Controllable Pitch Research Articles

Study of Angle Control on Double Micro Emitter

At the base of development of ordnance, the study of model machine of controllable micro emitter definitive direction angle and pitch angle is advancing, which definitive direction angle and emissive angle is very important. By theoretical and empirical equation analysis, it may deduce dynamics equations about load flux of micro fluid controlling direction angle and emissive angle in micro emitter. After linearization, transfer function may be calculated. When deviation is very small, output and input control present good linear relation. So make emissive process control easy.

Design and Simulation of Bi-Directional Hydraulic Lock Used in Hydraulic System for Controllable Pitch Propeller

This paper designs a bi-directional hydraulic lock used in a large flow hydraulic system for controllable pitch propeller. The lock is used to resist the hydraulic cylinder shifting when the pitch reaches the presetting situation. The structure parameters of the lock are obtained by static design, and the dynamic performance of it is analyzed by modeling and simulation with the system on rated load. The dynamic simulating discovers the faults of the lock designing by static calculating and the results provide sufficient supports for its parameters optimization.

Design and Analysis of a Two-Valve Control Hydraulic System for Controllable Pitch Propeller

This paper designs a two-valve control hydraulic system for controllable pitch propeller which consists of an electro-hydraulic directional control valve and a proportional directional control valve. The parallel control strategy is proposed and respective controllers are determined for the system. It yields out the relationship between the control parameters and valves characteristics by modeling and simulation analysis. Also the influence of the proportional valve flow rate on pitch control accuracy is discussed.

入門コーナー「フィンスタビライザー」・「可変ピッチプロペラ」

入門コーナー「フィンスタビライザー」・「可変ピッチプロペラ」

The Investigation of Turbine Engine in Aspect of Output Torque Control

In the process of the routine exploitation of naval gas turbine the most important, for the exploiter, is the nature of the cooperation between the engine and its power receiver. In particular, if it is a controllable pitch propeller. Due to the fact that ship's documentation does not often contain that type of characterization, there was an attempt to its designation. Given the preliminary nature of the research, it was decided to perform them on gas turbine engine GTD-350. Appointment of a mathematical model of the above characteristics is a complex issue, requiring the application of the theory of planning experiments. The article demonstrates how to implement the preliminary tests and their results, the results of statistical analysis and substantive research results obtained and formulated on the basis of their conclusions.

(Invited) III-Nitride Nanowires: Emerging Materials for Lighting and Energy Applications

The aligned growth of III-nitride nanowires, along with results providing insights into the nanowire properties obtained using electrical, optical and structural characterization techniques, are discussed. A new "top-down" approach for fabricating ordered arrays of high quality GaN-based nanorods with controllable height, pitch and diameter is also presented, along with results from preliminary LEDs grown on these nanorod arrays. Additionally, a novel application of aligned nanowire arrays as strain-relief templates for the growth of high quality GaN is demonstrated.

Hydrodynamic Analysis of a Horizontal Axis Marine Current Turbine With a Boundary Element Method

A low order potential based panel code is used to analyze the flow around the blades of a horizontal axis marine current turbine. An empirical vortex model is assumed for the turbine wake, which includes the variation of pitch of the helicoidal vortices trailing behind the blades. The analysis is carried out for uniform inflow conditions in steady flow for a turbine with controllable pitch for two different pitch settings in a wide range of tip-speed-ratios. Grid convergence studies carried out to verify the accuracy of predicted pressure distributions and integrated forces show a fast convergence with grid refinement for this geometry. The effect of the helicoidal wake model parameters used in the analysis is found to have a strong influence in the performance curves. The results are compared with experimental data from literature and with the lifting line theory. A discussion of viscous effects is also provided to help explaining the main discrepancies with the data.

Energy performance evaluation of fishing vessels by fuel mass flow measuring system

A new fuel consumption monitoring system was set up for research purpose in order to evaluate the energy performance of fishing vessels under different operating conditions. The system has been tested on two semi-pelagic pair trawlers in the Adriatic Sea with an engine power of around 900 kW, and with length overall of around 30 m. Both vessels work with a gear of similar design and size, the differences between the two vessels are in the propeller design and the hull material: the first with a controllable pitch propeller (CPP) and a metal hull, the second with a fixed pitch propeller (FPP) and a wooden hull. The fuel monitoring system conceived at CNR-ISMAR Ancona (Italy) consists of two mass flow sensors, one multichannel recorder and one GPS data logger. The working time duration, the vessel speed, the total fuel consumption and the instant fuel rate were logged by the system. A typical commercial round trip for a semi-pelagic trawler consists of several fishing operations (steaming, trawling sailing, etc.). Fuel consumption rate and vessel speed data were used to identify energy performance under different vessel-operating conditions. The highest fuel demands were during the trawling (130 l/h at 4.4 kn) and the steaming (100–130 l/h at 11 kn) phases. Fuel savings of up to 15% could be obtained by reducing the navigation speed of half a knot.

