Physical Modeling and Data Analysis of the Dynamic Response of a Flexibly Mounted Rotor Mechanical Seal

1995 ◽  
Vol 117 (1) ◽  
pp. 130-135 ◽  
Author(s):  
An Sung Lee ◽  
Itzhak Green
Keyword(s):  
Data Analysis ◽  
Dynamic Behavior ◽  
Theoretical Work ◽  
Experimental Investigations ◽  
Mechanical Seal ◽  
Test Rig ◽  
The Past ◽  
Recent Theoretical Work ◽  
Face Seals ◽  
Stiffness And Damping

The dynamic behavior of mechanical face seals has been an active area of research over the past three decades. Analytical and experimental investigations have exclusively been devoted to the flexibly mounted stator (FMS) seal. Recent theoretical work on the dynamics of the noncontacting flexibly mounted rotor (FMR) seal has proven that it excels in every aspect of dynamic behavior compared to the FMS seal. The advantages of the FMR seal, however, have to be experimentally verified. This work introduces a physical model (i.e., test rig) for an experimental investigation of the dynamic behavior of a noncontacting FMR seal. Features of the test rig, a new method of modeling and measuring the stiffness and damping of elastomeric O-ring secondary seals, and data analysis procedures will be introduced. Finally, experimental results will be compared with theory.

scholarly journals Excavating ghosts: Urban exploration as graffiti archaeology

2017 ◽  
Vol 15 (1) ◽  
pp. 25-45 ◽  
Author(s):  
Theo Kindynis
Keyword(s):  
Theoretical Work ◽  
Final Part ◽  
Ethnographic Research ◽  
Structured Interviews ◽  
Conceptual Metaphors ◽  
The Third ◽  
The Past ◽  
Recent Theoretical Work ◽  
Urban Exploration

Based on several years of near-nightly excursions into London’s disused, non-public, forgotten, subterranean and infrastructural spaces, this article considers the significance of discovering years - or even decades - old surviving traces of graffiti (‘ghosts’, in graffiti parlance) in situ. The article also draws on extensive ethnographic research into London’s graffiti subculture, as well as in-depth semi-structured interviews with several generations of graffiti writers. The article proceeds in four parts. The first part reflects on three sources of methodological inspiration: unauthorised urban exploration and documentation; more-or-less formal archaeological studies of graffiti; and ‘ghost ethnography’, an emergent methodological orientation which places an emphasis on absence and the interpretation of material and atmospheric traces. The second part of the article considers recent theoretical work associated with the ‘spectral turn’. Here, ghosts and haunting provide useful conceptual metaphors for thinking about lingering material and atmospheric traces of the past. The third part of the article offers some methodological caveats and reflections. The fourth and final part of the article seeks to connect theory and method, and asks what significance can be drawn from unauthorised encounters with graffiti ‘ghosts’.

Ball bearing turbocharger vibration management: application on high speed balancer

2020 ◽  
Vol 21 (6) ◽  
pp. 619
Author(s):  
Kostandin Gjika ◽  
Antoine Costeux ◽  
Gerry LaRue ◽  
John Wilson
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Ball Bearing ◽  
Squeeze Film ◽  
Design And Technology ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Bearing Loads ◽  
Stiffness And Damping

Today's modern internal combustion engines are increasingly focused on downsizing, high fuel efficiency and low emissions, which requires appropriate design and technology of turbocharger bearing systems. Automotive turbochargers operate faster and with strong engine excitation; vibration management is becoming a challenge and manufacturers are increasingly focusing on the design of low vibration and high-performance balancing technology. This paper discusses the synchronous vibration management of the ball bearing cartridge turbocharger on high-speed balancer and it is a continuation of papers [1–3]. In a first step, the synchronous rotordynamics behavior is identified. A prediction code is developed to calculate the static and dynamic performance of “ball bearing cartridge-squeeze film damper”. The dynamic behavior of balls is modeled by a spring with stiffness calculated from Tedric Harris formulas and the damping is considered null. The squeeze film damper model is derived from the Osborne Reynolds equation for incompressible and synchronous fluid loading; the stiffness and damping coefficients are calculated assuming that the bearing is infinitely short, and the oil film pressure is modeled as a cavitated π film model. The stiffness and damping coefficients are integrated on a rotordynamics code and the bearing loads are calculated by converging with the bearing eccentricity ratio. In a second step, a finite element structural dynamics model is built for the system “turbocharger housing-high speed balancer fixture” and validated by experimental frequency response functions. In the last step, the rotating dynamic bearing loads on the squeeze film damper are coupled with transfer functions and the vibration on the housings is predicted. The vibration response under single and multi-plane unbalances correlates very well with test data from turbocharger unbalance masters. The prediction model allows a thorough understanding of ball bearing turbocharger vibration on a high speed balancer, thus optimizing the dynamic behavior of the “turbocharger-high speed balancer” structural system for better rotordynamics performance identification and selection of the appropriate balancing process at the development stage of the turbocharger.

