INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 3, ISSUE 3, MARCH 2014 ISSN 2277-8616 55 IJSTR©2014 www.ijstr.org Source Equation Analysis Of Cavitation In Fluid Flow Over A Surface Madan M. Jagtap, Dr.Bipin B. Shrivastava ABSTRACT: The main objective of this paper is to form source equation for cavitation.Mathematical analysis of physical phenomenon gives an ease for the study of parameters. Cavitation phenomenon critically affects several applications of hydronautics and hydrodynamics. cavitation shows losses in several turbines as well as pumps. Inception of cavitation over a surface caused due to fall in pressure below atmospheric. Pressure difference in flow gives rise to spherical bubbles. For physical interpretation one can think for coefficient of pressure as threshold value for inception of cavitation. Deciding parameters for range of operation of rotodynamic machines and performance of same can be decided with mathematical equation. Simulation of Mathematical equation on computer will give cost efficient experimental base for designing machines Keywords: Cavitation, Coefficient of pressure, Separated flow, Unseparated flow ———————————————————— I. INTRODUCTION Cavitation is phenomenon which can be understood for detailed flow. It helps to analyze parameters in flow losses over surface. Cavitation for unseparated flow as well as separated flow have different physical reasons. There are Microscopic and macroscopic approach of cavitation. II. EQUATIONS AND ANALYSIS III Inception of Cavitation (macroscopic approach): III.1 Unseparated Flow: Surfaces experience continuous flow. Difference in pressure over surface results in inception of cavitation. One can clearly define origin of cavitation as ratio of difference in pressure to total dynamic pressure. Flow without separation has certain assumptions, given equation for minimum coefficient pressure varies accordingly, in fluid flow particular size of nucleus has minimum pressure that is responsible for instability of that nucleus. Let us consider minimum pressure as critical pressure (p*) for size of nucleus, it may be less than vapor pressure. Based on this commencement of cavitation can be Seems to be modified form of Above equation explains relationship between vapour pressure (p v ) and cavitation inception, It makes a threshold for cavitation in unseparated flow. Density (ρ) and free stream velocity (v) of flowing fluid makes Cavitation inception independent for particular fluid. Free stream pressure makes a difference for cavitation as its value increses inception will increase. C pmin varies according to different flow conditions, It’s value over surface is not desirable to avoid it Figure.1 Above figure shows cavitation inception corresponding to C pmin over surface. III.2 Separated Flow Deceleration of flow over surface indicates boundary layer separation and makes it difficult to observe minimum pressure, as a result minimum pressure coefficient is merely indication of cavitation inception. Therefore it is essential to define different coefficient of pressure based on minimum pressure coefficient which will consider stream velocity for cavitation inception. For Separated boundary layer, velocity of flow will be given by the following equation ,min 2 1 2 o p p p c v ρ ∗ − = ,min 2 2 2 1 1 1 2 2 2 v v o v v o p p p p p p p p p c v v v ρ ρ ρ ∗ ∗ − + − − − = + = ,min (1 ) s p u v c = − _________________________________ • Mr. Madan M. Jagtap, Department of Mechanical Engineering, Saraswati College of Engineering, Kharghar, Navi Mumbai, E-mail: jagtap.aero@gmail.com • Dr.Bipin B. Shrivastava, Ex-Principal, Saraswati College of Engineering. Kharghar, Navi Mumbai, E-mail: drbbshrivastava@gmail.com