Observing device and method to observe a three-dimensional flow field

An observing device for observing a flow field in a detection space is provided. The observing device includes a light source generating a light beam, a light-deflecting device deflecting the light beam, and a light sheet-generating component receiving the light beam deflected by the light-deflecting device and generating a light sheet in the detection space corresponding to the deflected light beam.

FIELD OF THE INVENTION

The present invention relates to an observing device and method, and more particularly to an observing device and method to observe a three-dimensional flow field.

BACKGROUND OF THE INVENTION

In the field of fluid dynamics, the experiments of the wind tunnel and water tunnel are essential to design, analyze and research in flow machines. Based on such experiments, the variations of a flow around a test object in the flow field can be observed directly. Therefore, in order to visualize the flow field, an appropriate observing method is necessary. The most direct observing method is a visual observing method, i.e. an observing method via images.

Please refer toFIG. 1, which is a diagram showing an observing device and method for observing a flow field according to the prior art. InFIG. 1, the region surrounded by dotted lines indicates a flow field3. Generally, no matter in a wind tunnel or a water tunnel experiment, when one skilled in the art wants to realize the flow dynamics at a specific position, particles will be dropped into the upstream of the specific position in the flow field. For example, for a stable flow field in a wind tunnel, smoke will be released therein, and for a water tunnel, a dye will be suspended therein. Meanwhile, the moving image of the particles are captured and recorded by a camera1. In order to facilitate the observation, a light sheet4generated by a light sheet generator2for traversing the flow field3and thus generating a light sheet section40in the flow field3is provided in the prior art. Since the light axis of the camera1is perpendicular to the plane of the light sheet section40, it is facile for the camera1to focus on each point on the light sheet section40. Furthermore, since what is launch into the flow field3is a light sheet4, the light sheet section40is illuminated particularly. Therefore, the particles (not shown) suspended in the light sheet section40will be illuminated and revealed, which are helpful to take images of the light sheet section40by the camera1.

Please refer toFIG. 2, which is a diagram showing the actual operation of the observing device according toFIG. 1. A test object30configured in the flow field3is in a shape of a wing. When the light sheet crosses the flow field3and a light sheet section40is generated, a wing-shaped section30′ is generated on the test object30. Since the test object30is merely varied in the directions of X-axis and Y-axis of the plane of the wing-shaped section30′ and constant in the direction of Z-axis thereof, only the variations in the directions of X-axis and Y-axis, i.e. the X-Y plane, are needed to be observed instead of in the direction of Z-axis. Accordingly, the light sheet section40crossing the flow field3is in a direction for capturing the image of the X-Y plane, and the flow in the flow field3passes through the test object30along a flowing direction31. Under the condition that the flow field3is stable, pathlines31′ representing the trajectory of particles released into the flow field3and varied by the flow could be observed, and thereby the variations of the flow passing through the test object30are realized.

However, in fact, the test object to be observed in the wind tunnel or the water tunnel usually varies in all the three directions. Supposing the test object30inFIG. 2is varied in Z-direction as well, the flow will have a component in Z-direction when passing through the test object30. However, for the conventional device inFIG. 1, even if the flow field3is maintained in stable, the flow phenomenon in Z-direction still cannot be visualized. Likewise, the respective flow phenomenons in two X-Y planes with different Z-values are hard to be distinguished therebetween by the visualization thereof, and thus an analysis for the two planes is hard to be made.

Accordingly, in order to establish a complete observing result of a three dimensional flow field, a whole new method and apparatus for taking images of the flow field are necessary, and the purpose thereof is to visualize a flow field on different planes nimbly, quickly and almost simultaneously.

Hence, because of the defects in the prior arts, the inventors provide an observing device and method to effectively overcome the demerits existing in the prior arts.

SUMMARY OF THE INVENTION

It is an aspect of the present invention to provide an observing device and method for a three-dimensional flow field having the facility in the visualization and the capability of integrating the analysis data of each point in the three-dimensional flow field to output a complete and reliable analyzed result.

