1. Figure 6. Comparison of theoretical and measured iodine absorption lines relative to the absorption feature at 18789.28 cm-1. from the transmission ratios measured by the wavemeter and cameras. Utilizing the appropriate frequency function (ζ), the frequencies measured as a function of the transmission ratio through the iodine cell (S) are denotedζc1(Sc12), ζc2(Sc34),ζc3(Sc56)andζr(Sr)forthethreePDVcameracomponentsandthewavementer, respectively.
2. In order to make accurate PDV measurements, images are needed to calibrate the camera images spatially. Dot card images were used to provide a spatial reference for each of the six cameras. The physical dot card with equally-spaced circular or rectangle dots was placed at the location of the light sheet so that optical distortions associated with the optical path differences and the oblique viewing angles could be measured. Ideally, the dots should be large enough so that they take up several pixels (8-16) and spaced far enough apart so that the centroids can be determined without interference from neighboring dots (a systematic study of the effect of dot diameter is described by Crafton et al.24). The dot card data could then be used to map the distorted camera images to a Cartesian plane corresponding to the physical dot card location. This process was critical not only to allow velocity measurements fromthe three camera systems to bereferenced to a corresponding physical location,butalso to allow for slight misalignments or magnification differences between the signal and reference images in each camera componenttobe accounted for.
3. IV. Data Processing
4. (model cord)koi(x',y',z') Laser 0.009,1.00,0.021 Component1 -0.802,0.491,0.339 -0.811,0.509,0.318 -0.871,0.509,0.024 Component2 0.775,0.554,0.304 0.766,0.446,0.325 0.832,0.446,0.001 Component3 -0.809,0.48,0.340 -0.817,1.48,0.319 -0.877,1.48,0.026 Table2. Incident,observation, andsystemsensitivity vectors for three component PDVdelta wing measurements in tunnelorientedand modeloriented coordinate systemforpositionsof97.1% and108%rootchord.