Full Scale Measurements and Flow Analysis on a High Speed Rescue/Patrol Boat

2015 ◽  
Author(s):  
Hans Jørgen Mørch ◽  
Thomas Larsen ◽  
Erik Mostert ◽  
Karl Marius Norschau ◽  
Gunnar Semb
Keyword(s):  
High Speed ◽  
Cfd Simulation ◽  
Flow Analysis ◽  
Full Scale ◽  
Limiting Factor ◽  
Safe Operation ◽  
Cfd Simulations ◽  
Measurement Results ◽  
Calm Water ◽  
Operational Envelope

Through use of state of the art tools for flow analysis the aims to establish a methodology to determine the performance of a high speed planing craft both in calm water and in waves. Verification against full scale measurements is conducted. The ability to maintain speed in waves is of great interest -both with respect to added resistance and with respect to safe operation and loads on the crew from accelerations. Full scale measurements and CFD (Computational Fluid Dynamics) were conducted on a Norsafe Magnum 850fast patrol boat. The measurements have been conducted during a boat challenge along the Iberian coast. The challenge was run in advance of the HSBO (High Speed Boat Forum) which was held in Lisbon, Portugal, May2015.CFD simulations at similar conditions to the measurements are used for validation. It is further shown how CFD can be used to expand operational envelopes beyond the point where full scale measurements are applicable. This is especially relevant for the acceleration loads on the crew which is often the limiting factor of small HSC (High Speed Crafts). Pressure loads are extracted from the CFD and are evaluated against the current standards for life boats. Various criteria are discussed and the most relevant are analyzed for the measurement results and the CFD simulation. An operational envelope where the different criteria are combined is suggested.

An Overview of Stepped Hull Performance Evaluation: Sea Trial Data vs Full-Scale CFD Simulation

2020 ◽  
Author(s):  
Luigi Vitiello ◽  
Simone Mancini ◽  
Rasul Niazmand Bilandi ◽  
Vincenzo Nappo
Keyword(s):  
Performance Evaluation ◽  
High Speed ◽  
Cfd Simulation ◽  
Experimental Tests ◽  
Trial Data ◽  
Full Scale ◽  
Cfd Simulations ◽  
Sea Trial ◽  
Comparison Of The Results ◽  
Real Scale

It is well known that the dynamic of the stepped hull in real scale is rather complex and it’s not easy to predict that using empirical or mathematical approaches, and by the numerical and experimental way as well. Moreover, there is a huge lack in the literature of data related to sea trials of the stepped hull. Furthermore, the reliability of full-scale CFD simulations is not widely proven and validated especially for high speed and planing hull. For these several reasons, in this paper, the authors are focused on the comparison of the results carried out from model experimental tests performed in the model basin, full-scale CFD simulations, and sea trial tests. The performed simulations in full-scale have been compared to the extrapolated experimental tests and the sea-trial results. Moreover, the dynamic trim angle and the dynamic wetted surface have been taken into account to assess the reliability of the full-scale simulation performed. The stepped hull considered is a Mito 31 outboard Rigid Inflatable Boat (RIB) built by MV Marine Srl Company.

scholarly journals Design and Flow Analysis of an Adjustable Check Valve by Means of CFD Method

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2237
Author(s):  
Grzegorz Filo ◽  
Edward Lisowski ◽  
Janusz Rajda
Keyword(s):  
Cfd Simulation ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Check Valve ◽  
The Body ◽  
Cfd Simulations ◽  
Valve Body ◽  
Main Research ◽  
Flow Channels ◽  
Simulation Results

The article presents results of research on an adjustable check valve. In particular, the article deals with improvement of flow characteristics and reduction in pressure losses of an existing valve design. The subject of the research was the valve body in the form of a steel block intended for mounting a typical cartridge valve insert. Two variants of the valve body were analysed: a standard one, which is currently in production, and the proposed new solution, in which the geometry was modified based on the results of CFD simulations. The main research task was to properly shape and arrange holes and flow channels inside the body, between the cartridge valve and the connecting plate. Using CFD analyses, a solution for minimising the flow resistance was sought and then the method of modifying flow channels geometry was developed. The CFD simulation results showed a significant reduction in pressure loss, up to 40%. The obtained simulation results were verified on a test bench using a prototype of the proposed valve block. A high degree of consistency in the results of CFD simulations and laboratory experiments was achieved. The relative difference between simulation and experimental results in the entire considered range of the flow rate did not exceed 6.0%.