The light-scattering Mueller matrices for Rayleigh and Rayleigh-Gans-Debye approximation

1990 ◽  
Vol 55 (12) ◽  
pp. 2889-2897
Author(s):  
Jaroslav Holoubek
Keyword(s):  
Light Scattering ◽  
Theoretical Work ◽  
Matrix Elements ◽  
Elastic Light Scattering ◽  
Yield Information ◽  
Recent Theoretical Work ◽  
Particle Parameters ◽  
Complete Set ◽  
Single Matrix ◽  
Scattering Matrix Elements

Recent theoretical work has shown that the complete set of polarized elastic light-scattering studies should yield information about scatterer structure that has so far hardly been utilized. We present here calculations of angular dependences of light-scattering matrix elements for spheres near the Rayleigh and Rayleigh-Gans-Debye limits. The significance of single matrix elements is documented on examples that show how different matrix elements respond to changes in particle parameters. It appears that in the small-particle limit (Rg/λ < 0.1) we do not loose much information by ignoring "large particle" observables.

scholarly journals Magnetospheric Structure of Rotation-Powered Neutron Stars

1992 ◽  
Vol 128 ◽  
pp. 56-77 ◽  
Author(s):  
Jonathan Arons
Keyword(s):  
Radio Emission ◽  
Gamma Radiation ◽  
Heavy Ions ◽  
Theoretical Work ◽  
Future Research ◽  
Observational Constraints ◽  
Polar Caps ◽  
Recent Theoretical Work ◽  
Density Flow ◽  
Promising Avenue

AbstractI survey recent theoretical work on the structure of the magnetospheres of rotation-powered pulsars, within the observational constraints set by their observed spindown, their ability to power synchrotron nebulae and their ability to produce beamed collective radio emission, while putting only a small fraction of their energy into incoherent X- and gamma radiation. I find no single theory has yet given a consistent description of the magnetosphere, but I conclude that models based on a dense outflow of pairs from the polar caps, permeated by a lower density flow of heavy ions, are the most promising avenue for future research.

Influence of a Honeycomb Facing on the Flow Through a Stepped Labyrinth Seal

2000 ◽  
Vol 124 (1) ◽  
pp. 140-146 ◽  
Author(s):  
V. Schramm ◽  
K. Willenborg ◽  
S. Kim ◽  
S. Wittig
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Theoretical Work ◽  
Labyrinth Seal ◽  
Honeycomb Structure ◽  
Experimental Investigations ◽  
Labyrinth Seals ◽  
Numerical Predictions ◽  
Flow Through ◽  
Aero Engines

This paper reports numerical predictions and measurements of the flow field in a stepped labyrinth seal. The theoretical work and the experimental investigations were successfully combined to gain a comprehensive understanding of the flow patterns existing in such elements. In order to identify the influence of the honeycomb structure, a smooth stator as well as a seal configuration with a honeycomb facing mounted on the stator wall were investigated. The seal geometry is representative of typical three-step labyrinth seals of modern aero engines. The flow field was predicted using a commercial finite volume code with the standard k-ε turbulence model. The computational grid includes the basic seal geometry as well as the three-dimensional honeycomb structures.

Leakage Flow Investigations on a Through-Wall Crack Related to Thermal Fatigue of Nuclear Power Plant Piping

2017 ◽  
Author(s):  
Stefan Schmid ◽  
Rudi Kulenovic ◽  
Eckart Laurien
Keyword(s):  
Experimental Data ◽  
Nuclear Power ◽  
Numerical Models ◽  
Measurement Techniques ◽  
Experimental Investigations ◽  
Leakage Flow ◽  
Test Rig ◽  
Reduced Pressure ◽  
Flow Rates ◽  
Set Up

For the validation of empirical models to calculate leakage flow rates in through-wall cracks of piping, reliable experimental data are essential. In this context, the Leakage Flow (LF) test rig was built up at the IKE for measurements of leakage flow rates with reduced pressure (maximum 1 MPA) and temperature (maximum 170 °C) compared to real plant conditions. The design of the test rig enables experimental investigations of through-wall cracks with different geometries and orientations by means of circular blank sheets with integrated cracks which are installed in the tubular test section of the test rig. In the paper, the experimental LF set-up and used measurement techniques are explained in detail. Furthermore, first leakage flow measurement results for one through-wall crack geometry and different imposed fluid pressures at ambient temperature conditions are presented and discussed. As an additional aspect the experimental data are used for the determination of the flow resistance of the investigated leak channel. Finally, the experimental results are compared with numerical results of WinLeck calculations to prove specifically in WinLeck implemented numerical models.

