Loading...
Search for:
cavitation-inception
0.009 seconds
Measurement and Numerical Analysis of Submerged Propellers Noise in Far Field
, Ph.D. Dissertation Sharif University of Technology ; Seif, Mohammad Saeed (Supervisor) ; Mehdigholi, Hamid (Supervisor)
Abstract
This thesis is concerned with measurement and analysis of noise for an underwater propeller by means of numerical and experimental methods. A major cause of noise in buoyant bodies is the propeller. Detection and measurement of such noise is a part of various engineering and maritime applications. Thus detecting the sources of sound and ways of its propagation under water is the first step in many engineering and maritime applications of underwater acoustics which leads to noise reduction and control. Due to its wide subject, this thesis presents a phenomenology of propeller noise and discusses numerical and experimental methods. In the section that deals with numerical methods, the...
Influence of afterbody and boundary layer on cavitating flow
, Article International Journal of Engineering, Transactions B: Applications ; Volume 22, Issue 2 , August , 2009 , Pages 185-196 ; 1728-144X (ISSN) ; Rad, M ; Sharif University of Technology
Materials and Energy Research Center
2009
Abstract
The characteristics of a cavitation water tunnel test setup and the experiments of cavitation around different models are given in this paper. Models of test are formed from combination of head and variable length afterbody. The experiments are performed initially with the smooth head and then with the roughened head. Cavitation initiates both in the wake and after the head. If the nose of models is roughened then cavitation initiates at the lower cavitation numbers. The cavitation inception is a function of the model geometry, nose condition and upstream flow characteristics. During the measuring process of drag force from non-cavitating flow regions to supercavitation case, only the tunnel...
An experimental investigation of hydrodynamic performance, cavitation, and noise of a normal skew B-series marine propeller in the cavitation tunnel
, Article Ocean Engineering ; Volume 238 , 2021 ; 00298018 (ISSN) ; Razaghian, A. H ; Tootian, A ; Seif, M. S ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In this paper, the hydrodynamic performance, cavitation inception, and acoustic performance of a 5-bladed B-series propeller are experimentally investigated in the Sharif University of Technology cavitation tunnel. For hydrodynamic performance, thrust, torque, and efficiency of the propeller model were measured in open water tests. In the cavitation study, in addition to blade cavitation, tip vortex cavitation was also observed, and the cavitation bucket diagram was extracted in different advance coefficients. Finally, for the acoustic analysis of the propeller, the emitted noise in the cavitation tunnel was recorded using two hydrophones according to the recommended procedures of the...
Experimental analysis of cavitaion effects on drag force and back pressure of circular cylinder with free turbulence
, Article Scientia Iranica ; Volume 16, Issue 4 B , 2009 , Pages 344-353 ; 10263098 (ISSN) ; Rad, M ; Sharif University of Technology
2009
Abstract
The characteristics of a cavitation water tunnel test setup and the experiments of cavitation around a circular cylinder with free stream turbulence are presented in this paper. The Reynolds number of flow is limited in the range of 1.26 × 105 to 3 × 105 and the far upstream flow has free turbulence. Drag force, back pressure, location of cavitation inception, length of cavity and appearance of cavitation are measured or observed and their results are presented here. It was found that the cavitation effects on the boundary layer and separation of flow over the cylinder and drag force become minimum at the cavitation number of 1.94. The cavitation inception occurs in the sub-layer and at an...