In accordance with an aspect of the present invention, an observing device for scanning a flow in a detection space is provided. The observing device comprises a light source generating a light beam, a light-deflecting device deflecting the light beam, and a light sheet-generating component receiving the light beam deflected by the light-deflecting device and generating a light sheet in the detection space corresponding to the deflected light beam.

Preferably, the observing device further comprises an adjusting lens configured between the light-deflecting device and the light sheet-generating component to collimate the light beam deflected by the light-deflecting device, and an image detector readjusting a focus thereof according to a distance from the image detector to the light sheet for recording an image of the flow.

Preferably, the light sheet traverses an object in the detection space, and the light-deflecting device comprises a reflecting device for deflecting the light beam by moving the reflecting device.

Preferably, the reflecting device comprises a rotator, and a plurality of reflecting mirrors surrounding the rotator for deflecting the light beam by rotating the rotator.

Preferably, the plurality of reflecting mirrors is parallel to tangent lines of a perimeter of the rotator.

Preferably, the light-deflecting device comprises a cam and the light source is configured thereon for deflecting the light beam by revolving the cam.

Preferably, the light-deflecting device comprises a cam and a rocker arm, the cam is contacted with the rocker arm and the light source is configured on the rocker arm so as to deflect the light beam by revolving the cam.

Preferably, the observing device further comprises a rocker arm with the light source configured thereon, a connecting rod, and a drive wheel connected to the rocker arm through the connecting rod for reciprocating the rocker arm by rotating the drive wheel.

In accordance with another aspect of the present invention, an observing device for scanning a flow in a detection space is provided. The observing device comprises a light sheet generator for generating a light sheet in the detection space, and a moving device connected with the light sheet generator for moving the light sheet generator along a direction, thereby the light sheet is produced along the direction.

Preferably, the observing device further comprises an image detector readjusting a focus thereof according to a distance from the image detector to the light sheet for recording an image of the flow.

Preferably, the image detector is positioned for facing the light sheet.

Preferably, the focus of the image detector is synchronously readjusted to comply with a movement of the light sheet generator.

Preferably, the light sheet traverses an object in the detection space, and the moving device comprises a track for moving the light sheet generator.

Preferably, the direction is perpendicular to the light sheet.

Preferably, the direction is perpendicular to a flowing direction of the flow.

In accordance with a further aspect of the present invention, a method for scanning a flow in a detection space is provided. The method comprises steps of generating a light sheet in the detection space, and scanning the detection space by successively producing the light sheet along a direction.

Preferably, the method for scanning a flow in a detection space further comprises steps of providing a light sheet generator, and providing a collimated light beam to the light sheet generator along the direction for successively producing the light sheet, wherein the light sheet traverses an object in the detection space.

Preferably, the method for scanning a flow in a detection space further comprises a step of moving the light sheet generator along the direction parallel to a flowing direction of the flow so as to successively produce the light sheet along the direction.

Preferably, the method for scanning a flow in a detection space further comprises steps of providing an image detector, and recording the scanning of the detection space by using the image detector for obtaining an image of the flow.

Preferably, the method for scanning a flow in a detection space further comprises a step of readjusting a focus of the image detector when the light sheet is successively produced during the scanning period of the detection space.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In order to achieve a better effect on the flow field visualization, a concept of moving a light sheet is proposed in the present invention. The purpose of the present invention is to visualize different planes nimbly, quickly and almost simultaneously by the method of moving a light sheet. As for the flow field on the whole, a three-dimensional flow field is scanned by the present invention. Namely, the present invention is an observing device for observing a three-dimensional flow field.

First Embodiment

Please refer toFIG. 3, which is a diagram showing an observing device for observing a three-dimensional flow field according to a first embodiment of the present invention. The observing device according to the first embodiment of the present invention comprises a moving device21and a light sheet generator2configured thereon, thereby moving the light sheet generator2. Generally, a direct method for moving the light sheet generator2is to configure the light sheet generator2on a track (not shown), like a train on a railroad. Since the convenience of the cyclic operation is taken into account in the first embodiment, a belt mechanism is adopted as the moving device21to carry the light sheet generator2. The belt mechanism comprises a pulley set210and a belt212, wherein the belt212wraps around the pulley set210and the light sheet generator2is configured on the belt212. According to the configuration of the first embodiment, the light sheet generator2can scan a flow field cyclically along one direction, wherein the scan for the opposite direction could be achieved by changing the rotating direction of the pulley set210. The belt212in the first embodiment could be a leather belt, a track or a chain belt.

