Schlieren imaging investigation on azimuthally varying shock net from four-lobed corrugated nozzle

Abstract

Purpose The purpose of this paper is to conduct an experimental investigation on the shock cell structure of jets emanating from a four-lobed corrugated nozzle using Schlieren imaging technique. Design/methodology/approach The Schlieren images were captured for seven different nozzle pressure ratios (NPR = 2, 3, 4, 5, 6, 7 and 8) and compared with the shock cell structure of a round nozzle with an identical exit area. The variation in the length of the shock cell, width of boundary interaction between adjacent shock cells, maximum width of first shock cell, Mach disk position and diameter for different NPR was measured from the Schlieren images and analysed. Findings A three-layer shock net observed in the jet emanating from the four-lobed corrugated nozzle is a novel concept in the field of under-expanded jet flows. A shock net represents interconnected layers of shock cells developed because of the interaction between the core and peripheral shock waves in a jet emanating from a corrugated lobed nozzle. Also, the pattern of shock net is different while taking Schlieren images across the groove and lobe sections. Thus, the shock net emerging from a corrugated lobed nozzle varies azimuthally and primarily depends on the nozzle exit cross section. The length of the shock cell, width of boundary interaction between adjacent shock cells, maximum width of first cell, Mach disk position and diameter were found to exhibit increasing trend with NPR. Originality/value A novel concept of interconnected layers of shock waves defined as “shock net” developed from a single jet emanating from a four-lobed corrugated nozzle was observed.

Geological structure visualization based on UAV and GIS

“…If the resolution level does not change, no operation is required. Otherwise, the next step needs to be judged, and judge whether the edge needs to be simplified or refined based on the error closure value of the current level [5][6]. The resolution of most areas has not changed.…”

“…It is assumed that the UAV model runs at a constant speed and its maximum turning angle is limited by actual conditions. The kinematics equation of UAV based on two-dimensional plane is described in (1).…”

“…The geological body is formed by long-term and complex geological processes. To completely and truly reproduce geological body is a technical problem faced by many scientific fields,the key technology of GS visualization just provides an effective solution [1]. This technology can use computer technology to describe the geological phenomena in the real world as three-dimensional models, intuitively reproduce the characteristics of various underground geological phenomena, imitate the real underground environment, and with strong interaction, so that geological analysts can dynamically, quantitatively and deeply analyze and understand the morphological characteristics, structural changes and spatial distribution of the site strata, so as to obtain detailed Effective geological strata information [2].…”