PENGARUH THRUST DEDUCTION FACTOR DAN WAKE FRACTION TERHADAP EFISIENSI PROPULSI AKIBAT PERUBAHAN DRAFT KAPAL

This study is to investigate propulsion efficiency due to changes in draught of ship using data series and theoretical approach. A hard chain rescue boat with triplet screw was used for the study and to examine the effect of thrust deduction factor and wake fraction due to changes in draught of ship and its relevance to propulsion efficiency by observing hull and propeller interaction based on openwater test by Wageningen Data Series with cavitations analysis has been neglected. The study is done using hydrodynamics analysis for planning hull and using intersection between thrust characteristic curve with openwater test data series for fixed pitch propeller. The result indicated that the changes in ship draught are very influential on the changes in thrust deduction factor and wake fraction value which is one of the contributing factor to change the propulsion efficiency value 1% - 5%.

“But When Are We Going to Learn the Real Do?” Toward Learner-Centered Pitch Practices in U.S. Music Classrooms

While the field of music education is rife with participation in methodological debates around “best systems” for learning about pitch, the authors in this article explore the possibilities of learner-centered approaches to teaching pitch among students with diverse music backgrounds. Specifically, the article highlights several challenges faced by the students with fixed pitch backgrounds in U.S. music classrooms: confusion around solfège syllables used to represent both movable and fixed pitch systems, and difficulty in transitioning between fixed and movable systems regardless of the symbolic language used. The authors offer a variety of research-based recommendations for deepening students' understandings of pitch in light of these challenges and emphasize the necessity for a learner-centered approach to pitch pedagogy in U.S. music classrooms. The purpose of this article is to (1) help practicing teachers understand more deeply and empathize with the nature of confusion students with fixed pitch backgrounds might experience in American music classrooms, and (2) develop pedagogical strategies that are sensitive to the experiences of these students while working to deepen understanding of pitch.

EXPERIMENTAL AND NUMERICAL EVALUATION OF PERFORMANCE OF A VARIABLE PITCH VERTICAL AXIS WIND TURBINE

The research work depicts the study of the comparison of a 1kW Fixed Pitch Vertical Axis Wind Turbine (VAWT) and a Variable Pitch VAWT via analytical, numerical and experimental results. Being an emerging technology, wind turbine is becoming a source of attraction for the researchers. The VAWT in comparison to the Horizontal Axis Wind Turbine (HAWT), has shown numerous benefits. The fundamental purpose of this work is to maximize the output power and output torque of the wind turbine. For achieving an improved output, a novel and unique mechanism, termed as pitching mechanism, is employed that follows the variable pitch concept. The mathematical modelling was done for the straight blade variable pitch VAWT as well as for the fixed rotor. The four bar mechanism was developed, to execute the variable pitch mechanism, and implemented in the form of the CAD model. A scaled down 3D Model of the rotor was manufactured using 3D printing technique. The aerodynamic forces such as lift and drag were measured upon the rotor as per the testing on the rotor in the wind tunnel. CFD simulations were run for the fixed pitch as well as the variable pitch rotor. The transient analysis was performed for the azimuthal angle ranging from 0 to 360 degrees and for a pitch angle varying from +25 to-25 degrees in ANSYS software. The comparative study was undertaken, keeping in view the analytical, simulation and experimental results. A worthy agreement was observed between analytical, software and experimental results and a promising increase in power and torque was observed due the introduction of the variable pitch mechanism. The power produced by the variable pitch design showed a significant increase in the power production as compared to the fixed pitch design. The numerical and experimental values of cp for the variable pitch design were quite comparable.

Improvement of mooring tests of main engine running to fixed pitch propeller

The most important stage in vessel’s construction is acceptance tests. By testing the main power plant of the vessel the design solutions adopted to ensure stable operation of the main engine and the propeller are checked. Such a check of the main engine according to design characteristics at the quay wall can significantly reduce sea trials cost. In practice, the peculiarities of the propeller operation at zero free-flow velocity at the quay wall limit the operating modes of the main power plant and the possibilities of mooring tests. There are considered the traditional and innovative simulation methods and tools used in mooring tests. The methods allow unloading the engine in terms of torque bringing its operation mode closer to the design parameters. An urgent scientific and technical problem has been solved to reduce the mechanical stress of the main engine, which operates according to the mooring characteristic on a fixed pitch propeller. The factors influencing the value of the resistance moment of the propeller at a zero vector of the incident flow are determined. Possible directions for improving the acceptance tests of the main power plant by supplying an additional environment, i.e. air to the suction surface of the propeller blade, are substantiated. In the complex of computational fluid dynamics, a computational model of a fixed pitch propeller has been created. The amount of air required to change the propeller operating mode has been estimated. Resistance moment of the propeller for various methods of air supply to the propeller has been analyzed. Additional means of controlling the main engine operating mode at the stages of the ship's life cycle are proposed.

Analysis of Influence of Tilt Angle on Variable-Speed Fixed-Pitch Floating Offshore Wind Turbines for Optimizing Power Coefficient Using Experimental and CFD Models

This study focused on optimization of the power coefficient of floating offshore wind turbines (FOWTs) to maintain their wind power performance in order to overcome problems with the tilt angle resulting from an unstable wind turbine platform, which can reduce the effective area of wind turbine energy extraction. FOWTs with a variable-speed fixed-pitch control strategy were investigated using an experimental model in a wind tunnel and a CFD simulation model for analysis and comparison, using wind speeds of 2–5.5 m/s and tilt angles of 3.5–6.1°. The results showed that average rotational speed differences of 16.4% and optimal power coefficients of 0.35–0.36 could be maintained at tip speed ratios of 7.7–9.6 during wind speeds of 3–5 m/s with tilt angles of 3.9–5.8°. The results of this study provide insights into a new concept of power coefficient optimization using variable tilt angle for small to medium fixed pitch FOWTs, to reduce the cost of pitch control systems.