Experimental and numerical study of cavitating flow around a surface mounted semi-circular cylinder
Artikel i vetenskaplig tidskrift, 2020

In this paper, the cavitating flow around a bluff body is studied both experimentally and numerically. The bluff body has a finite length with semi-circular cross section and is mounted on a surface in the throat of a converging-diverging channel. This set-up creates various 3D flow structures around the body, from cavitation inception to super cavities, at high Reynolds numbers (Re = 5.6*10^4 - 2.2*10^5) and low cavitation numbers (sigma = 0.56 - 1.69). Earlier studies have shown this flow to be erosive and the erosion pattern varies by changing the flow rate and w/o the cylinder; hence, this study is an attempt to understand different features of the cavitating flow due to the cylinder effect. In the experiments, high-speed imaging is used. Two of the test cases are investigated in more detail through numerical simulations using a homogeneous mixture model. Non-cavitating simulations have also been performed to study the effect of cavitation on the flow field. Based on the observed results, vortex shedding can have different patterns in cavitating flows. While at higher cavitation numbers the vortices are shed in a cyclic pattern, at very low cavitation numbers large fixed cavities are formed in the wake area. For mid-range cavitation numbers a transitional regime is seen in the shedding process. In addition, the vapour structures have a small effect on the flow behaviour for high cavitation numbers, while at lower cavitation numbers they have significant influence on the exerted forces on the bluff body as well as vortical structures and shedding mechanisms. Besides, at very low cavitation numbers, a reverse flow is observed that moves upstream and causes the detachment of the whole cavity from the cylinder. Such a disturbance is not seen in non-cavitating flows.

Bluff body

Multiphase flow

High speed imaging

Cavitation

Författare

Ebrahim Ghahramani

Chalmers, Mekanik och maritima vetenskaper, Marin teknik

Saad Jahangir

TU Delft

Magdalena Neuhauser

Andritz Hydro

Sébastien Bourgeois

Andritz Hydro

Christian Poelma

TU Delft

Rickard Bensow

Chalmers, Mekanik och maritima vetenskaper, Marin teknik

International Journal of Multiphase Flow

0301-9322 (ISSN)

Vol. 124

CaFE

Europeiska kommissionen (Horisont 2020), 2015-01-01 -- 2019-01-01.

Styrkeområden

Transport

Energi

Ämneskategorier

Teknisk mekanik

Strömningsmekanik och akustik

Infrastruktur

C3SE (Chalmers Centre for Computational Science and Engineering)

DOI

10.1016/j.ijmultiphaseflow.2019.103191

Mer information

Skapat

2020-01-15