ANALISIS LOYALITAS PELANGGAN HOTEL SYARIAH DI DAERAH ISTIMEWA YOGYAKARTA

2019 ◽  
Vol 13 (03) ◽  
pp. 15-30
Author(s):  
Dwi Agus Kristianto ◽  
Amin Kiswantoro
Keyword(s):  
Data Analysis ◽  
Linear Regression ◽  
Data Collection ◽  
Service Quality ◽  
Customer Loyalty ◽  
Brand Image ◽  
Tourist Destinations ◽  
The Past ◽  
The World ◽  
Special Region

In the past the function of the hotel was only as a place to stay for consumers who travel on business or tourism and do not have a relationship or family at their destination. Sharia concept hotels continue to grow along with the needs of Muslim consumers around the world. The concept of sharia hotels also continues to grow in Indonesia, especially in the Yogyakarta region as one of the tourist destinations in Indonesia. This study aims to determine the effect of price, service quality and brand image on customer loyalty of sharia hotels in Yogyakarta Special Region both partially and simultaneously.This type of research is causally comparative. The variables in this study are price, service quality, brand image and customer loyalty. The population in this study are customers who have visited sharia hotels in Yogyakarta. Sampling was done by nonrandom sampling, specifically using purposive sampling where the sample was taken from the population, with the following criteria: 1) Customers who had stayed in sharia hotels in Yogyakarta more than twice, and 2) Respondents aged 18 years. The sample in this study was taken as many as 100 respondents. Data collection techniques using questionnaires. Data analysis used is multiple linear regression analysis.Based on the results of the study, the following conclusions are obtained: (1) Prices have a positive and significant effect on customer loyalty; (2) Service quality has a positive and significant effect on customer loyalty; (3) Brand image has a positive and significant effect on customer loyalty; and (4) Price, service quality, and brand image have a positive and significant effect on customer loyalty. Keywords: hotel, sharia, price, service quality, brand image, customer loyalty.

Investigation of Scale Effects in Sailing Yacht Performance Prediction by Experimental Methods

2013 ◽  
Author(s):  
Mustafa Insel ◽  
Ziya Saydam
Keyword(s):  
Performance Prediction ◽  
Research Study ◽  
Scale Effects ◽  
Waiting Times ◽  
Wave Pattern ◽  
Experimental Investigations ◽  
The Past ◽  
Scale Models ◽  
Sailing Yacht ◽  
Testing Techniques

A substantial amount of research has been carried out in the past to enhance the testing techniques and to increase the accuracy associated with tank testing of sailing yachts. The majority of this work was associated with high budgeted campaigns; large models, long waiting times and high budgets became standard practice in the field. This led to lack of accessibility for low budgeted campaigns and for designers of ordinary sailing yachts to these tests. A research study has been initiated to investigate the scale effects associated with tank testing of sailing yachts. The intention has been to make best use of modern experimental and computational methods to understand the scale effects in conjunction with systematic tank tests. Both viscous and wave components were considered for investigation of scale effects in sailing yacht performance prediction. Four different scale models ranging from 1/4 to 1/10 of a TP52 yacht have been tested in the towing tank in upright and heeled condition while full, half and quarter scale computational analysis have been carried out with a RANS code. The wave pattern measurements were conducted for all upright and heeled cases with the use of three wave probes on each side. Variation of drag, side force, running attitude and wave pattern have been investigated. This paper focuses on the experimental investigations both in the upright and heeled conditions.

scholarly journals The uncertainty in stiffness and damping of an automotive vehicle’s trim-structure mounts and its effect on the variability of the vibration transfer function

2017 ◽  
Vol 232 (15) ◽  
pp. 2587-2598 ◽  
Author(s):  
Ali Abolfathi ◽  
Dan J O’Boy ◽  
Stephen J Walsh ◽  
Amy M Dowsett ◽  
Stephen A Fisher
Keyword(s):  
Boundary Condition ◽  
Transfer Function ◽  
Dynamic Response ◽  
Transfer Functions ◽  
Effective Stiffness ◽  
3D Printer ◽  
Structural Elements ◽  
Test Rig ◽  
Manufacturing Tolerances ◽  
Stiffness And Damping

A large number of plastic clips are used in an automotive vehicle to connect the trim to the structure. These are small clips with very small masses compared to the structural elements that they connect together; however, the uncertainty in their properties can affect the dynamic response. The uncertainty arises out of their material and manufacturing tolerances and more importantly the boundary conditions. A test rig has been developed that can model the mounting condition of the clips. This allows measurement of the range of their effective stiffness and damping. Initially, the boundary condition at the structure side is replicated. The variability is found to be 7% for stiffness and 8% for damping. In order to simulate the connection of the trim side, a mount is built using a 3D printer. The variability due to the boundary condition on both sides was as large as 40% for stiffness and 36% for damping. A Monte Carlo simulation is used in order to assess the effect of the uncertainty of the clips’ properties on the vibration transfer functions of a door assembly. A simplified connection model is used in this study where only the axial degree of freedom is considered in connecting the trim to the door structure. The uncertainty in the clip stiffness and damping results in a variability in the vibration transfer function which is frequency dependent and can be as high as 10% at the resonant peaks with higher values at some other frequencies. It is shown that the effect of the uncertainty in the clips effective damping is negligible and the variability in the dynamic response is mainly due to the uncertainty in the clip’s stiffness. Furthermore, it is shown that the variability would reduce either by increasing or decreasing the effective stiffness of the clips.

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