scholarly journals EFD and CFD Design and Analysis of a Propeller in Decelerating Duct

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Stefano Gaggero ◽  
Cesare M. Rizzo ◽  
Giorgio Tani ◽  
Michele Viviani
Keyword(s):  
Experimental Information ◽  
Optimization Techniques ◽  
Towing Tank ◽  
Radiated Noise ◽  
Successive Refinement ◽  
Numerical Predictions ◽  
Complex Evaluation ◽  
Cavitation Tunnel ◽  
Lifting Line ◽  
Numerical Approaches

Ducted propellers, in decelerating duct configuration, may represent a possible solution for the designer to reduce cavitation and its side effects, that is, induced pressures and radiated noise; however, their design still presents challenges, due to the complex evaluation of the decelerating duct effects and to the limited amount of available experimental information. In the present paper, a hybrid design approach, adopting a coupled lifting line/panel method solver and a successive refinement with panel solver and optimization techniques, is presented. In order to validate this procedure and provide information about these propulsors, experimental results at towing tank and cavitation tunnel are compared with numerical predictions. Moreover, additional results obtained by means of a commercial RANS solver, not directly adopted in the design loop, are also presented, allowing to stress the relative merits and shortcomings of the different numerical approaches.

Numerical Predictions and Experimental Verifications for the Hydrodynamic Performance of Horizontal Axis Marine Current Turbine

2013 ◽  
Vol 694-697 ◽  
pp. 635-638
Author(s):  
Rui Jun Fan ◽  
Hong Chao Gao ◽  
J. R. Chaplin
Keyword(s):  
Hydrodynamic Performance ◽  
Experimental Measurements ◽  
Hydrodynamic Conditions ◽  
Towing Tank ◽  
Numerical Predictions ◽  
Turbine Performance ◽  
Marine Current Turbine ◽  
Cavitation Tunnel ◽  
Marine Current ◽  
Current Turbine

This paper presents the numerical predictions of 3D CFD rotor computations of an 800mm diameter model of marine current turbine (MCT). In the paper CFD is applied to a rotor at stationary hydrodynamic conditions Simulations from the numerical prediction are compared with experimental measurements of the model of MCT which is experimented on in a cavitation tunnel and a towing tank. The experimental data includes measurements of power and thrust generated by the turbine, in both a cavitation tunnel and a towing tank, for a series of blade pitch settings and speeds. The numerical predictions show similar results and provide a satisfactory representation of the experimental turbine performance.

scholarly journals Comparison of numerical predictions of the supersonic expansion inside micronozzles of micro–resistojets

2019 ◽  
Vol 304 ◽  
pp. 02012
Author(s):  
Maria Grazia De Giorgi ◽  
Donato Fontanarosa ◽  
Antonio Ficarella
Keyword(s):  
Specific Impulse ◽  
Direct Simulation Monte Carlo ◽  
Operating Conditions ◽  
Rapid Expansion ◽  
Partial Slip ◽  
Navier Stokes ◽  
Numerical Predictions ◽  
Simulation Monte Carlo ◽  
Nitrogen Flows ◽  
Numerical Approaches

The present work provides a numerical investigation of the supersonic flow inside a planar micronozzle configuration under different gas rarefaction conditions. Two different propellants have been considered, namely water vapor and nitrogen, which relate to their use in VLMs (the former) and cold gas microthrusters (the latter), respectively. Furthermore, two different numerical approaches have been used due to the different gas rarefaction regime, i.e. the typical continuum Navier–Stokes with partial slip assumption at walls and the particle–based Direct Simulation Monte Carlo (DSMC) technique. As a result, under high–pressure operating conditions, both water and nitrogen flows supersonically expanded into the micronozzle without chocking in combination with a linear growth of the boundary layer on walls. However, when low–pressure operating condition are imposed and a molecular regime is established inside the micronozzle, a very rapid expansion occurred close to the nozzle exit in combination with a strong chocking of the flow and a micronozzle quality reduction of about 40%. Furthermore, water exhibited specific higher specific impulse than nitrogen above 60%.