The modeling of single-boat, mid-water trawl systems for fishing simulation

A mathematical model of single-boat, mid-water trawl system, together with a graphical interface have been created for training purposes. The model consists of separate components for the trawler and fishing gear. The trawler component considers the influence of wind and current and can be used to simulate trawlers in ordinary-speed and low-speed scenarios. The fishing gear component considers the towing warp, the otter board, and the fishing net. The model components are connected by coordinating boundary conditions. All trawling processes, including cruising, towing, and hauling and deploying the fishing net, can be simulated using this approach. Simulations have been undertaken based on a single-boat, mid-water trawler. The simulated trawler speed and turning circle under cruising conditions were compared to sea trials, and simulated trawl mouth height and trawl resistance to flume experiments. The hydrodynamic performance of a single-boat, mid-water trawl has been analyzed, showing that trends in fishing gear parameters together with towing speed and warp length are intuitively correct, but trawling speed is overestimated, which requires that the model component for the controllable pitch propeller be improved.

Adjustable twisting periodic pitch of amyloid fibrils

We present compelling experimental evidence supported by theoretical arguments demonstrating that the periodic twisting pitch in protein amyloid fibrils arises from the fine balance between competing electrostatic energy and torsional elastic energy stored along the fibrils contour length. To construct the present picture we have used increasing ionic strengths to progressively screen the electrostatic interactions and observed the corresponding pitch variations in mature β-lactoglobulin amyloid fibrils using single-molecule atomic force microscopy (AFM). Because the ionic strength is changed afterfibrils formation, this does not affect the mechanism by which fibrils grow up to their mature structure. For each individual population of the multi-stranded fibrils family, the pitch is found to increase systematically with the salt content, leading to the gradual untwisting of the fibrils and to the establishment of a controllable pitch up to virtually infinite values.

Modeling and Performance Analysis of Combined-Cycle Based Ship Power Plant

For combined-cycle power plant performance analysis, a ship power plant mathematical model is developed, including diesel engine, controllable pitch propeller, exhaust gas boiler, turbine generator and shaft generator models. The simulation performance characteristic curves of diesel engine under various loads are given. Comparison of simulation results and experimental data shows the model can well predict the performance of diesel engine in various operating conditions. The specific fuel oil consumption contours of combined-cycle power plant and the relations between engine operating conditions and steam cycle parameters are given. The influence of diesel engine operating conditions to the overall performance of combined-cycle power plant is discussed.

Study on Heavy CNC Belt Grinding Technology of High Precision Controllable Pitch Propeller

A high-precision grinding method is presented to the marine controllable pitch propeller. Developed the four-axis simultaneous grinding system based on the abrasive belt grinding principle, and studied the key technologies of the grinder, such as the heavy-duty belt grinding head, the controllable pitch propeller grinding CNC programming software, etc. And on these bases, we have done the four-axis simultaneous heavy belt grinding test verification on the surface of the controllable pitch propeller blade with the grinder, providing a reference to determine the reasonable marine propeller belt grinding process parameters.

빙해선박의 선수 선형에 관한 연구

The operation scenarios, types of ice, draft and propulsion system are important design point on the beginning stage of the ice breaking vessel. The concept of hull form in ice breaking vessel has to compromise the performance according to the operation route especially if ship is operating in ice and ice free water. The several hull forms were proposed to optimize the capability of the vessel in this paper. The effect of hull form according to type of ice is also discussing and explaining the ice resistance in each ice type as like pack ice, brash ice, level ice, rubble ice and ice ridge. The draft effect was examined and propulsion system for example FPP(Fixed pitch propeller), CPP(Controllable pitch propeller) and POD system was compared focusing on the propulsion efficiency.

Prediction of fretting motion in a controllable pitch propeller during service

This paper focuses on the forces acting in a controllable pitch propeller (CPP) mechanism and the manifestation of unwilling, small amplitude, vibrating motion (fretting) in a blade bearing caused by seaway. If this happens, fretting can result in fretting fatigue of components, fretting wear, and increase of friction in bearings. An attempt has been made to define the circumstances leading to fretting in a CPP and to describe the influence of sea state on fretting behaviour. Using hydrodynamic tools it is possible to determine the theoretical conditions for fretting. A combination of theoretical and experimental results provides a better understanding of the fretting phenomenon in a CPP. The first part of the paper gives an introduction to the working regimes and forces acting on a CPP. In the second part the presence of fretting is defined based on the calculation of forces and moments during one revolution of a blade in the non-actuating regime for the design condition of a specific propeller. The third part investigates self-propulsion tests in irregular seas and hydrodynamic forces acting on a CPP in those conditions. The results indicate a decrease of fretting in higher waves and higher speeds. It has been shown that it is not wise to look only at the load mean value as design criteria.

