scholarly journals CFD Analysis on Propeller Performance with Propeller Boss Cap Fin

2019 ◽  
Vol 8 (4) ◽  
pp. 9516-9521
Keyword(s):  
Open Water ◽  
Developed Countries ◽  
Design Parameters ◽  
Propeller Wake ◽  
Water Test ◽  
Shaft Torque ◽  
Dynamic Meshing ◽  
Propeller Performance ◽  
Fuel Consumption And Emissions ◽  
Developing And Developed Countries

The global price of oil, which is both finite and limited in quantity, has been rising steadily because of the increasing requirements for energy in both developing and developed countries. Furthermore, regulations have been strengthened across all industries to address global warming. Many studies of hull resistance, propulsion and operation of ships have been performed to reduce fuel consumption and emissions. The present study examined the design parameters of the propeller boss cap fin (PBCF) and hub cap in improving the propeller efficiency. PBCF is the kind of hydrodynamic energy saving device which aims to reduce energy losses associated with propeller hub vortex by fitting fins to the cap of a propeller. The main principles of PBCF is breaking up hub vortex to straighten propeller wake, thus recovering the negative pressure on the cap. This reduces propeller’s rotational losses and produces negative torque to reduce propeller shaft torque and generating thrust. The study focuses on the size of the blades on boss cap and optimizing its geometry using CFD technique. Open Water Test has been modelled using dynamic meshing technology known as overset meshing. Seven variations of PBCF are modelled and tested to estimate the efficiency of the propeller. The obtained results are then compared with the simulation result with the propeller without PBCF arrangements. The propeller characteristics (without PBCF) has been initially validated using overset meshing strategy with the available experimental results. Overset mesh has been used to perform this analysis to give better control over the fluid flow. It has been observed that, the propeller with PBCF, one among seven variations is giving nearly 2.0% more efficient than the propeller without PBCF.

Numerical analysis of ducted propeller performance under open water test condition

2013 ◽  
Vol 18 (3) ◽  
pp. 381-394 ◽  
Author(s):  
Long Yu ◽  
Martin Greve ◽  
Markus Druckenbrod ◽  
Moustafa Abdel-Maksoud
Keyword(s):  
Numerical Analysis ◽  
Open Water ◽  
Ducted Propeller ◽  
Water Test ◽  
Propeller Performance

scholarly journals Design of Propeller Series Optimizing Fuel Consumption and Propeller Efficiency

2021 ◽  
Vol 9 (11) ◽  
pp. 1226
Author(s):  
Mina Tadros ◽  
Manuel Ventura ◽  
Carlos Guedes Soares
Keyword(s):  
Fuel Consumption ◽  
Fitness Function ◽  
Open Water ◽  
Design Tool ◽  
Design Parameters ◽  
Propeller Design ◽  
Water Conditions ◽  
Calm Water ◽  
Propeller Performance ◽  
Propeller Geometry

This paper presents a comparison between different types of propellers operated in calm water to evaluate their performance behind hulls and in open-water conditions. A bulk carrier is chosen as a case study to perform the simulation and to evaluate the performance of several propeller series, namely the Wagengein B-series, Kaplan 19A, and MAU. Firstly, optimization procedures are performed by coupling a propeller design tool and a nonlinear optimizer to find the optimum design parameters of a fixed-pitch propeller. This optimization model aims to design the propeller behind the hull at the engine operating point with minimum fuel consumption and maximum propeller efficiency. The two main objectives of this study and the constraints are defined in a single fitness function to find the optimum values of the propeller geometry and the gearbox ratio. By considering the benefits of the single-objective over the multi-objective optimization problem, this model helps to find the optimum propeller for both defined objectives instead of only considering one of them, as in previous studies. Then, based on the optimized parameters, the propeller performance is calculated in open-water conditions. From the computed results, one can observe the importance of considering the hull–propulsor interaction in propeller selection.

Parametric Study on Hub Vortex Reducing Effects of Propeller Boss Cap Fins by Force and Wake Field Measurements in Open Water and Self-Propulsion Conditions

2016 ◽  
Author(s):  
Jeonghwa Seo ◽  
Bumwoo Han ◽  
Shin Hyung Rhee ◽  
Seung-Jae Lee ◽  
Hyeseong Kim ◽  
...  
Keyword(s):  
Force Measurement ◽  
Field Measurements ◽  
Open Water ◽  
Stereoscopic Particle Image Velocimetry ◽  
Design Parameters ◽  
Total Efficiency ◽  
Wake Field ◽  
Propeller Wake ◽  
Global Force ◽  
Measurement Results

Propeller boss cap fins (PBCF) is one of the most popular ESDs in the industry. The present study aims to investigate effects of design variations of PBCFs on the propulsive efficiency and propeller wake field, with special attention on hub vortex dynamics. The wake fields and force on the whole propulsive system were measured by a towed underwater stereoscopic particle image velocimetry (SPIV) system and a propeller open water (POW) test dynamometer, respectively. Design parameters of PBCFs, i.e., the fin surface area and the angle of attack onto the fins, were varied to control fin loading on the PBCF. In the wake field, root vortices generated from the propeller blades were separated by PBCF and did not form a strong hub vortex, which caused pressure drop on the propeller boss cap. The hub vortex reduction practically increased total thrust, as evidenced in the global force measurement results. In PBCF design variations, Total efficiency increased linearly as the pitch angle and fin chord length decreased. The global force measurement results implied that PBCF in light loading separated root vortices efficiently. Hub vortex reduction by PBCF in light loading was also confirmed by the wake field measurement. In the case of low fin height, however, root vortices were not blocked and actually merged to form a hub vortex. Therefore, the primary function of PBCF, i.e., reducing hub vortex, was not effective anymore and the total efficiency decreased. In heavy loading conditions, axial velocity near the center retarded further, causing greater drag and diminishing the total efficiency. The model tests were also conducted in self propulsion condition, to reveal that the new PBCF with reduced loading also improves the energy saving performance when it works in the wake of the ship.