Please refer toFIG. 3again, wherein five positions401-405of a light sheet4are presented for illustrating the relationships between each component of the observing device of the first embodiment. In general, in order to achieve the optimal visualizing effect, i.e. the lowest compensation for the error, the variation or any required situations, the light axis of the camera1is perpendicular to the plane of the light sheet4at each position401-405. In other words, the light axis of the camera1is parallel to the normal vector of the light sheet4, and thus the front image of the section of the light sheet4at each position401-405could be taken without additional adjustment. If the angle between the light axis of the camera1and the normal vector of the plane of the light sheet4is not zero, an additional compensation for the taken images of the flow field is necessary. Therefore, the angle between the light axis of the camera1and the normal vector of the plane of the light sheet is zero in normal condition unless specific condition or limitation is required. ForFIG. 3, the variations of the flow field on the plane along the direction of the light axis of the camera1are the visualizing emphasis. Accordingly, when the light sheet generator2is successively moved, thereby moving the light sheet4, the direction that the camera is pointing for taking the images is the direction of the light axis and the visualization. Since the light sheet4is moved along a direction of approaching to or leaving from the camera1, the focus of the camera1needs to be readjusted according to a distance from the camera to the light sheet4. In order to readjust the focus immediately in accordance with the movement of the light sheet4, the focusing system (not shown) in the camera1is designed to be synchronous with the moving device21. Based on the foregoing design, the focus of the camera1can be readjusted directly without determining the distance to the light sheet4. Namely, when the light sheet4is at the first position401, the light sheet generator2must be in a specific position at the moment. Since the light sheet generator2is configured on the moving device21and the camera1is synchronous with the moving device21, the camera1is able to focus on the light sheet at the first position41. Likewise, when the moving device21moves the light sheet generator2and thereby moves the light sheet4to the second position402, the third position403, the fourth position404or the fifth position405respectively, the camera1is still able to readjust the focus accurately and quickly. For one moment, there is only one light sheet4; however for a period of time, there is a plurality or even an unlimited plurality of light sheets. Based on the above, the present invention is able to scan a space by the movement of a light sheet.

Second Embodiment

Please refer toFIG. 4, which is a diagram showing an observing device for observing a three-dimensional flow field according to a second embodiment of the present invention. With regard to the first embodiment, there might exist some problems of machine consumption and tremble in the moving device21. Therefore, as shown inFIG. 4, the principle of the light sheet generator5is used in the second embodiment. The principle of the light sheet generator5is to emit a light beam to a light sheet-generating component53, which spreads the light beam into a light sheet. When the light beam is emitted to different positions on the light sheet-generating component53, light sheets4are generated at different positions. Therefore, the scheme of changing the positions where the light sheets4are generated inFIG. 4is achieved by changing the incident positions of the light beam to the light sheet-generating component53, thereby simulating the effect of moving a light sheet and finally achieving the purpose of scanning a flow field in a three-dimensional space.

Please refer toFIG. 4again. A light-deflecting device51is configured in the second embodiment for changing the incident positions on the light sheet-generating component53. In the second embodiment, the light-deflecting device51is a reflecting device51, which is movable for deflecting a light beam. The movement of the reflecting device51is usually performed by a rotation achieved by a revolving shaft51a. When the light beam is emitted from a light source50to the reflecting device51, the reflecting device51will reflect the light beam to the light sheet-generating component53. Since the reflecting device rotates successively, the incident angles of the light beam to the reflecting device51are varied according to the rotation, and thus the reflecting angles thereof are changed. Since the reflecting angles of the light beam are changed, the reflected light beams are emitted to different positions on the light sheet-generating component53for achieving the simulation of moving a light sheet4.

