For main engine changes, shafting torsional vibration of an exported vlcc tanker. The nonlinear model of the crankshaft system with a propeller is established, in which the variable moment of inertia of the linkage and the piston, coupling effect between torsional and axial. Pdf determination of appropriate torsional vibration dampers for. Modeling method of propellers mass characteristics and damping recalculation method have been shown as an example. Even though such shafts are exposed to a wide spectrum of loads, just a few of the dominating load cases. Calculation of propulsion shafting transient torsional. Torsional vibration of a v8 aircraft engine and propeller drive system 2003011479 torsional vibration of engines has received considerable attention from researchers and engineers for many years. From the wright brothers on, many have designed, built or converted. A hydraulic zdrive consists of a highthrust, fixed pitch propeller on a husky propeller shaft directly coupled to thrustmasters exclusive podded hydraulic motor. Dimensions of propulsion shafts and their cont permissible. The ratios are changeable for fine tuning rpms and props. Torsional vibrations of the propulsion system are still among the most. Perplexing variable frequency drive vibration problems brian howes1 1beta machinery analysis ltd. Power imbalance of the engine producing a greater variance of torsion produced by the crankshaft operation of the.
In the last years, it has been noted that torsional vibration problems can be avoided by using a gfrp glass fiber reinforced plastic propeller. Research on the marine shafting torsional vibration with. The natural frequency can be calculated be considering the system as composed of two single mass systems where the shaft consist of two lengths l1 and l2 and their ends meet at. Torsional vibration measurement and analysis of improved. Introduction designer of any ship propulsion system has the main goal from the very beginning. In an aircraft with a pusher configuration as opposed to a tractor configuration, the propellers are mounted behind their respective engines. Coupling analysis of torsional vibration and engine. Research on the marine shafting torsional vibration with gears transmission xiang xu1,a, ruiping zhou1,b, mengsheng wang1,c 1college of energy and power engineering, wuhan university of technology. The shaft line consists of the crankshaft, the intermediate shaft, the propeller shaft, and. Torsional systems of marine propulsions are simulated by multiple inertias connected by linear springs and linear viscous absolute and relative damping values. Torsional vibration analysis tva provides all necessary means for steadystate vibration analyses of drive systems with focus on ship propulsion systems. Torsional vibration of a shaft with two disks when disk 1 is rotating in a counterclockwise direction, disk 2 must be rotating in a clockwise direction.
Along with the operation of shafting system, various vibration forms couple with each other and cause different kinds of coupled vibrations, which seriously threaten the safety and reliability of ships. Comprehensive studies of the complete system are required which take interactions between individual components into account. Torsional vibration of crankshaft in an enginepropeller. Over 80% of all torsional systems we analyze require system modification during the design stage to reduce the risk of failures. Pdf determination of appropriate torsional vibration. Torsional vibration problems occurred early and often in the history of aircraft engines. Optimal design for a vlcc propulsion system based on torsional. Dissectedview,cover spiflp to legend frame 2spindle 3bearing 4bearingclamp 5armature 6polepiece 7magnet 8coil 9springscrew 10cover. Torsional vibration in marine propeller drive line rob768 mechanical 9 jan 06 02. Troyfeeseisaseniorprojectengineer at engineering dynamics incorporated edi,insanantonio,texas. Another aspect is the electromechanical interaction in the airgap of the motor that produces electromagnetic torsional stiffness and damping. Consider the propeller damping as a consequence of the propellers torque characteristics. The diesel engine and propeller torsional excitation are modeled probabilistically. The propeller hub holds the blades in place and is connected to the engine through a propeller drive shaft and a gearbox.
The torsional vibration is a type of severe twisting motion in improperly designed coating machines. In recent years the torsional vibration behaviour of engine and powertrain components has gained in significance. All the components of an electric drive may affect torsional dynamics of the system. Torsional vibration in marine propeller drive line. Dnvglcg0038 calculation of shafts in marine applications. Torsional vibration is a frequent perturb for heavy rotating and high speed machinery. Vibration analysis of marine propulsion shafting by the.
The torsional vibration at the motor shaft was measured using strain gauges and the torsional vibration at the compressor auxiliary end was measured using an. Pdf transient torsional vibration analysis of iceclass propulsion. Most torsional vibration problems occurred either on the propeller or accessory end of the crankshaft. Torsional vibration an overview sciencedirect topics.
