Forty-Eight Ordinate Harmonic Analysis and the Harmonic Spectrum of Two-Cycle Diesel Torque

1940 ◽  
Vol 7 (4) ◽  
pp. A158-A160
Author(s):  
Nancy Klock
Keyword(s):  
Diesel Engine ◽  
Numerical Methods ◽  
Harmonic Analysis ◽  
Numerical Method ◽  
Gasoline Engine ◽  
Harmonic Spectrum ◽  
Torsional Vibrations ◽  
Harmonic Content ◽  
Good Account ◽  
Torque Curve

Abstract For the harmonic analysis of periodic curves, machines as well as numerical methods are available. The machines are expensive and not generally available, and time is required to learn their operation. Therefore, an occasional analysis of a curve consumes even less time by the numerical method than by the machine. The best known numerical method is that of Runge (1) described in many places; a good account is found in Scarborough’s book (2). The principle is clear, but writers usually give the method for 6, 12, or 24 ordinates for the sake of simplicity, which is not sufficiently accurate for most applications. In this paper the 48-ordinate scheme is fully given in Tables 1, 2, and 3. For the analysis of torsional vibrations the harmonic content of the torque curve of the disturbing engine is required. Such analyses have been published for the four-cycle Diesel engine (3) and for the four-cycle gasoline engine for aviation purposes (4). But to the author’s knowledge none have been published for the two-cycle Diesel engine. Such a spectrum is given herein.

Vortex Simulation of Rotor/Stator Interaction in Turbomachinery

1998 ◽  
Author(s):  
Xian Hong Wu ◽  
Mao Zhang Chen
Keyword(s):  
Numerical Methods ◽  
Flow Field ◽  
Diffusion Process ◽  
Numerical Method ◽  
Outer Region ◽  
Vortex Method ◽  
Convective Process ◽  
Rotor Stator Interaction ◽  
Initial Description ◽  
Lagrangian Frame

A new numerical method is presented in this paper to simulate rotor/stator interaction in turbomachinery by use of a vortex method based on a Lagrangian frame. The algorithm takes the result from steady solution as input, which can give an initial description of the unsteady disturbance flow field. To calculate the unsteady response to these disturbances, the Lagrangian vortex method is used to capture the convective process, and the deterministic vortex scheme to approximate the viscous diffusion process. The application of Baldwin-Lomax turbulence model in wakes is developed, so as to overcome the difficulties such as the much higher calculated viscosity in the outer region than that in the boundary regions, and the difficulty in continuously tracing moving wake centerlines encounted by other numerical methods. The agreement between the computational and experimental results is generally good. The sweeping characteristic of wakes, the influence of unsteadiness on incidence and the decaying features of unsteady velocities, pressure are included in the paper.

Transient and Unstable Torsional Vibrations on a 4-Stroke Marine Diesel Engine

2003 ◽  
Author(s):  
D. C. Lee ◽  
J. D. Yu
Keyword(s):  
Diesel Engine ◽  
Torsional Vibration ◽  
Marine Diesel Engine ◽  
Torsional Vibrations ◽  
Steady State Condition ◽  
Marine Propulsion ◽  
Friction Clutch ◽  
Marine Diesel ◽  
Noise Measurements ◽  
Unstable Vibration

Under steady state condition, unstable torsional vibration normally does not occur in shafting systems using 4stroke diesel engine due to hysteresis damping of shafting system and relative damping of standard fitted damper. However, the unstable torsional vibration occurs on marine propulsion shafting systems due to slippage of a multi-friction clutch installed between increasing gear box and shaft generator. To identify this unstable vibration and make proper counter measure, the simulation for transient torsional vibration using the Newmark method is introduced in this paper. The mechanism of this unstable vibration is verified by vibration and noise measurements of the shafting system.

scholarly journals PEMAHAMAN METODE NUMERIK MENGGUNAKAN PEMPROGRMAN MATLAB (Studi Kasus : Metode Secant)

2017 ◽  
Vol 1 (1) ◽  
pp. 89
Author(s):  
Melda Panjaitan
Keyword(s):  
Approximate Solution ◽  
Problem Solving ◽  
Numerical Methods ◽  
Numerical Method ◽  
Mathematical Problem ◽  
Secant Method ◽  
Mathematical Problem Solving ◽  
Real Solution ◽  
True Solution ◽  
Solution Approach

Abstract - The numerical method is a powerful mathematical problem solving tool. With numerical methods, we get a solution that approaches or approaches a true solution so that a numerical solution is also called an approximate solution or solution approach, but almost the solution can be made as accurately as we want. The solution almost certainly isn't exactly the same as the real solution, so there is a difference between the two. This difference is called an error. the solution using numerical methods is always in the form of numbers. The secant method requires two initial estimates that must enclose the roots of the equation. Keywords - Numerical Method, Secant Method

scholarly journals Semi-Precise Analytical Method for Investigating the Liftoff Variation on the Hall Sensor in Metal Defect Sensing

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5539
Author(s):  
Ali Azad ◽  
Jong-Jae Lee ◽  
Namgyu Kim
Keyword(s):  
Numerical Methods ◽  
Hall Effect ◽  
Numerical Method ◽  
Surface Defects ◽  
Simulation Method ◽  
Hall Sensor ◽  
Induced Current ◽  
Element Analysis ◽  
Hall Effect Sensor ◽  
Conventional Numerical Method

Hall-effect sensors are used to detect metal surface defects both experimentally and numerically. The gap between the specimen and the sensor, called the liftoff, is assumed to remain constant, while a slight misplacement of a sample may lead to incorrect measurements by the Hall-effect sensor. This paper proposes a numerical simulation method to mitigate the liftoff issue. Owing to the complexity of conducting precise finite-element analysis, rather than obtaining the induced current in the Hall sensor, only the magnetic flux leakage is obtained. Thus, to achieve a better approximation, a numerical method capable of obtaining the induced current density in the circumferential direction in terms of the inspection direction is also proposed. Signals of the conventional and proposed approximate numerical methods affected by the sensor liftoff variation were obtained and compared. For small liftoffs, both conventional and proposed numerical methods could identify notch defects, while as the liftoff increased, no defect could be identified using the conventional numerical method. Furthermore, experiments were performed using a variety of liftoff configurations. Based on the results, considering the threshold of the conventional numerical method, defects were detected for greater liftoffs, but misdetection did not occur.

scholarly journals Numerical simulation of minor losses coefficient on the example of elbows

2018 ◽  
Vol 180 ◽  
pp. 02093
Author(s):  
Smyk Emil ◽  
Mrozik Dariusz ◽  
Olszewski Łukasz ◽  
Peszyński Kazimierz
Keyword(s):  
Numerical Simulation ◽  
Numerical Methods ◽  
Numerical Method ◽  
Cross Section ◽  
Analytical Methods ◽  
Circular Cross Section ◽  
Experimental Methods ◽  
Loss Coefficient ◽  
Complicated Problem ◽  
Minor Losses

Determining of minor losses coefficient is very complicated problem. Analytical methods are often very difficult and experimental methods are very expensive and time-consuming. Consequently, the use of numerical methods seems to be a good solution, but there are no publications describing this issue. Therefore, the paper is describing the numerical method of determining the minor loss coefficient ξ on the example of elbows with circular cross-section.

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