In addition, since the rotation of the reflecting device51is at a fixed point, the incident angles of the reflected light beam to the different positions on the light sheet-generating component53are different. Accordingly, an adjusting lens52is configured between the reflecting device51and the light sheet-generating component53to receive and collimate the reflected light beams. The reflected light beams with different incident angles to the adjusting lens are emitted to the light sheet-generating component53at the same incident angle, and thereby the light sheets4generated at different positions in the flow field are parallel. The adjusting lens52also adjusts the transverse moving speed of light spots, i.e. the adjusted light beams in the light sheet-generating component53move at the same speed. Based on the above, no matter at what incident angles the reflected light beam from the reflecting device is emitted to the adjusting lens52, the light sheets4will move at the same speed.

Please refer toFIG. 4again. In order to achieve the purpose of scanning the flow field (not shown) successively in one direction, besides the revolving shaft51a, the reflecting device51further comprises a plurality of reflecting mirrors51b, which are configured around the revolving shaft51a. The plurality of reflecting mirrors51bmove in accordance with the rotation of the revolving shaft51a, thereby deflecting the light beam emitted from the light source50. In general, the planes of the plurality of reflecting mirrors51bare parallel to tangent lines of the perimeter of the revolving shaft51a. In other words, the normal vectors of the planes of the plurality of reflecting mirrors51bare parallel to the radial directions of the revolving shaft51a. In appearance, the reflecting device51looks like a polygonal reflecting-mirror with a revolving shaft51a, or a polygonal cylinder with a revolving shaft51apassing through the core thereof, wherein the reflecting mirrors are configured on the side faces of the polygonal cylinder or the side faces themselves are reflecting mirrors.

Accordingly, when the reflecting device51rotates, the angles between the light beam and the reflecting mirrors51bare changed continuously. Therefore the incident angles of the light beam to the reflecting device51are varied continuously and thus the reflecting angles thereof are varied as well. In order to simplify the content inFIG. 4, the reflected light beam is presented by a first reflected light beam511, a second reflected light beam512, a third reflected light beam513, a fourth reflected light beam514, and a fifth reflected light beam515, wherein the reflecting angles of the five light beams are different and thus they are reflected to different positions of the adjusting lens52. The five light beams passing through different positions of the adjusting lens52are emitted to the light sheet-generating component53and form light sheets4at different positions in the flow field. Namely, a first light sheet41is generated at a first position, a second light sheet42is generated at a second position, a third light sheet43is generated at a third position, a fourth light sheet44is generated at a fourth position, and a fifth light sheet45is generated at a fifth position. For one moment, there is only one light sheet; however for a period of time, it could be considered as a moving light sheet or a plurality light sheets existing in different time points and at different positions.

Please refer toFIG. 5, which is a diagram showing the operation of the observing device of the second embodiment inFIG. 4. The camera1is configured to look down at the flow field3. Namely, the direction of the light axis of the camera1is parallel to Z-axis, i.e. the “depth” dimension, of the flow field3so as to visualize the variations of the flow field in X-axis and Y-axis. In this embodiment, a test object30A is configured in the flow field3and it is apparent there is an angle, i.e. the angle of attack, between the axis direction of the test object30A and the flowing direction31of the flow in the flow field3. Therefore, the Z-axis value of the test object30A is varied, and the camera1can be used to visualize the variations of the flow in each X-Y plane with respective Z-axis value when the flow is passing by the test object30A. ForFIG. 5, since the reflecting device51rotates in a counter-clockwise direction, the reflected light beams are emitted to the adjusting lens52from bottom up and are transformed to light sheets, such as the first light sheet41, the second light sheet42, the third light sheet43, the fourth light sheet44and the fifth light sheet45, by the light sheet-generating component53. The flow phenomenon in the five X-Y planes with different Z-axis values can be obtained via the five light sheets41-45. Meanwhile, the effect resulting from the test object30A to the flow field3in the five X-Y planes with different Z-axis values also can be known by the existence of the test object30A.

