Extensions of Campbell’s Major Resonance With an Experimental Demonstration for a Counter-Rotating Turbine

2011 ◽  
Author(s):  
Robert P. Czachor
Keyword(s):  
Propagation Speed ◽  
Harmonic Excitation ◽  
Test Results ◽  
Experimental Demonstration ◽  
Resonance Mechanism ◽  
Nodal Diameter ◽  
Adjacent Structure ◽  
Component Test ◽  
Adjacent Structures ◽  
Wave Propagation Speed

The interaction of vibratory traveling waves in rotating components with adjacent structures is examined. In the most general case, a resonance can occur when the wave propagation speed for a nodal diameter n mode in rotor 1 is equal in speed and direction to the rotational speed of an adjacent structure ω2. When ω2 = 0 this structure is a stator and the phenomenon is a major resonance, as discussed in Wilfred Campbell’s paper [1] of 1924. An identical phenomena can occur when ω2 ≠ 0 between rotor 1 and a co- or counter-rotating rotor 2 if a suitable harmonic excitation is generated. Description of component test results which demonstrated this resonance mechanism is provided.

Extension of Campbell's Major Resonance With Experimental Demonstration

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Robert P. Czachor
Keyword(s):  
Wave Propagation ◽  
Rotational Velocity ◽  
Propagation Speed ◽  
Experimental Demonstration ◽  
Adjacent Structure ◽  
Component Test ◽  
Turbine Disc ◽  
Wave Propagation Speed ◽  
Trans Asme ◽  
Classic Paper

The interaction of vibratory traveling waves in rotating and stationary axisymmetric components is examined. In the most general case, a resonance can occur when the wave propagation speed in a first structure is equal in magnitude and direction to the rotational velocity of an adjacent structure. When a backward wave in a rotor appears stationary, a major resonance, as discussed in Wilfred Campbell's classic paper (Campbell, W., 1924, “The Protection of Steam Turbine Disc Wheels from Axial Vibrations,” Trans ASME, 46, pp. 31–160), results. A related resonance has been observed when the wave propagation speed in the stator is equal to the physical speed of the adjacent rotor. A third mechanism is derived for resonance between a wave in rotor 1 and a co- or counter-rotating rotor 2. Description of a component test which demonstrated this final phenomenon is provided.

scholarly journals The Analysis of Melde Tool as Learning Media on Students Senior High School

2020 ◽  
Vol 9 (4) ◽  
Author(s):  
Zul Jalal Hadi ◽  
Nazar Amrullah ◽  
Aruna Akbar Zhafransyah
Keyword(s):  
High School ◽  
Wave Propagation ◽  
Propagation Speed ◽  
Stationary Wave ◽  
Senior High School ◽  
Learning Tools ◽  
Test Results ◽  
Physics Concepts ◽  
Wave Propagation Speed ◽  
Load Mass

Physics is one of the subjects in high school taught by educators. However, in learning physical concepts are not only theoretically studied but in experiments or practicum. However, not all learning of physics concepts uses practice or experiment. This happens due to lack of facilities, time, and the low ability of teachers in making tools. Therefore the writer makes physics practice tools as learning tools and media namely Melde. The purpose of this discussion is as a medium of learning stationary wave material. The test results of making a melde tool on a stationary wave material are that the wave propagation speed on a rope depends on the length and weight of the load, the load mass relationship and the wave propagation speed are proportionally sincere, and the greater the load the greater the faster the propagation. Based on the results of testing the making of medle tool on stationary wave material it is suitable for use as a learning medium in schools.

Influence of the applied pressure of the transducer on the propagation speed of the ultrasonic wave in wood

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Edgar V.M. Carrasco ◽  
Rejane C. Alves ◽  
Mônica A. Smits ◽  
Vinnicius D. Pizzol ◽  
Ana Lucia C. Oliveira ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Applied Pressure ◽  
Pressure Gauge ◽  
Eucalyptus Grandis ◽  
Propagation Speed ◽  
Ultrasonic Waves ◽  
Ultrasonic Speed ◽  
Wave Propagation Speed ◽  
Propagation Technique ◽  
Non Destructive

Abstract The non-destructive wave propagation technique is used to estimate the wood’s modulus of elasticity. The propagation speed of ultrasonic waves is influenced by some factors, among them: the type of transducer used in the test, the form of coupling and the sensitivity of the transducers. The objective of the study was to evaluate the influence of the contact pressure of the transducers on the ultrasonic speed. Ninety-eight tests were carried out on specimens of the species Eucalyptus grandis, with dimensions of 120 × 120 × 50 mm. The calibration of the pressure exerted by the transducer was controlled by a pressure gauge using a previously calibrated load cell. The robust statistical analysis allowed to validate the experimental results and to obtain consistent conclusions. The results showed that the wave propagation speed is not influenced by the pressure exerted by the transducer.

scholarly journals К теории рассеяния Мандельштама-Бриллюэна в плазменном слое

2020 ◽  
Vol 128 (1) ◽  
pp. 98
Author(s):  
С.А. Двинин ◽  
Д.К. Солихов ◽  
Ш.С. Нурулхаков
Keyword(s):  
Wave Propagation ◽  
Pump Wave ◽  
Plasma Layer ◽  
Brillouin Scattering ◽  
Propagation Speed ◽  
Local Source ◽  
Arbitrary Angle ◽  
Perturbation Amplitude ◽  
Wave Propagation Speed ◽  
Over Time

