Abstract: An imaging device can take an image of a flow field including tracer particles includes a compound-eye lens formed from a large number of monocular lenses, which take images of images taken by an imaging lens. Each of the multiple monocular lenses functions as one imaging device. This can enable measurement precision to be enhanced by suppressing the influence of ghost particles, while reducing the equipment cost by minimizing the number of imaging devices. A space for installing the imaging device can easily ensured. If a large number of imaging devices are used, not only do they require time and manpower for setting up, but there is also a possibility that the measurement precision will be degraded due to displacement of an axis of the imaging devices caused by vibration, etc. When the imaging device having the compound-eye lens is used, setup is simplified, and measurement precision can be ensured.

Abstract: A device for measuring a sound source distribution in three-dimensional space is provided in which tracer particles included in a steady flow around an object (12) are irradiated with a two-dimensional laser sheet (Ls) within an x-y plane at two times having a very short time interval, images of the irradiated tracer particles are taken from two intersecting directions in the laser sheet (Ls) by imaging means (32A, 32B), and two in-plane velocity components of the tracer particles in the laser sheet (Ls) and one out-of-plane velocity component perpendicular to the laser sheet (Ls) are measured based on the images taken at the two times. Further, the velocity field of the three velocity components in three-dimensional space is measured by obtaining three velocity components within a plurality of planes spaced apart in a z-axis direction perpendicular to the laser sheet (Ls) and stacking the three velocity components within the plurality of planes in the z-axis direction.

Abstract: Tracer particles together with air are jetted from a nozzle of a seeder into a hood, the air is guided by a collision surface of the hood, deflected to a downstream side in an airflow direction in a wind tunnel, and flows out into the wind tunnel through an opening of the hood. Tracer particles having a large diameter fly straightly without being drifted by the deflected air and collide with the collision surface and are trapped thereon and are prevented from being supplied into the wind tunnel. Tracer particles having a small diameter are drifted by the deflected air, thereby deflected, and supplied into the wind tunnel without collision with and adhesion to the collision surface.

Abstract: A particle image velocimetry system is provided which supplies tracer particles to a flow field around an object (12) from tracer particle supply means, takes an image of reflected light by imaging means (32A, 32B) by irradiating the tracer particles twice with laser light at different times, and determines a velocity vector of the flow field based on the two images obtained of the tracer particles. The two images are each divided into a plurality of test regions, and when first peak value (fp)/second peak value (sp)?1.2 is satisfied by comparison between a first peak value fp and a second peak value sp of a cross-correlation value of a luminance pattern of tracer particles in each test region of the two images, it is determined that the reliability of the velocity vector is high. Thus, it is possible to enhance the precision of measurement of the state of flow by reliably determining erroneous vectors.