242 T.J. Beberniss et al. Fig. 22.7 Experimental set-up for second wind tunnel entry in 2012 [10] PSP (Photron SA5) were triggered simultaneously and images are recorded for approximately 22.5 s at a sampling frequency of 4 kHz for the DIC and 14.5 s at 4 kHz for the PSP images. The PSP sampling was a significant improvement over the previous year of testing. Again, laser vibrometry data and strain gage data are recorded for 60 s sampled at 20 kHz. The tunnel test set-up, with the myriad of cameras, one Litepanel 1 1 Bi-Focus LED lights (305 mm 305 mm, 1152 LED bulbs) for the DIC measurements, and the dual-beam Polytec OFV-552 laser-Doppler vibrometer (LDV), is shown in Fig. 22.7 [10]. In the upcoming series of RC-19 experiments, planned for the winter of 2016, several important changes will be made to this already complex arrangement. Great care will be taken to characterize the flow environment, including a boundary-layer study using a rigid article and moveable rake. The boundary layer height will be measured at two locations along the panel length and at one position near the tunnel wall to quantify edge/corner effects. New high-speed Photron SA-Z DIC cameras with increased memory (from 32 to 64 GB) were purchased that allow for an increase in sampling rate, longer time records, less required lighting, and a 4X reduction in download time. New rigid test articles were also fabricated that will provide discrete, high speed Kulite and PCB pressure transducer measurements, providing a direct comparison with simultaneous PSP measurements. It was noted in a companion, computational study [12], that knowledge of the full-field temperature is necessary, and so temperature sensitive paint (TSP) and PSP will be applied to the flow-side of the test panels. Originally, full-field temperature was to be measured using a forward looking infrared camera (FLIR), but the quartz window above the specimen in Fig. 22.6 significantly filters the IR signature (see Fig. 22.8). Narrower test panels (102 mm versus the original 127 mm wide ones) have also been prepared to allow for greater understanding of the tunnel corner/wall effects on the panel. Specifically, are there appreciable tunnel corner effects, and can the mean pressure loading be assumed uniform (two-dimensional) across the panel surface? This level of loading characterization is important for validation purposes. A fourth camera will be used to record the SBLI and panel interactions via high-speed shadowgraph. Finally, the cavity back pressure will be manipulated to reduce the tunnel/cavity pressure differential, and external heating via halogen lamps will be applied, to create interesting post-buckled and snap-through dynamic conditions. Higher-temperature experiments were conducted during the last series of RC-19 tunnel experiments, and panel buckling was observed. Unfortunately, the heated flow quickly destroyed the PSP and so the dynamic surface pressure was not measured.
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