Purpose
The purpose of this study is to evaluate the effect of tabs having different corner geometries on the flow characteristics of a supersonic convergent–divergent (C-D) nozzle.
Design/methodology/approach
A circular C-D nozzle of Mach 2.0 was used, and the tabs were positioned at the exit of the nozzle in diametrically opposite directions. Three tabs having different corner geometry implemented in the experiments were rectangular tab with triangular top edge, triangular tab with a bell-shaped edge and tapered tab. The pressure profiles across the tabs and the centerline pressure decay along the jets were measured. The shadowgraph technique illustrated the waves present in the center of an oncoming jet. The nozzle pressure ratios (NPR) were varied from 4 to 8, in the steps of one, covering various overexpansion and under expansion levels at the exit of the nozzle.
Findings
The results showed tapered tabs act as a better mixing promoter than the other tabs used in the study. A reduction of 91.25% in core length for NPR 8 was observed for the tapered tabs. Subsequently, core length reductions generated by triangular tabs with a bell-shaped top edge were 87.5%, and those caused by rectangular tabs with a triangular top edge were 7.5%.
Practical implications
The research results could be used for designing combustion chambers and chemical reactors that require jets to enhance mixing levels.
Originality/value
The tabs having three different corners geometries, i.e. sharp or pointed, bell-shaped and straight edge has never been investigated before. The idea of only modifying corners is the innovative step of this research.
In this present work graphite reinforced functionally graded epoxy composites are developed by simple hand lay-up technique. Investigations on wear characteristics of graphite reinforced homogeneous epoxy composites and its functionally graded composite materials developed are presented. The effect of various operational parameters and their interactive influences on specific wear behavior of these composites has been studied systematically. The experimental results indicate that the weight loss increases with increase in load, sliding speed and abrading distance.A plan of experiment based on the technique of central composite design (CCD), was performed to obtain data in controlled way. A standard array, analysis of variance (ANOVA) and response surface methodology were used to investigate the influence of process parameters on the wear of these composites. The results shows that the addition of graphite as a filler material in glass epoxy composite will increases the wear resistance of the composite greatly because the addition of graphite acts as self-lubricating agent during frictional condition & automotive.
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