Quantitative Flow Visualization by Rainbow Schlieren Deflectometry and Pitot Pressure Measurements for Leek Peeler Nozzle Jets

Abstract

To optimize the leek peeling performance, a new nozzle has been developed in which the nozzle has a design Mach number of 1.68, an inner diameter of 2.0 mm at the throat, and an inner diameter of 2.3 mm at the exit. Experiments have been conducted over a range of nozzle pressure ratios from 3.0 to 6.0. Flow field issued from the new nozzle is quantitatively visualized by the rainbow schlieren deflectometry and compared with that from a conventional nozzle. Density fields in the free jets are reconstructed by the Abel inversion method for the schlieren images with the horizontal rainbow filter. The density values at the exit of the conventional nozzle obtained by the rainbow schlieren are compared with the analytical results by the flow model proposed in the past. In addition, Pitot probe surveys along the jet centerline were made to obtain the impact pressure distributions. The Mach number and velocity distributions along the jet centerline are obtained from a combination of the density and Pitot pressure data to clarify the fundamental flow structure of leek peeler nozzle jets.

Application of Rainbow Schlieren Deflectometry for Jets from Round Laval Nozzles Followed by Cylindrical Ducts

“…A comprehensive and thorough review of the rainbow schlieren technique is presented by Agrawal and Wanstall [12], where methods to acquire quantitative density data including mathematical relationship, numerical algorithms, system design criteria, hardware issues, calibrations of rainbow filters, and so on are summarized. Recently, Ezoe et al [13] applied the rainbow schlieren deflectometry for leek peeler nozzle jets to improve the nozzle peeling performance and developed a new nozzle with higher removing potential for peeling leeks in comparison with the conventional nozzle.…”

Multi-Schlieren CT Measurements of Supersonic Microjets from Circular and Square Micro Nozzles

“…However, with a few exceptions (e.g. [22] [23]), most studies used the schlieren technique from a qualitative point of view and not for quantitative measurements. In most studies, quantitative measurements of the jets spreading as well as shock-cell spacing were obtained using micro-pitot probe surveys.…”