Experimental and Numerical Studies on Super-Cavitating Flow of Axisymmetric Cavitators

2010 ◽  
Author(s):  
Byoung-Kwon Ahn ◽  
Hyoung-Tae Kim ◽  
Chang-Sup Lee
Keyword(s):  
Boundary Element Method ◽  
High Speed ◽  
Inviscid Flow ◽  
The Body ◽  
Cavitating Flows ◽  
Practical Advantage ◽  
Numerical Studies ◽  
Numerical Predictions ◽  
Cavitation Tunnel ◽  
National University

Recently underwater systems moving at high speed such as a super-cavitating torpedo have been studied for their practical advantage of the dramatic drag reduction. In this study we are focusing our attention on super-cavitating flows around axisymmetric cavitators. A numerical method based on inviscid flow is developed and the results for several shapes of the cavitator are presented. First using a potential based boundary element method, we find the shape of the cavitator yielding a sufficiently large enough cavity to surround the body. Second, numerical predictions of supercavity are validated by comparing with experimental observations carried out in a high speed cavitation tunnel at Chungnam National University (CNU CT).

Model Test of a Steel Catenary Riser in a Towing Tank

2009 ◽  
Author(s):  
Celso K. Morooka ◽  
Raphael I. Tsukada ◽  
Sergio da Silva ◽  
Ricardo Franciss ◽  
Cyntia G. C. Matt
Keyword(s):  
Model Test ◽  
Forced Oscillation ◽  
Cross Flow ◽  
Towing Tank ◽  
Steel Catenary Riser ◽  
Flow Response ◽  
Numerical Predictions ◽  
Steel Catenary Risers ◽  
Numerical Tools ◽  
Scr Model

The objective of the present work is the study of the dynamic behavior of steel catenary risers (SCRs), focusing on the contribution of vortex-induced vibration (VIV), through model test in a towing tank. Nowadays, a great deal of effort is being spent in order to better understand VIV’s contribution in the dynamics of riser structures through experiments, analytical analysis and numerical predictions. In the present work, the design of a SCR model test, along with its setup in a towing tank, will be described in detail and discussions of main results from the experiments will be presented. The experiment has been conducted under several simulated environmental condition combinations, varying the towing speed, riser top forced oscillation amplitudes, waves amplitudes and periods. Very promising results have been observed from the experiment. Riser oscillations due to high harmonics of vortex shedding were observed. Analysis of the experimental results, coupled with the support of numerical tools, showed the influence of the phenomena of traveling waves in the cross-flow response as is reported from the literature.

scholarly journals Manoeuvring forces on azimuthing podded propulsor model

2007 ◽  
Vol 14 (2) ◽  
pp. 3-8 ◽  
Author(s):  
Maciej Reichel
Keyword(s):  
Deflection Angle ◽  
Open Water ◽  
Ship Design ◽  
Experimental Results ◽  
Research Centre ◽  
Test Program ◽  
Towing Tank ◽  
Carrier Model ◽  
Podded Propulsor ◽  
Cavitation Tunnel

Manoeuvring forces on azimuthing podded propulsor model This paper presents the preliminary part of comprehensive manoeuvring open-water tests of a gas carrier model. The paper focuses on open water experiments with an azimuthing podded propulsor. The test program was carried out in the cavitation tunnel and the large towing tank of Ship Hydromechanics Division, Ship Design and Research Centre, Gdańsk. The pod was tested as a pushing unit with a 161.3 mm diameter propeller. Steering forces were measured in the range of advance coefficient from 0.0 to 0.8 combined with the range of deflection angles from -45° up to +45°. Measurements on the pod without propeller were also performed. The experiment results are presented in the form of non-dimensional coefficients in function of advance coefficient and deflection angle. Analysis of the experimental results and the conclusions are presented.

Experimental and Numerical Investigation of the Wave-Induced Loads on a Deep-V Catamaran in Regular Waves

2013 ◽  
Author(s):  
Musa B. Bashir ◽  
Longbin Tao ◽  
Mehmet Atlar ◽  
Robert S. Dow
Keyword(s):  
Wave Loads ◽  
Forward Speed ◽  
Regular Waves ◽  
Hull Form ◽  
Proper Understanding ◽  
Towing Tank ◽  
Centre Of Gravity ◽  
Numerical Predictions ◽  
New Research ◽  
Wave Induced