Housing Inflation: Policy Guidelines from Shariah Perspective

2019 ◽  
Vol 16 (1) ◽  
pp. 70-81
Author(s):  
Azrul Azlan Iskandar Mirza ◽  
Asmaddy Haris ◽  
Ainulashikin Marzuki ◽  
Ummi Salwa Ahmad Bustamam ◽  
Hamdi Hakiem Mudasir ◽  
...  
Keyword(s):  
Content Analysis ◽  
Housing Prices ◽  
Construction Materials ◽  
Housing Price ◽  
Developed Countries ◽  
Control Element ◽  
Recent Issue ◽  
Analysis Methodology ◽  
The Government ◽  
Developing And Developed Countries

The soaring housing prices in Malaysia is not a recent issue. It is a global phenomenon especially in developing and developed countries, driven by factors including land price, location, construction materials cost, demand, and speculation. This issue demands immediate attention as it affects the younger generation, most of whom could not afford to buy their own house. The government has taken many initiatives and introduced regulations to ensure that housing prices are within the affordable range. This article aims to introduce a housing price control element from the Shariah perspective, as an alternative solution for all parties involved in this issue. It adopts content analysis methodology on policy from Shariah approved sources.

Recent Developments in Computational Methods for the Analysis of Ducted Propellers in Open Water

2019 ◽  
Vol 63 (4) ◽  
pp. 219-234
Author(s):  
João Baltazar ◽  
José A. C. Falcão de Campos ◽  
Johan Bosschers ◽  
Douwe Rijpkema
Keyword(s):  
Computational Methods ◽  
Open Water ◽  
Boundary Element Methods ◽  
Navier Stokes ◽  
Hydrodynamic Analysis ◽  
Numerical Predictions ◽  
Ducted Propeller ◽  
Recent Developments ◽  
Propeller Performance ◽  
Ducted Propellers

This article presents an overview of the recent developments at Instituto Superior Técnico and Maritime Research Institute Netherlands in applying computational methods for the hydrodynamic analysis of ducted propellers. The developments focus on the propeller performance prediction in open water conditions using boundary element methods and Reynolds-averaged Navier-Stokes solvers. The article starts with an estimation of the numerical errors involved in both methods. Then, the different viscous mechanisms involved in the ducted propeller flow are discussed and numerical procedures for the potential flow solution proposed. Finally, the numerical predictions are compared with experimental measurements.

scholarly journals Income, wealth and use of personal protection equipment in the Mekong Delta

2021 ◽  
Author(s):  
Matteo Migheli
Keyword(s):  
Low Income ◽  
Mekong Delta ◽  
Developed Countries ◽  
Household Wealth ◽  
Protective Equipment ◽  
Personal Protection ◽  
Personal Protection Equipment ◽  
Management Techniques ◽  
Using Data ◽  
Developing And Developed Countries

AbstractBoth in developing and developed countries, farmers often do not protect themselves adequately, especially when applying agrochemicals that are dangerous for their health. The issue is relevant because insufficient protection is between the causes leading to intoxication of farmers and workers who handle these products. The literature suggests that both lack of training and information and low income may explain why, especially in developing countries, protective equipment is under-used. Using data from the Mekong Delta, this study addresses the issue of whether income and household wealth may help explaining the use of incomplete protections against pesticides. The results suggest that income, more than wealth, is a reason why Vietnamese farmers operating in the Mekong Delta fail in using adequate protections. In particular, the data suggest that they may prefer to divert resources to increasing the production of their fields or to buying goods that may be used both as protection and as everyday garments. This behaviour leads to underinvestment in some important protective goods. Possible public interventions to mitigate the problem are suggested; in particular, the promotion of integrated pest management techniques could be useful.

scholarly journals Strategies for reducing out of pocket payments in the health system: a scoping review

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Faride Sadat Jalali ◽  
Parisa Bikineh ◽  
Sajad Delavari
Keyword(s):  
Health System ◽  
Health Systems ◽  
Scoping Review ◽  
Health Financing ◽  
Developed Countries ◽  
Vulnerable Groups ◽  
System A ◽  
Out Of Pocket Payments ◽  
Review Study ◽  
Developing And Developed Countries

Abstract Background Direct out-of-pocket payments (OOP) are among the most important financing mechanisms in many health systems, especially in developing countries, adversely affecting equality and leading vulnerable groups to poverty. Therefore, this scoping review study was conducted to identify the strategies involving OOP reduction in health systems. Methods Articles published in English on strategies related to out-of-pocket payments were Searched and retrieved in the Web of Science, Scopus, PubMed, and Embase databases between January 2000 and November 2020, following PRISMA guidelines. As a result, 3710 papers were retrieved initially, and 40 were selected for full-text assessment. Results Out of 40 papers included, 22 (55%) and 18 (45%) of the study were conducted in developing and developed countries, respectively. The strategies were divided into four categories based on health system functions: health system stewardship, creating resources, health financing mechanisms, and delivering health services.As well, developing and developed countries applied different types of strategies to reduce OOP. Conclusion The present review identified some strategies that affect the OOP payments According to the health system functions framework. Considering the importance of stewardship, creating resources, the health financing mechanisms, and delivering health services in reducing OOP, this study could help policymakers make better decisions for reducing OOP expenditures.

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