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Planar particle imaging Doppler velocimetry: a hybrid PIV/DGV technique for three-component velocity measurements

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 flow field 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 (3D) 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, only 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. The resulting system is capable of measuring all three components of velocity across a planar region of a flow field through a single optical access port. An error analysis is performed which reveals an optimal configuration for the DGV portion of the measurement system. 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 the PPIDV system.