Planar particle imaging doppler velocimetry: A three-component velocity measurement technique

Digital particle imaging velocimetry (DPIV) is a high-resolution, high-accuracy, planar velocimetry technique, which provides valuable instantaneous velocity information in aeropropulsion test facilities. DPIV is capable of providing three-component flowfield measurements using a two-camera, stereo-viewing configuration. Doppler global velocimetry (DGV) is another planar velocimetry technique, which is also capable of providing three-component flow field measurements, but requires three detector systems that must be located at oblique angles from the measurement plane. The three-dimensional configurations of either technique require multiple (DGV) or at least large (stereo PIV) optical access ports in the facility in which the measurements are being conducted. In some test facilities, limited optical access is available (either a single viewing window or small optical access port), which prohibits the implementation of either technique for three-component flow measurements. A hybrid measurement technique is described, called planar particle image Doppler velocimetry (PPIDV), which combines elements from both the DPIV and DGV techniques into a single detection system capable of measuring all three components of velocity across a planar region of a flowfield through a single optical access port. The PPIDV system utilizes common components between the DPIV and DGV systems to reduce system complexity and costs. Measurements of a rotating wheel are used to verify the integrity of the technique. Then simultaneous measurements of a nozzle flow are obtained using both a stereo-viewing DPIV system and a PPIDV system.