Please refer toFIGS. 4 and 6, whereinFIG. 6is a diagram showing the second embodiment ofFIG. 4with partial modifications. Since the reflecting angles of the reflected light beams, such as the first reflected light beam511, the second reflected light beam512, the third reflected light beam513, the fourth reflected light beam514, and the fifth reflected light beam515, from the reflecting device51are different, an adjusting lens52for collimating the light beams is necessary. However, due to the limitation of the adjusting lens52, there should be a proper distance between the reflecting device51and the adjusting lens52for avoiding that the incident angles of the light beams at two sides, such as the first reflected light beam511and the fifth reflected light beam515, to the adjusting lens52are too large so as to achieve the adjusting effect in expectation. Therefore, a proper distance between the reflecting device51and the adjusting lens52is necessary, which makes the observing device for the three-dimensional flow field occupy a large space. In other words, the design of the second embodiment inFIG. 4needs a larger space, and thus a modified design of the second embodiment is provided inFIG. 6. The modified embodiment inFIG. 6is improved in indirectly using the light sheets41-45emitted from the light sheet-generating component53. The emitting direction of the light sheet-generating component53is inclined for emitting the light sheets41-45to a deflecting-reflecting lens54before entering the flow field3. Based on the above design, the light sheet-generating device5can be configured closely beside the flow field3. Namely, the light sheets41-45from the light sheet-generating device5are generated in a direction along the sideline outside of the flow field3, and then enter the flow field3through the deflecting-reflecting lens54. Therefore, the occupied space of the whole observing device in the modified embodiment inFIG. 6is quite small in comparison with that of the second embodiment inFIG. 4.

Third Embodiment

Please refer toFIG. 7, which is a diagram showing an observing device for observing a three-dimensional flow field according to a third embodiment of the present invention. In this embodiment, the flow field3is scanned in two directions, wherein the first direction, i.e. Y-direction, is under the charge of a first camera1aand the second direction, i.e. Z-direction, is under the charge of a second camera1b. Since the first camera1apoints at the XZ-plane in Y-direction, light sheets in a first group, including a first light sheet41a, a second light sheet42a, a third light sheet43a, a fourth light sheet44aand a fifth light sheet45a, generated by a first light sheet-generating device5aare all perpendicular to Y-axis. Likewise, Since the second camera1bpoints at the XY-plane in Z-direction, light sheets in a second group, including a first light sheet41b, a second light sheet42b, a third light sheet43b, a fourth light sheet44band a fifth light sheet45b, generated by a second light sheet-generating device5bare all perpendicular to Z-axis. In brief, each light sheet generated by the first light sheet-generating device5acan be considered as sub-XZ-planes, and each light sheet generated by the second light sheet-generating device5bcan be considered as sub-XY-planes. In this embodiment, the variations of the flow field3in two directions could be visualized simultaneously by the two observing devices.

If only the XZ-plane is visualized in Y-direction, it assumes that a flow passes through the sub-XZ plane formed by the third light sheet43aof the first group in the moment of visualizing that plane, and then the image of the flow passing through the sub-XZ plane is unable to be taken by the first camera1a. Namely, if the flow field3is visualized in Y-direction, the variations of the flow in Y-direction is hard to be detected. Accordingly, another direction for a complete visualization is necessary, such as Z-direction inFIG. 7. In the third embodiment inFIG. 7, when a flow passes through the sub-XZ planes generated by the first light sheet-generating device5a, the variations of the flow in Z-direction are facile to be detected by the second camera1b.

Fourth Embodiment

Please refer toFIG. 8, which is a diagram showing an observing device for observing a three-dimensional flow field according to a fourth embodiment of the present invention. In this embodiment, the light-deflecting device is a cam device. The cam device comprises a cam512for an eccentric rotation and a follower514contacted with the cam512. The follower514is pushed to the cam512by an elasticity of an elastic element516and is moved via a close contact with the cam. Therefore, due to the contact with the cam512, the follower514is able to reciprocate based on a balance staff514a, and the light beam from the light source50on the follower is able to be emitted to the adjusting lens52. Finally, the light beams collimated by the adjusting lens52are emitted to the light sheet-generating component53in parallel.

