism 12 via the reflection/transmission means 8 and the lens 11 with the end 20B facing upward. On the reflective surface 12B of the prism 12, the end 20
B is located on the left side in the figure, and the end portion 20W is located on the right side. The reflected light from the reflective surface 12B reaches the exit surface 12C as indicated by the dotted line in the figure, and at the exit surface 12C, the direction of the arrow is reversed, and an image is formed in which the end 20B of the arrow is located downward and the end 20W is located upward. Become.

Rotate the arrow 20 by 180 degrees from the position shown in FIG. 2A to make it appear as shown in FIG. 2B. At this time, the trapezoidal prism 12 is rotated by 90 degrees in the same direction. That is,
In the trapezoidal prism, the incident light is reflected once by the reflective surface 12B at the bottom of the prism and then emitted, so the rotation speed is doubled. Therefore, the rotating body 6
The trapezoidal prism 12 is rotated at half the rotation speed of the arrow 20 as shown in FIG. The image formed on the entrance surface 12A of the prism 12 is in the same direction as the arrow 20, and as shown, the image formed on the exit surface 12C via the reflective surface 12B is also in the same direction as the entrance surface 12A.
The direction is the same as the image above. That is, the end 20
W is located above, and end portion 20B is located below.

In this way, if the trapezoidal prism 12 is rotated in the same direction at half the rotational speed of the rotating body 6 and the emitted light from the exit surface 12C of the trapezoidal prism 12 is observed, a still image can always be obtained.

Even if the trapezoidal prism 12 is a prism of another type, such as a roof-shaped prism, and its rotational speed is synchronized with the rotational object to be observed at an appropriate speed, a still image can be obtained in the same manner as described above.

Thus, in the apparatus shown in FIGS. 1A and B,
When a density gradient occurs in the fluid around the impeller 6B,
A certain part of the reflected light from the concave mirror 7 is blocked by the mirror 9, and a certain part is not blocked by the mirror 9, and the image obtained by the light emitted from the exit surface 12C of the rotating prism 12 includes the fluid Lightness and darkness occur depending on the density gradient. Therefore, it is possible to know the behavior of the fluid around the impeller in a stationary state based on such brightness and darkness.

Note that it is also possible to attach an actual turbine blade or fan to the rotating shaft 3 and observe the behavior of the fluid in the same manner as described above. The shape of the mirror 9 is not a disk shape,
It can also be a polygon.

As explained above, according to the present invention, light is projected from the front of a rotating object to be observed that is rotating at high speed,
The projected light is reflected by a concave mirror provided opposite to the back surface of the rotating body, and part or all of the reflected light from the concave mirror is blocked by a light shielding member at the focal position of the concave mirror. The blocked light enters a rotating prism that is placed with its optical axis aligned with the rotational axis of the rotating body and rotates at a rotational speed synchronized with the rotating body, and the light emitted from the prism forms a static image of the rotating body. Since the behavior of the fluid around the rotating body is observed based on the above, the behavior of the fluid can be observed from the front of the rotating body to be observed while the rotating body is being rotated.

[Brief explanation of the drawing]

FIG. 1A is a front view showing an embodiment of the present invention, FIG. 1B is a plan view thereof, and FIGS. 2A and 2B are diagrams showing the principle by which a still image can be obtained by this embodiment. . DESCRIPTION OF SYMBOLS 1, 14... Motor, 2, 13... Belt, 3... Rotating shaft, 4, 5... Bearing, 6... High speed rotating body, 7... Concave mirror, 8... Reflecting and transmitting means, 8A, 8B... Prism,
9...Mirror, 10...Light source, 10A, 11...Lens, 1
2...Rotating prism, 15...Camera.

Claims (1)

[Scope of Claims] 1. Light from a light source is projected through a rotating body to be observed, and a concave mirror that reflects the projected light; The light shielding member includes a light shielding member that reflects the light toward the concave mirror along the rotation axis and projects the light onto the concave mirror via the observed rotating body, and the reflected light from the concave mirror is incident along the rotation axis. and the light shielding member blocks part or all of the incident light at the focal position of the concave mirror, and the partially blocked incident light is emitted along the rotation axis. a transmitting means, disposed with an optical axis aligned with the rotational axis, into which light emitted from the reflective transmitting means is incident;
It rotates at a speed synchronized with the rotational speed of the rotating body to be observed, emits the incident light along the optical axis, obtains a still image of the high-speed rotating body by the emitted light, and captures the surroundings of the rotating body. 1. A Schilleren observation device for a high-speed rotating body, comprising a rotating prism capable of observing the behavior of a gas. 2. In the device according to claim 1,
A Schilleren observation device for a high-speed rotating body, characterized in that the rotating prism is a trapezoidal prism, and the trapezoidal prism is rotated at half the speed of the rotating body to be observed.