Flexible prop shaft couplings and vibration dampers. Several embodiments of torsional vibration dampers are disclosed each of which includes a first member that is detachably connected to the drive shaft and an inertial member that is coupled to the first member. Naturally the main concern is torsional excitations. Modern propellers on large turboprop airplanes typically have 4 to 6. Manley seems not to have recognized the problem as due to tor. An outboard drive having an improved arrangement for absorbing torsional vibrations and isolating the drive shaft from them. The gearbox employs hewland race car gears and is dry sump pressure oiled note the pic of the dry sump pump on the output shaft of the gearbox. Overcritical power transmission system is better for typical ship with slowspeed main engine and directly driven propeller. Any changes to these factors can result in excessive torsional vibration. The flexible couplings are designed to fit most types of marine gear flanges. The propeller consists of several blades held in place by a central hub. Shaft systems vib ration analysis is required for all ships. Us7004291b2 torsional active vibration control system. Metalblade propellers are especially critical because they have very little internal damping and closely resemble perfect springs.
Torsional vibration in main propulsion plant of a ship. Us4787868a torsional vibration damping means for marine. It was here that large inertia loads from the propeller or supercharger and their associated gear trains reacted with the natural torsional variations of the crankshaft. Power imbalance of the engine producing a greater variance of torsion produced by the crankshaft. In general simulation model of complete engine rotational speed control process, the shafting is always assumed to be rigid. Damping and excitation in the torsional vibrations. How do i consider propeller damping in torsional vibration. A typical merchantman marine propulsion system is made up of a slow speed main engine connected to a directly driven propeller by a relatively short shaft line. The electronic pdf version of this document, available free of charge. The pressure field induced by the propellers is transmitted through the surrounding water and may cause disturbance to marine life. The method includes coupling an actuator to a shaft. The report presents a torsional vibration analysis of a ships propeller shaft system driven by an electric motor. Pdf sensor placement analysis for torsional vibration.
This paper discusses several aspects of measuring and analysing torsional vibration and related. The described phenomenon concerns many aeronautical pistonengines. In order for a new propeller to be approved for a certified aircraft, it must be shown that the engine propeller airframe combination does not experience dangerous levels of stress from vibration. Paykani 3 this paper presents a design method and a vibration analysis of a carbonepoxy composite drive shaft. During operating period the following ship damages probably introduce failure risk due to torsional vibration. Torsional vibration involves the whole shaft system of the propulsion plant, embracing engine crankshaft, intermediate shafts and propeller shaft, as well as engine running gear, flywheel, propeller and where appropriate reduction gearing, flexible couplings, clutches and pto drives. Torsional vibration calculationlateral vibration calculationaxial vibration calculation. The following graphics show a typical installation space for a mediumsized stern tug application, an example of a mass elastic system of a tug drive line and the result of a modal analysis of an intermediate shaft. An american gear manufacturers association agma publication summarizes the problem as follows. Two system modelsa rigid body model and a flexible body model, are developed for predicting torsional vibrations of the crankshaft under different engine powers and propeller pitch settings. Although all classification societies require calculating. Torsional vibration involves the whole shaft system of the propulsion plant, embracing engine crankshaft, intermediate shafts and propeller shaft, as well as engine running gear, flywheel, propeller and where appropriate reduction gearing, flexible couplings, clutches. Further, a comparison has been made with similar results using a diesel direct propulsion system.
Here torsional vibrations in a main propulsion installation based on medium speed engines, gearbox and controllable pitch propeller is considered. Several norms and standards exist for inboard ship noise, vibration, and waterborne noise emission. Determination of appropriate torsional vibration dampers for. Selection and evaluation of marine shafting torsional vibrations calculation software vibration damper. The design of the composite drive shaft is divided into two main sections. Propeller damping plays an important role in torsional vibration analysis. The rubberpowered planophore, designed by alphonse penaud in 1871, was an early successful model aircraft with a pusher propeller many early aircraft especially biplanes were pushers, including the wright flyer 1903, the santosdumont 14bis 1906, the voisinfarman i 1907 and the curtiss model d used by eugene ely for the first ship landing on january 18, 1911. Dec 31, 2018 particularly complex is a vibration system consisting of an engine with an air propeller mounted on its output shaft, since the propeller blades usually have important modes of vibration which tie in with crankshaft torsional vibration. The company places high emphasis on accurate acquisition of torsional vibration data and the primary analysis. Torsional vibration of a v8 aircraft engine and propeller. The lateral vibration at the motor drive end and at the compressor drive end were measured using accelerometers oriented parallel to the piston motion horizontal direction. Abstract theoretical and experimental studies on torsional vibration of an aircraft enginepropeller system are presented in this paper.
