scholarly journals Experimental Study on Dynamic Structure of Propeller Tip Vortex

2020 ◽  
Vol 27 (2) ◽  
pp. 11-18
Author(s):  
Li Guangnian ◽  
Qingren Chen ◽  
Yue Liu
Keyword(s):  
Dynamic Structure ◽  
Tip Vortex ◽  
Fluctuating Pressure ◽  
Tip Vortex Cavitation ◽  
Wake Field ◽  
Propeller Wake ◽  
Propeller Design ◽  
Piv Technique ◽  
Principal Source ◽  
Blade Tip

AbstractPropeller cavitation is a main source of fluctuating pressure and noise induced by propellers, and the tip vortex cavitation is the principal source. The present study measures the flow fields near the blade tip using the 2D-PIV technique. The experimental setup and scheme are introduced. We monitor the process of generation and shedding of the propeller tip vortex in real time and analyse the dynamic structure of the tip vortex by testing the propeller wake field under different phases of the axial plane. The distribution characteristics of radial and axial velocity are also analysed. The influence range and the vorticity of the tip vortex and trailing vortex are obtained. All of the measured quantitative data are useful for future propeller design.

scholarly journals The singing vortex

2015 ◽  
Vol 5 (5) ◽  
pp. 20150025 ◽  
Author(s):  
R. Arndt ◽  
P. Pennings ◽  
J. Bosschers ◽  
T. van Terwisga
Keyword(s):  
Dynamic Behaviour ◽  
Tip Vortex ◽  
Frequency Content ◽  
Tip Vortex Cavitation ◽  
Marine Propellers ◽  
Sheet Cavitation ◽  
Propeller Design ◽  
Research Article ◽  
Propeller Blades ◽  
Vortex Disturbances

Marine propellers display several forms of cavitation. Of these, propeller-tip vortex cavitation is one of the important factors in propeller design. The dynamic behaviour of the tip vortex is responsible for hull vibration and noise. Thus, cavitation in the vortices trailing from tips of propeller blades has been studied extensively. Under certain circumstances cavitating vortices have been observed to have wave-like disturbances on the surfaces of vapour cores. Intense sound at discrete frequencies can result from a coupling between tip vortex disturbances and oscillating sheet cavitation on the surfaces of the propeller blades. This research article focuses on the dynamics of vortex cavitation and more in particular on the energy and frequency content of the radiated pressures.

Modeling of Propeller Cavitation on Merchant Vessels

1982 ◽  
Vol 19 (01) ◽  
pp. 37-51
Author(s):  
Leslie M. Gray ◽  
David S. Greeley
Keyword(s):  
Input Data ◽  
Tip Vortex ◽  
Analytical Models ◽  
Time Varying ◽  
Massachusetts Institute ◽  
Massachusetts Institute Of Technology ◽  
Marine Propeller ◽  
Tip Vortex Cavitation ◽  
Propeller Design ◽  
Institute Of Technology

The time-varying cavitation on a marine propeller, which excites hull vibrations, is calculated. The analytical model is exercised to guide propeller design and operation in order to minimize this type of hull excitation. This model, as well as a more elaborate model under development at Massachusetts Institute of Technology, is compared with recent full-scale observations of propeller cavitation. The paper illustrates the importance of both accurate input data on scaled vessel wake velocities and the inclusion, in analytical models, of tip vortex cavitation.

Noise due to extreme bubble deformation near inception of tip vortex cavitation

2004 ◽  
Vol 16 (7) ◽  
pp. 2411-2418 ◽  
Author(s):  
Jin-Keun Choi ◽  
Georges L. Chahine
Keyword(s):  
Tip Vortex ◽  
Tip Vortex Cavitation ◽  
Bubble Deformation

Application of a Boundary Element Method in the Prediction of Unsteady Blade Sheet and Developed Tip Vortex Cavitation on Marine Propellers

2004 ◽  
Vol 48 (01) ◽  
pp. 15-30
Author(s):  
Hanseong Lee ◽  
Spyros A. Kinnas
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Pressure Fluctuations ◽  
Ship Hull ◽  
Tip Vortex ◽  
Tip Vortex Cavitation ◽  
Marine Propellers ◽  
Sheet Cavitation ◽  
Numerical Predictions ◽  
Element Method

