Experimental Study on the Influence of Water and Cavitation on Propeller Load during Ice-Propeller Milling

When the ice-class propeller sails in an icy sea, it is affected by external factors such as water, ice, and cavitation, and the process of mutual interference is extremely complicated. In order to study the influence of water and cavitation on propeller load during the ice-propeller milling process, a test platform for ice–water propeller milling action was constructed. The load and cavitation of the propeller and single blade were measured during ice-propeller milling in air and water (atmospheric pressure and decompression conditions). Simultaneously, the changes in the load and bearing force of the propeller and blade were studied at different working conditions. The results show that, in the process of ice–water propeller milling, the direction of the propeller thrust generated by the water is opposite to that of the axial force generated by ice; the combined action of the two causes propeller thrust loss, whereas the combined action of water and ice increases propeller torque. The presence of water increases the thrust, torque, and bearing force of the fluctuating amplitude of the blade. The occurrence of cavitation reduces the thrust and torque of the propeller and blade and increases thrust fluctuating amplitudes while decreasing the tangential force fluctuating amplitude of the blade.

Comprehensive Design Method for Open or Ducted Propellers for Underwater Vehicles

A comprehensive method which determines the most efficient propeller blade shapes for a given axisymmetric hull to travel at a desired speed, is presented. A nonlinear optimization method is used to design the blade, the shape of which is defined by a 3-D B-spline polygon, with the coordinates of the B-spline control points being the parameters to be optimized for maximum propeller efficiency, for given effective wake and propeller thrust. The performance of the propeller within the optimization scheme is assessed by a vortex-lattice method (VLM). To account fully for the hull/propeller interaction, the effective wake to the propeller and the hull resistance are determined by analyzing the designed propeller geometry by the VLM, coupled with a Reynolds-Averaged Navier-Stokes (RANS) solver. The optimization method re-designs the optimum blade with the updated effective wake and propeller thrust (taken to be equal to the updated hull resistance), and the procedure continues until convergence of the propeller performance. The current approach does not require knowledge of the wake fraction or the thrust deduction factor, both of which must be estimated a priori in traditional propeller design. The method is applied for a given hull to travel at a desired speed, and the optimum blades are designed for various combinations of propeller diameter and RPM, in the case of open and ducted propellers with provided duct shapes. The effects of the propeller diameter and RPM on the designed propeller thrust, torque, propeller efficiency, and required power are presented and compared with each other in the case of open and ducted propellers. The present approach is shown to provide guidance on the design of propulsors for underwater vehicles, and is applicable to the design of propulsors for surface ships.

Full-Scale Measurements of the Propeller Thrust during Speed Trials Using Electrical and Optical Sensors

Full-scale sea trials demonstrate a ship’s performance under real operating conditions to confirm whether a ship meets its specifications and requirements. The determination of the performance through a sea trial is the most important stage in the ship design cycle. If one is relying on measurements of propeller shaft power or fuel consumption, the distinction between the propeller and hull efficiencies may not be made. In order to be able to identify the propeller efficiency separate from the hull, full-scale propeller thrust should be accurately measured. In this study, full-scale measurements of the propeller thrust, torque, and revolution for a series of crude oil tankers and twin-skeg LNG carrier were conducted during the speed trials. Two different measuring systems, strain gauge and optical type, were implemented to compare the performance of sensors. As a result, it was shown that the strain gauge type-measuring device matched the model test results relatively well compared to the optical device. Above all, in the case of the optical device, it has been demonstrated that the zero setting is important to increase the accuracy of the full-scale measurements.

Simulasi Graphical User Interface Analisis Termodinamika Mesin Turboprop Menggunakan Perangkat Lunak Matlab R2020a

A turboprop engine is a hybrid engine that delivers thrust or jet thrust and also drives the propeller. This is basically similar to a turbojet except the turbine works through the main shaft which is connected to the reduction gear to rotate the propeller in front of the engine. This research was conducted to determine the development of engine performance in thermodynamic analysis so as to know the value of each parameter on a engine that has been developing for 20 to 50 years with different engine manufacturing. So that in this study a comparison of the thermodynamic analysis of the TPE-331, PT6A-42 and H85-200 engines was carried out. In the TPE331-10, PT6A-42, and H85-200 turboprop engines the value of fuel to air ratio and shaft work increases with increasing altitude while compressor work, fuel flow rate, shaft power, propeller thrust, jet thrust, total thrust, equivalent engine power and ESFC decrease with increasing altitude. Furthermore, the turbine's working value is relatively stable as the altitude increases. After that, the value of compressor work and turbine work on the PT6A-42 engine was greater than that of the TPE331-10, and H85-200 engines. However, the value of the fuel to air ratio, fuel flow rate, shaft power, jet thrust, equivalent engine power and ESFC on the H85-200 engine was greater than the TPE331-10 and PT6A engines. Furthermore, at sea level, the value of the axle, propeller thrust, and total thrust on the H85-200 engine is greater than that of the TPE331-10 and PT6A-42 engines but at an altitude of 25,000 ft, the PT6A-4 engine has a greater value than that of the TPE331-10 and PT6A-42 engines. TPE331-10, and H85-200 engines.

ANALISA ENGINE PROPELLER MATCHING (EPM) PADA KAPAL RESCUE BOAT KARENA PERUBAHAN TAHAP POWERING PROCESS

This study is to investigate compatibility between installed main engine in ship with propeller design using theoretical approach and data series. A triple screw rescue boat conducted hard chain hull was used for study and analyze the effect of the changes in powering process stage by observing the result of open water efficiency based on Wageningen Data Series with cavitation analysis has been neglected. The study is considered using intersection between propeller thrust with thrust coefficient and open water efficiency on Wageningen B-Series for fixed pitch propeller. The result indicated that propeller characteristic B5-76 with 41% of efficiency has compatibility with specification of installed main engine.

Determining the acceptable turning circle manoeuvring modes to avoid loss of efficiency of the twin propeller system

Nowadays, a large number of newly built inland and navy vessels are equipped with a twin propeller-twin rudder configuration (TPTR). Observations of the modes of work of each unit of the TPTR system when performing manoeuvres at curvilinear trajectory show asymmetrical loading. The nature and parameters of the phenomenon are not sufficiently studied, which in specific manoeuvres could create overloading and loss of effectiveness. The purpose of the task is to study the effectiveness of the ship’s TP system in manoeuvring, taking into account the specifics of working in oblique flow of the “internal” and “external” propellers, respectively to the trajectory of motion. Appropriate manoeuvring experiments with self-running ship model have been carried out by which the propeller thrust and torque have been measured. In the present paper, based on obtained investigation results, analysis of interaction effects in the TP system has been performed. Coefficients for estimating the asymmetric efficiency of the twin-screw system have been developed, and related conclusions were summarized.