Optimization of cycloidal water turbine and the performance improvement by individual blade control

This paper investigates an advanced vertical axis turbine to enhance power generation from water energy. The turbine, known as a cycloidal water turbine, is a straight-bladed type adopting a cycloidal blade system that actively controls the rotor blades for improved turbine efficiency, according to the operating conditions. These characteristics enable the turbine to self-start and produce high electric power at a low flow speed, or under complex flow conditions. A parametric study has been carried out by CFD analysis, with various characteristics including different number of blades, chord length variations, variety of tip speed ratios, various hydrofoil shapes, and changing pitch and phase angles. Optimal parameters have been determined, and the performance of the turbine has achieved approximately 70% better performance than that of a fixed pitch turbine. An experimental study has also been carried out which shows that the results correlate quite well with the theoretical predictions although the power output was reduced due to the drag forces of the mechanical devices. Another numerical optimization was carried out to improve the rotor performance by adopting an individual blade control method. Controllable pitch angles were employed to maximize the rotor performance at various operating conditions. The optimized result obtained using genetic algorithm and parallel computing, shows an improvement in performance of around 25% compared with the cycloidal motion.

A complete design of ducted propellers using the new computer system

The computer system presented in this article is composed of several program blocks for the complete design of ship propellers. The design calculations are based on a combination of the modified lifting line theory and on the vortex lifting surface theory. The system enables solution of the following design problems: - calculation of the scale effect on the ship wake velocity field, including the influence of the propeller and rudder on this field at the propeller location - maximization of the propulsive efficiency - optimization of the propeller blade geometry on the basis of the compromise between the cavitation and blade strength requirements - optimization of the number of propeller blades and blade geometry on the basis of the acceptable level of induced pressure pulses and unsteady shaft bearing forces - calculation of the blade spindle torque for the controllable pitch propellers. The computer system is equipped with many numerical options for graphical visualization of the input data, including an easy possibility of their correction and control of the intermediate and final results of calculations.

A complete design of ship propellers using the new computer system

The computer system presented in this article is composed of several program blocks for the complete design of ship propellers. The design calculations are based on a combination of the modified lifting line theory and on the vortex lifting surface theory. The system enables solution of the following design problems: - calculation of the scale effect on the ship wake velocity field, including the influence of the propeller and rudder on this field at the propeller location - maximization of the propulsive efficiency - optimization of the propeller blade geometry on the basis of the compromise between the cavitation and blade strength requirements - optimization of the number of propeller blades and blade geometry on the basis of the acceptable level of induced pressure pulses and unsteady shaft bearing forces - calculation of the blade spindle torque for the controllable pitch propellers. The computer system is equipped with many numerical options for graphical visualization of the input data, including an easy possibility of their correction and control of the intermediate and final results of calculations.

Research on a control system based on stepping motor for ship's controllable pitch propellers

Research on a control system based on stepping motor for ship's controllable pitch propellers This paper presents description of a laboratory stand for testing servo-mechanisms of ship low-power CP propellers, as well as a remote control system for such propellers, based on electric stepping motor. Also, are presented results of the first series of tests of the control system, carried out on non-loaded CP propeller by applying stepped values of propeller pitch at two values of rotational speed of the stepping motor.

海水潤滑ゴム軸受における軸スリーブ損傷の研究―第１報

Propeller shaft diameter of ferries becomes larger in conjunction with requirements of higher vessel's speed and CPPs (controllable pitch propellers) . Thus, it may lead into a tendency to reduce the life duration of stem tube bearing under seawater lubrication. Wear of the propeller shaft sleeve, i.e. bronze alloy, is typically greater than that of the rubber bearings, with triangularly shaped craters appearing on the sleeve surface.In this paper, we describe the investigation of used sleeve sample taken from an actual vessel, as well as the wear characteristics of bronze alloys conducted under the corrosive wear condition which is equivalent to actual ferry service. The results indicated that corrosive wear was the main cause of sleeve wear. Comparing between the amount of wear in seawater and the one in distilled water, the influence of corrosion on sleeve wear was found to be substantial. Additionally, the craters are considered to be formed by the action of erosion corrosion

Aligned single-walled carbon nanotube patterns with nanoscale width, micron-scale lengthand controllable pitch

We have successfully aligned single-walled carbon nanotubes (SWNTs) inpatterns with nanoscale width, micron-scale length and controllable pitch onSiO2/Si substrates using a poly(dimethysiloxane) (PDMS) microchannel mold. Themicrochanneled mold was patterned with a funnel-shaped channel to minimizenanotube jamming during capillary-driven inflow. Two (i.e. pre- and post-capillary) gasblows were employed to improve nanotube alignment. The fluidically pre-alignedcarbon nanotubes were ‘gas-spun’ into a long 20 nm wide pattern, significantlynarrower than the fluidic pre-alignment channel. These narrow and long alignedSWNT patterns were successfully transferred to a pair of gold electrodes spaced15 µm apart. The performance of the carbon nanotube field effect transistor (CNTFET)fabricated by this technique was evaluated.