A combined system for measurements of high-speed flow by interferometry, schlieren and shadowgraph

Abstract

Details are given of a system for making measurements of a jet flow using interferometry, schlieren or shadowgraph. The system is relatively inexpensive and should be generally applicable for any high-speed flows where density gradients are significant. Particular features of the system are the ease of conversion between modes of operation, the stability of the arrangement and the solution of problems of vibration. A computerised technique for analysis of interferograms is described and the results compare well with independent measurements.

Effect of Airy disk on schlieren diffraction interferometer

“…Because of the complementarity of these methods and the overlap of their ranges of usefulness combination of these methods is particularly valuable for situations involving large range of refractive index gradients generally encountered in gases or plasmas. To get simultaneous information of test object some combined systems have also been reported in the literature [21][22][23] and choice of a particular system depends upon the nature of test field and information required along with other parameters like source of light, space availability, etc.…”

Effects of optical diagnostic techniques on the accuracy of laminar flame speeds measured from Bunsen flames: OH* chemiluminescence, OH-PLIF and acetone/kerosene-PLIF

“…This surface would therefore appear to be unsuitable for directly determining flame speed unless an estimation of the flame thickness (δ) can be determined [8]. The shadow graphic technique measures the derivative of density gradient, which is the result of refraction index variation across the flame front [15]. Past experiments have revealed that the sharp inner shadow graphic edge is dependent on the distance between the flame and the optical detector [16].…”