Design of a High Speed Internal Gear Pump to Increase the Power Density of Electro Hydraulic Actuators (EHA) in Mobile Applications

2019 ◽  
Author(s):  
Tobias Pietrzyk ◽  
David Roth ◽  
Georg Jacobs ◽  
Schmitz Katharina
Keyword(s):  
High Speed ◽  
Cfd Simulation ◽  
Mechanical Efficiency ◽  
Gear Pump ◽  
Suction Pressure ◽  
Shaft Seal ◽  
Test Rig ◽  
Cfd Simulations ◽  
Internal Gear ◽  
High Suction

Abstract Increasing the rotational speed of the internal gear pump entails addressing topics such as cavitation, overheating and filling problems of the tooth spaces. Besides the development of a tooth geometry and flow optimization, using CFD simulation is necessary. This paper discusses the design of the newly developed high speed internal gear pump. This includes a detailed description of the different parts as well as the dimensioning of the pump by using CFD simulations. The geometry of the pressure build-up groove has a significant effect of pressure build up inside the pump. Therefore, three different geometries are investigated. The calculation of the journal bearings for the internal gear as well as for the driving shaft is shown. To avoid cavitation problems, the suction pressure of the pump will be increased up to 25 bar. This paper will show the technical arrangements to reach this high suction pressure level whilst still using a radial shaft seal ring. In order to determine the efficiency of the newly developed high speed pump, a test rig was built up. The test rig allows the measurement of the volumetric efficiency as well as the hydraulic-mechanical efficiency at different operation points up to 10 000 rpm and 250 bar.

CFD Simulations of Lifeboat During Sailing Phase in Harsh Weather

2015 ◽  
Author(s):  
Vidar Tregde ◽  
Sverre Steen
Keyword(s):  
Degrees Of Freedom ◽  
Free Fall ◽  
Model Tests ◽  
Full Scale ◽  
Cfd Simulations ◽  
Thrust Coefficient ◽  
Cfd Models ◽  
Calm Water ◽  
Set Up ◽  
Full Scale Tests

A free fall lifeboat is going through several phases during a drop; sliding on the skid, rotation on skid, free fall, water entry, ventilation, maximum submergence, resurfacing and the sailing phase. In the sailing phase, the engine is running, providing propeller thrust, and the vessel is exposed to wind and waves while trying to run away from the host. CFD simulations of the lifeboat in the sailing phase have been run in regular Stokes 5th order waves, as well as simulations in irregular seas. The regular waves have been set up with different wave heights and wave periods. The set-up of waves have been done to fulfil the requirements in DNV-OS-E406, which is the DNV-GL offshore standard for design of free fall lifeboats. Validation of the CFD models are done with comparison to model tests from calm water tests as well as self-propelled model tests in waves. Results from full scale tests in calm water and in waves are also used in validation of CFD results. The hydrodynamic problem solved for 3 degrees-of-freedom (DOF) free running model in waves with thrust force from propeller is solved using the CFD software Star CCM+. A method for estimating thrust coefficient with a combination of full scale calm water results and results from CFD simulations is presented. The CFD simulations have shown to give acceptable accuracy for lifeboat in a seaway. Further, the CFD simulations have shown to be very useful for demonstrating fulfilment of requirements in the offshore standard for lifeboats in the sailing phase.

Scale Effects on Ship Maneuverability Using RANS

2018 ◽  
Author(s):  
Motoki Araki
Keyword(s):  
Cfd Simulation ◽  
Scale Effects ◽  
Full Scale ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Ship Maneuvering ◽  
Ship Maneuverability ◽  
Computational Fluid Dynamics Cfd ◽  
Rudder Angle ◽  
Maneuvering Simulations

Predicting ship maneuverability is one of the important topics in ship engineering. However because of the huge difference between model and full scale Reynolds number (Re), it is almost impossible to predict full scale ship maneuverability using conventional methods such as model test. On the other hands, with the developments of computational technologies and computational fluid dynamics (CFD) techniques, CFD simulations are widely applied on ship maneuvering problems (e.g. Stern et al., 2011). Moreover some of the researchers start the CFD simulation with full scale Re especially on propulsion problems (e.g. Tezdogan et al., 2015) which showing reasonable results. Therefore, in this paper, captive maneuvering simulations (rudder angle test) in model/full scale Re on KVLCC2 are carried out using Reynolds-averaged Navier–Stokes (RANS) solver NAGISA (Ohashi et al., 2014) with the overset gird method UP_GRID (Kodama et al., 2012). And the results between model and full scale simulations are compared in maneuvering coefficients and flow field to reveal the scale effect on ship maneuverability.