Most marine propellers operate in nonaxisymmetric inflows, and thus their blades are often subject to an unsteady flow field. In recent years, due to increasing demands for faster and larger displacement ships, the presence of blade sheet and tip vortex cavitation has become very common. Developed tip vortex cavitation, which often appears together with blade sheet cavitation, is known to be one of the main sources of propeller-induced pressure fluctuations on the ship hull. The prediction of developed tip vortex cavity as well as blade sheet cavity is thus quite important in the assessment of the propeller performance and the corresponding pressure fluctuations on the ship hull. A boundary element method is employed to model the fully unsteady blade sheet (partial or supercavitating) and developed tip vortex cavitation on propeller blades. The extent and size of the cavity is determined by satisfying both the dynamic and the kinematic boundary conditions on the cavity surface. The numerical behavior of the method is investigated for a two-dimensional tip vortex cavity, a three-dimensional hydrofoil, and a marine propeller subjected to nonaxisymmetric inflow. Comparisons of numerical predictions with experimental measurements are presented.

Investigation of Helicopter Rotor-Blade-Tip-Vortex Alleviation Using a Slotted Tip

AIAA Journal ◽  
2004 ◽  
Vol 42 (3) ◽  
pp. 524-535 ◽  
Author(s):  
Yong Oun Han ◽  
J. Gordon Leishman
Keyword(s):  
Rotor Blade ◽  
Tip Vortex ◽  
Helicopter Rotor ◽  
Helicopter Rotor Blade ◽  
Blade Tip

Observation and Scaling of Tip Vortex Cavitation on Elliptical Hydrofoils

2011 ◽  
Author(s):  
Shigeki Nagaya ◽  
Risa Kimoto ◽  
Kenji Naganuma ◽  
Takayuki Mori
Keyword(s):  
Water Quality ◽  
Reynolds Number ◽  
High Speed ◽  
Tip Vortex ◽  
Video Observation ◽  
Tip Vortex Cavitation ◽  
Air Content ◽  
Sheet Cavitation ◽  
High Speed Video ◽  
Systems Research

Experimental study on tip vortex cavitation (TVC) was carried out for elliptical hydrofoils with various chord lengths. The purpose of the experiment was to clarify the influences of Reynolds number and water quality on tip vortex cavitation. Experiments were made in a large cavitation tunnel of the Naval Systems Research Center, TRDI/Ministry of Defense Japan. The elliptical hydrofoils tested were NACA 0012 cross section with chord lengths of 500mm, 250mm and 50mm. Reynolds number based on hydrofoil chord length was 2×105 < ReC < 7.4×106. Water quality of the tunnel was characterized by air content and nuclei distribution. Air content of the tunnel was varied between 30% and 80%. Nuclei distribution was measured by a cavitation susceptibility meter (CSM) with center-body venturi. Cavitation inception was determined from high speed video observation. A standard formula, (σL/σS) = (ReL/ReS)n, was applied for the scaling. In the present study, exponent of the scaling law n was found to be 0.2 < n < 0.4. High speed video observation showed that the process of the TVC inception strongly depends on water quality. In the experiments, unsteady behaviors of TVC were also investigated. Strong interactions between sheet cavitation and TVC were observed.

scholarly journals Full field assessment of wind turbine near wake deviation in relation to yaw misalignment

2016 ◽  
Author(s):  
Juan-José Trujillo ◽  
Janna K. Seifert ◽  
Ines Würth ◽  
David Schlipf ◽  
Martin Kühn
Keyword(s):  
Wind Turbine ◽  
Tip Vortex ◽  
Offshore Wind ◽  
Normal Operation ◽  
Offshore Wind Turbine ◽  
Near Wake ◽  
Thrust Coefficient ◽  
Full Field ◽  
Wake Field ◽  
Partial Load

Abstract. Presently there is a lack of data revealing the behaviour of the path followed by the near wake of full scale wind turbines and its dependence on yaw misalignment. Here we present an experimental analysis of the horizontal wake deviation of a 5 MW offshore wind turbine between 0.6 and 1.4 diameters downstream. The wake field has been scanned with a short range lidar and the wake path has been reconstructed by means of two-dimensional Gaussian tracking. We analysed the measurements for rotor yaw misalignments arising in normal operation and during partial load, representing high thrust coefficient conditions. We classified distinctive wake paths with reference to yaw misalignment, based on the nacelle wind vane, in steps of 3° in a range of ±10.5°. All paths observed in the nacelle frame of reference showed a consistent convergence towards 0.9 rotor diameters downstream suggesting a kind of wake deviation delay. This contrasts with published results from wind tunnels which in general report a convergence towards the rotor. The discrepancy is evidenced in particular in a comparison which we performed against published paths obtained by means of tip vortex tracking.

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