The evolution of a perturbation from a local source for Mandel'shtam-Brillouin scattering in a plasma layer with unlimited length is calculated. Perturbation over time in this case can either leave the scattering region through one of the two boundaries, or propagate along the layer at a speed below sound wave propagation speed, with an exponential growth, or a fall in perturbation amplitude. In the particular case of strictly backward scattering (the scattering angle is π), this propagation velocity is zero. The paper calculates the threshold instability fields and the instability increments, taking into account both convective losses and collisional attenuation of waves. It is shown that the instability threshold for scattering at an arbitrary angle can be lower than for strictly backwards scattering and when the threshold is exceeded by the intensity of the pump wave; the scattering increment at an angle can also be higher than the increment for backscattering. When the threshold is greatly exceeded, the convective losses can be neglected, and the largest increment is observed for backward scattering.

scholarly journals Impact Response of Base Isolated Building with Adjacent Structures

10.29007/275r ◽  
2018 ◽  
Author(s):  
Niraj Shinde ◽  
Devesh Soni
Keyword(s):  
Impact Response ◽  
Gap Effect ◽  
Viscous Damper ◽  
Base Shear ◽  
Pendulum System ◽  
Adjacent Structure ◽  
Adjacent Structures ◽  
Impact Element ◽  
The Impact ◽  
Floor Acceleration

The seismic behavior of multi-storied building supported on Friction pendulum system (FPS) during impact with adjacent structure is examined. One lateral degree of freedom is considered at each floor, base mass and slider. Adjacent structure (i.e. retaining walls or entry bridges) is modeled as an impact element in form of spring and dashpot. The impact response of FPS bearing is studied under 60 records consisting of service level, design basis and maximum credible earthquakes. Newmark’s step by step iteration method is used to solve the differential equations of motion for the isolated system. The impact response of isolated building is studied under the variation of important system parameters such as size of gap and stiffness of impact element. To reduce the influence of impact a viscous damper is employed between the isolated building and adjacent structure. It is concluded that during impact with adjacent structure the superstructure acceleration and base shear increases while bearing displacement decreases. The employment of viscous damper shows considerable reduction in bearing displacements, base shear and impact force during DBE and MCE events. Further, the effects of impact are found critical if the superstructure is flexible and greater stiffness of impact element. The top floor acceleration increases with the isolation gap up to certain limit and again reduces with the increase in isolation gap.Keywords - Adjacent Structure; isolation; Sliding bearing; Viscous Damper; Gap effect; Floor acceleration; Impact

Analytical and Optimization Study of Propagation and Reduction of Wave in Granular Sand by DEM Method

2021 ◽  
Author(s):  
Amin Moslemi Petrudi ◽  
Masoud Rahmani
Keyword(s):  
Wave Propagation ◽  
Particle Density ◽  
Propagation Speed ◽  
Granular Soils ◽  
Discrete Elements ◽  
Factors Affecting ◽  
Interparticle Force ◽  
Optimization Study ◽  
Solution Methods ◽  
Wave Propagation Speed

In this research, the discrete element method has been used to analyze wave propagation and to investigate the factors affecting wave reduction in granular soils. The method of discrete elements is important because of the possibility of preparing completely similar specimens and examining the effect of changes in a certain parameter on the Behavior of the specimens. This method also provides an understanding of the changes that have occurred at the micro-scale of granular materials that are not achievable with other laboratory and numerical methods. To model the specimens, a set of disks with specific granulation has been used for two-dimensional studies. PFC 2D software has been used to perform simulations and related analyzes such as interparticle force. The DEM code in MATLAB is used to check the wave depreciation. In this research, the optimization process was performed using experimental data and the Taguchi method using the DEM method. The results of this study show that there is a direct relationship between the number of particle set contacts and the wave propagation speed. Also, material properties such as particle density are the most important parameters affecting wave velocity. The results of the method (DEM) are done with PFC 2D software and a comparison between the results of this method with the solution methods used by other researchers is shown to be a good match.

scholarly journals Prediction of fatigue limit of journal bearings considering a multi-axial stress state

2016 ◽  
Vol 68 (3) ◽  
pp. 430-438 ◽  
Author(s):  
Christopher Sous ◽  
Henrik Wünsch ◽  
Georg Jacobs ◽  
Christoph Broeckmann
Keyword(s):  
Stress State ◽  
Axial Stress ◽  
Design Guidelines ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Test Results ◽  
Content Type ◽  
Operation Conditions ◽  
Component Test ◽  
Material Tests

Purpose The purpose of this paper is to investigate the applicability of the quadratic failure hypothesis (QFH) on journal bearings coated with a white metal sliding layer on the prediction of safe and unsafe operating conditions. The hypothesis covers operation conditions under static and dynamical loading. Design/methodology/approach Material tests and elastohydrodynamic, as well as structural, simulations were conducted to provide the required input data for the failure hypothesis. Component samples were tested to verify the results of the QFH. Findings The load bearing capacity of journal bearings was analysed for different operating conditions by the use of the QFH. Results allow for the identification of critical and non-critical loading conditions and are in accordance with component test results. Originality/value Today’s design guidelines for journal bearings do not consider a multi-axial stress state and actual stress distribution. The applied hypothesis enables consideration of multiaxiality inside the sliding surface layer, as well as determining the location of bearing fatigue due to material overload.

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