This paper presents the results of towing tank tests carried out to predict the wave loads in regular wave conditions on a Deep-V hull form catamaran model. The experiments were carried out at the Newcastle University towing tank using a segmented model of the university’s new research vessel, “The Princess Royal”. The vessel is a twin hull with a Deep-V shape cross-section. The model, divided into two parts at the cross-deck level, was fitted with a 5-axis load cell at the position of the vessel’s centre of gravity in order to measure the motions response and wave loads due to the encountered waves. The longitudinal, side and vertical forces, along with the prying and yaw splitting moments were measured. The results obtained were further compared with those from numerical predictions carried out using a 3D panel method code based on potential flow theory that uses Green’s Function with the forward speed correction in the frequency domain. The results highlight reasonable correlations between the measurements and the predictions as well as the need for a proper understanding of the response of the multihull vessels to the wave-induced loads due to the non-linearity that have been observed in the experimental measurements of wave loads.

scholarly journals Assessment of Cavitating Flow Aggressiveness on a Hydrofoil: Experimental and Numerical Approaches

2017 ◽  
Author(s):  
Jean-Bastien Carrat ◽  
Regiane Fortes-Patella ◽  
Jean-Pierre Franc
Keyword(s):  
Experimental Analysis ◽  
Cavity Length ◽  
Cold Water ◽  
Numerical Approach ◽  
Vapor Mixture ◽  
Cavitation Tunnel ◽  
Shedding Frequency ◽  
Unsteady Behavior ◽  
Good Agreement ◽  
Numerical Approaches

The aggressiveness of a partial cavity on a hydrofoil in a cavitation tunnel is investigated from a joint numerical and experimental analysis. The numerical approach is based on a homogeneous equilibrium model and a barotropic law for the liquid/vapor mixture [1, 2] for cold water. The unsteady behavior of the cavity appears in good agreement with experiments although the maximum cavity length is underestimated and the cloud shedding frequency overestimated. The flow aggressiveness is estimated by using the energy approach proposed by Fortes-Patella et al. [3, 4]. The technique predicts a maximum in flow aggressiveness located in the region where the cloud cavity is shed and increases as a power of the flow velocity between 2 and 3.

scholarly journals Design and Hydrodynamic Model Test of Mini Submarine Propeller with High Efficiency and Low Cavitation

2018 ◽  
Vol 1 (2) ◽  
pp. 59-64
Author(s):  
Mahendra Indiaryanto ◽  
Mohammad Ridwan Utina ◽  
Nurwidhi Asrowibowo ◽  
Siti Sadiah
Keyword(s):  
Traditional Method ◽  
Major Part ◽  
High Efficiency ◽  
Model Tests ◽  
Propulsive Efficiency ◽  
Good Efficiency ◽  
Towing Tank ◽  
Acoustic Signature ◽  
Surface Vessels ◽  
Cavitation Tunnel

Design and development of propellers for submarines are in some ways different from propellers for surface vessels. The most important demand is low acoustic signature and propeller efficiency. The design for the propulsor for submarine is a specialist task of a later  stage of design. The propulsive efficiency has essensially three parts in the traditional method of approach. The first and major part is the efficiency of the propeller it self as a divice which may develop to overcome the resistance to motion the vessel. The aim of this research is to design a mini submarine propeller and obtain high efficiency and low cavitation. To reach this aim, model tests were performed both in Towing Tank and Cavitation Tunnel.  From the propeller model tests, the result shows a good efficiency and low cavitation.   Keywords: Submarine , Propeller , Efficiency, Cavitation

scholarly journals Critical review of propeller performance scaling methods, based on model experiments and numerical calculations

2013 ◽  
Vol 20 (4) ◽  
pp. 71-79 ◽  
Author(s):  
Tomasz Bugalski ◽  
Heinrich Streckwall ◽  
Jan A. Szantyr
Keyword(s):  
Scale Effects ◽  
Theoretical Research ◽  
Research Centre ◽  
Towing Tank ◽  
Model Experiments ◽  
Performance Scaling ◽  
Cavitation Tunnel ◽  
Scaling Methods ◽  
Propeller Performance ◽  
New Procedures

ABSTRACT The article presents the results of experimental and numerical investigation of propeller scale effects, undertaken in co-operation of the Hamburg Ship Model Basin (HSVA), Germany, and Ship Design and Research Centre (CTO SA), Poland. The objective of the investigation was to test the adequacy of the methods currently used to account for the propeller scale effect and to develop possible improvement of the methods. HSVA has conducted model experiments in the large cavitation tunnel together with panel method and CFD calculations. CTO SA has performed model experiments in the towing tank, together with lifting surface and CFD calculations. Both institutions have suggested different new approaches to the problem and different new procedures to account for the propeller scale effects. In the article the procedures are presented together with the description of the underlying experimental and theoretical research.

Sign in / Sign up

Export Citation Format

Share Document