That is accomplished by design and development engineering, and verified by an extensive vibration survey, performed in flight, using realtime data. Torsional vibration damping in a marine propulsion system. The brake is in the reduction gearbox assembly between the rear case and rear case inner diaphragm. For both elements the maximal torsional vibration stress 8. A method for damping torsional vibrations in a rotating shaft. The following observations are offered, to show some of the systems currently in use. Vibration and fatigue evaluation of airplane propellers, faa document. Torsional vibrations christian brothers university. A probabilistic approach to the torsional vibration analysis of a marine diesel engine propulsion shafting system is developed. Specialised software, for the marine power transmission system torsional vibrations analysis, made by the author, has been performed as an iterative process. The propeller is driven by a variable speed hydraulic motor. One of the earliest, the manleybalzer, apparently exhibited the effects of running at a critical speed when coupled to the shaft and bevel gear propeller drive system of langleys aerodrome 1.
Derive the damping coefficient from the propeller law. All elements are specially adapted to this specific use case for maximum usability and reliable results. Marine propulsion shafting connects the main engine and propeller, and plays an important role in promoting the movement of ships. The results of the analysis are evaluated on basis of the specifications of lloyds register of shipping. It also decreases the time needed for the propeller to come to a complete stop after engine shutdown. Torsional vibration analysis tva vibration, dynamics. For this reason, proper calculation of torsional vibrational response is needed in the initial phase of the marine shafting design 1. Electric motors and drives in torsional vibration analysis. Integration of the rudder propeller into the ships structure. Research on the marine shafting torsional vibration with gears transmission xiang xu1,a, ruiping. There is also a control system for the propeller, which will be discussed later. Mass elastic data on the engine can be provided on request from sabre engines ltd. Hessenaur, propellar drive systems and torsional vibration. Submitted in partial ful llment of the requirements for the award of doctor of philosophy of loughborough.
First, the design of the composite shaft and second, the design of its coupling. The propulsion train is composed of an electric motor, flexible coupling, spherical gears, and a propeller configuration. The torsional vibration package uses a finiteelement based formulation for performing damped and undamped torsional natural frequencies, mode shapes, stability, steadystate response, and timetransient response of mechanical drive trains. Pdf on oct 1, 2017, aaron alexander ayu and others published sensor placement analysis for torsional vibration suppression on marine electric propulsion find, read and cite all the research. Calculation of propulsion shafting transient torsional vibration. Calculation of torsional vibrations shall be performed in an early phase of designing a ship propulsion system, immediately after defining the ship propeller, selection of the main propulsion engine, eventual reduction gearbox and dimensioning of each particular. Wood and composite propellers have varying degrees of internal damping, so they tend to be more tolerant of torsional excitation. New developments in experimental analysis of torsional vibration for rotating shaft systems this item was submitted to loughborough universitys institutional repository by thean author. Torsional vibration involves the whole shaft system of the propulsion plant, embracing. Development of large torsional vibrations produce torsional stresses which leads to increase in bearing loads and results in generation of cracks in the high stress areas of the transmission system and propeller. Absolute damping is acting between a global system without rotation and the rotating inertias of engine, propeller and auxiliary drive.
Torsional vibrations in this installation may be caused by. Rotec gmbh was formed in 1988 to develop portable, pcbased equipment for use in torsional vibration testing. Torsional vibration analysis of a long propeller shaft. Ship main engine propulsion systems, vibration analysis. Jun 07, 2017 steady vibration stress in the propeller shaft and in the throw 6 aftermost cylinder marked as lumped mass 8 for open water operation condition are shown in the fig. Add or modify a pump at the free end of main engine 3. The friction corrosions appear on the surface of propeller shaft. According to british aviation author bill gunston, a pusher propeller is one mounted behind the engine, so that the drive shaft is in compression pusher configuration describes this specific propeller or ducted fan thrust device attached to.
In the nauticus torsional vibration tool, five different methods of damping calculation are available. Particularly complex is a vibration system consisting of an engine with an air propeller mounted on its output shaft, since the propeller blades usually have important modes of vibration which tie in with crankshaft torsional vibration. Vessels 12, torsional vibration of marine shafting is classified as strength problems while engine rotational speed control system as steadystate or transient droop problems. Propeller drive systems and torsional vibration written by donald p. The paper presents an estimation analysis methopd for the natural mode and frequency of the torsional vibrations of a marine power transmission system. The nature of propeller and ice block interaction requires simulating of the propulsion system dynamic response as a whole, taking into account. Dryden tuckermani propellervibrationindicator 541 legend iframe 2spindle 3bearino 4bearingclamp 5armature 6polepiece 7magnet 8coil 9springscrew figure2. Torsional vibration will vary depending on the systems characteristics and the specific operating conditions torque effort curve. An estimation method for the torsional vibration of the. This ur applies to propulsion shafts such as intermediate and propeller shafts of traditional straight forged design and which are driven by rotating machines such as diesel engines, turbines or electric motors. This torque propeller torsional amplitude induces a significant varying. New developments in experimental analysis of torsional. In this investigation of torsional vibration characteristics of the shaft systems transmitting torque, has become an important part of the designers responsibility.