Fifth Embodiment

Please refer toFIG. 9, which is a diagram showing an observing device for observing a three-dimensional flow field according to a fifth embodiment of the present invention. In this embodiment, the light-deflecting device is a crank-rocker mechanism. The crank-rocker mechanism comprises a crank513, which drives a rocker517by a connecting rod515and comprises a driving shaft513agenerally connected to a motor (not shown). A first terminal515aof the connecting rod515is connected to an eccentric position (i.e. the position of leaving the driving shaft513a) of the crank513, and a second terminal515bthereof is connected to the rocker517. Therefore, when the crank513is rotated, the rocker517is able to reciprocate based on a balance staff517a, and the light beam from the light source50configured on the rocker517is able to be emitted to the adjusting lens52. Finally, the light beams collimated by the adjusting lens52are emitted to the light sheet-generating component53in parallel. According to the above, a driving wheel can be used to achieve the effects of the crank513by an eccentric connection with the first terminal515aof the connecting rod515.

The various light-deflecting devices mentioned above all can be designed to be synchronous with the focusing systems. When a light beam emitted from the light-deflecting devices, such as the moving device21inFIG. 3, the reflecting device51inFIG. 4, the follower514inFIG. 8and the rocker517inFIG. 9, is emitted to a specific position by an operation of the light-deflecting devices, a light sheet will be generated at a corresponding position in the flow field. Since the operations of the light-deflecting devices and the corresponding positions of the light sheets are anticipated, it is facile for a camera to focus on the light sheets based on the anticipations. It is no more necessary for a camera to detect a distance to a light sheet by a focusing rangefinder thereof, and the focus can be adjusted by moving lenses thereof directly. Based on the above, the focusing speed is improved, and moreover a larger aperture of the camera for absorbing more light by a light-detecting component thereof is allowable, which makes the images taken by the camera sharper.

Sixth Embodiment

Please refer toFIG. 10, which is a diagram showing an observing device for observing a three-dimensional flow field according to a sixth embodiment of the present invention. In this embodiment, a test object30B, which is not parallel to any of X-axis, Y-axis and Z-axis, is put in the flow field3with a flow in a flowing direction31. In order to visualize the flow phenomenon in the axis direction of the test object30B, the light axis of the camera1is adjusted to be parallel to the axis direction of the test object30B. Since the planes of the light sheets4are perpendicular to the light axis of the camera1, they are perpendicular to the axis direction of the test object30B as well. The first light sheet41c, the second light sheet42cand the third light sheet43care respectively perpendicular to the test object30B and thus form a first section30′B1, a second section30′B2and a third section30′B3thereon respectively. Based on the above-mentioned configuration, the flow phenomenon in the axis direction of the test object30B can be visualized by the camera1without being barricaded by the test object30B itself. If the respective visualizing data of X-axis, Y-axis and Z-axis described above are combined, a more complete visualization and phenomenon regarding the flow field3will be obtained.

The concept of the present invention is to scan a three-dimensional flow field by moving a light sheet. TakeFIG. 5for example, the light sheets41-45generated in the flow field3are parallel to the XY plane and are operated to move along Z-axis direction. Theoretically, there is a plurality of light sheets (XY planes) corresponding to each Z-axis value, and each individual light sheet is separately analyzed. Merging the analyzed data of the plurality of light sheets, the phenomenon, which is visualized in Z-direction, of the three-dimensional flow field3is obtained.

Furthermore, takeFIG. 7for example, the phenomenon of the three-dimensional flow field in visualizing directions of Z-axis and Y-axis can be obtained by combining the analyzed data from two cameras1aand1b, which is more precise than that obtained from single visualizing direction.

As to the visualizing direction, firstly, the light axis of the camera is perpendicular to the planes of the generated light sheets for confirming that each point on each light sheet can be focused on the light-detecting component inside the camera. Secondly, the visualizing directions are along the three dimensions of the three-dimensional flow field in principle. However, it is usually necessary to visualize the variations of the flow field with the test object configured therein in various gestures, wherein the test object is facile to become a barrier to visualize the flow field. Accordingly, as shown inFIG. 10, the light axis of the camera1is adjusted to be parallel to the axis direction of the test object30B and thereby the variations of the flow around the test object30B can be visualized almost without any obstruction. If the three dimensions are further taken into account, the analyzed data will be more complete. Based on the foregoing embodiments, it is known that the present invention has a great contribution to the three-dimensional visualization of a flow field.

While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclose embodiments. Therefore, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.