CFD Simulation for the Resistance Performance of 1000 Dwt Deep-Vee Vessels on Bulbous Bow

2011 ◽  
Vol 480-481 ◽  
pp. 288-293
Author(s):  
Yi Xie ◽  
Hua Zhao ◽  
Xiao Bin Fan ◽  
Hua Jun Jian
Keyword(s):  
High Speed ◽  
Cfd Simulation ◽  
Influence Factor ◽  
Influence Factors ◽  
Calm Water ◽  
Two Phases ◽  
Bulbous Bow ◽  
Rng Turbulence Model ◽  
Resistance Performance ◽  
Fraction Method

Resistance influence factors of bulbous bow are analyzed with three 1000dwt displacement types Deep-vee forms provided. The free surface viscous flow of these forms is calculated by air-water two phases RANS equations with RNG turbulence model and volume of fraction method. Total resistance, pressure distribution and wave profile of hull are presented. Some results can be taken as follows: Adopted longer protruding length can improve the resistance character at medium high speed and ameliorate the resistance performance in calm water at low speed to design a 1000dwt deep-vee vessel; the bulbous bow wavemaking is only one of the reasons to influence the wavemaking resistance of hull. The importance influence factor of hull wavemaking resistance is how to form advantage disturbance or least disadvantage disturbance between the bulbous bow wave and hull wave.

Flow Analysis and Assessment of Loss Models in the Symmetric Volute of a Turbo-Blower

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
Semi Kim ◽  
Junyoung Park ◽  
Bumseok Choi ◽  
Jehyun Baek
Keyword(s):  
Cfd Simulation ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Cfd Simulations ◽  
Turbo Blower ◽  
Mass Flow Rates ◽  
Computational Fluid Dynamics Cfd ◽  
Loss Coefficients ◽  
Simulated Flow

The objectives of the present study were to investigate the flow structure and assess the accuracy of loss correlations in the symmetric volute of a turbo-blower using 3D steady flow analysis methods. To accurately model the flow field in the volute, an impeller with a single blade, a diffuser with 13 vanes, and a volute were used as the calculation domains for the computational fluid dynamics (CFD) simulations. Numerical results were validated by comparison with experimental results for the performance of a turbo-blower operated under three operating conditions: high (0.38 kg/s), normal (0.3 kg/s), and low (0.23 kg/s) mass flow rates. The accuracy of the loss correlation sets reported in four previous studies was compared with the CFD simulation predictions. These comparisons showed that the correlation sets did not accurately represent the total pressure loss in the symmetric volute of a turbo-blower, and a modified correlation set that included adjustments for the loss coefficients was proposed. Detailed investigations of the simulated flow fields were compared to understand the flow characteristics in the volute under the designed operating conditions.

Numerical Study on the Effect of Stern Flap for Hydrodynamic Performance of Catamaran

2019 ◽  
Author(s):  
Peng Zhou ◽  
Liwei Liu ◽  
Lixiang Guo ◽  
Qing Wang ◽  
Xianzhou Wang
Keyword(s):  
High Speed ◽  
Cfd Simulation ◽  
Numerical Study ◽  
Experimental Studies ◽  
Hydrodynamic Performance ◽  
Flow Solver ◽  
Calm Water ◽  
Unsteady Simulation ◽  
Ship Hydrodynamic ◽  
Simulation Results

Abstract This paper presents CFD simulation results of the stern flap effect with different lengths for hydrodynamic performance of catamaran moving in calm water, including resistance and sailing attitude. Inhouse viscous CFD (computational fluid dynamics) code HUST-Ship (Hydrodynamic Unsteady Simulation Technology for Ship) is used for the study. The catamaran with/without stern flap with different lengths were studied. The trim and sinkage of the catamaran were solved coupled with flow solver. Experimental studies in calm water were conducted to validate the numerical method. The comparison of hydrodynamic performance of catamaran with stern flaps of different lengths was made. The results show that the stern flap can reduce the sailing attitude and has influence for the resistance of catamaran at high-speed.

CFD Simulation of Resistance of Highspeed Trimaran Hullforms

2015 ◽  
Author(s):  
Changhwan Son ◽  
Prasanta K. Sahoo ◽  
Vaibhav Aribenchi ◽  
Srikanth Asapana
Keyword(s):  
High Speed ◽  
Cfd Simulation ◽  
Accurate Determination ◽  
Cfd Analysis ◽  
Test Results ◽  
Ansys Fluent ◽  
Speed Range ◽  
Calm Water ◽  
Hull Forms

This paper attempts to carry out a CFD analysis on total resistance for trimaran hull forms based on established NPL systematic series which are high-speed round bilge hull forms. The resistance of high-speed trimaran hull forms have been determined using ANSYS FLUENT, a CFD software package. A systematic series of round bilge demi-hulls were generated, and their resistance in calm water were determined by using ANSYS FLUENT to briefly examine nature and degree of reliability of ANSYS FLUENT. The primary aim of this investigation is to determine resistance characteristics of slender round bilge trimaran hull forms in the high-speed range corresponding to Froude numbers up to 1.0. Model test results obtained from the paper Molland et al (1994) have been used to verify the efficacy of the CFD analysis. The results obtained from CFD have shown considerable promise and further analysis need to be carried out for accurate determination of resistance in trimaran configuration.

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