scholarly journals Experimental Analysis of Dynamic Interaction Between a Centrifugal Compressor and Its Casing

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
P. Almeida ◽  
C. Gibert ◽  
F. Thouverez ◽  
X. Leblanc ◽  
J.-P. Ousty
Keyword(s):  
Centrifugal Compressor ◽  
Time Series Data ◽  
Laser Doppler Vibrometer ◽  
Series Data ◽  
Physical Parameters ◽  
Full Spectrum ◽  
Rotating Speed ◽  
Scanning Laser Doppler Vibrometer ◽  
System Nonlinearity ◽  
Run Up

In turbomachinery, one way to improve aerodynamic performance and reduce fuel consumption consists of minimizing the clearance between rotor and casing. Yet, the probability of contact is increased and this may lead in some specific conditions to a large and even unstable excitation on the impeller and stator. To achieve better understanding of the dynamic behavior occurring during the blade-to-casing contact, many numerical studies have been conducted but only a few experiments have been reported in the literature thus far. The interaction experiment reported in this paper involves a low-pressure, rotating centrifugal compressor and its casing tested in a vacuum chamber. Contact is initiated by introducing a gap near zero, and certain events with significant dynamic levels are observed during the run-up. Measurements are performed using strain gauges on both the rotating and stationary parts and a scanning laser Doppler vibrometer on the stator. This research focuses on an analysis of the recorded data. Time series data are also analyzed by means of standard signal processing and a full spectrum analysis in order to identify the direction of traveling wave propagation on the two structures as well as nodal diameters and frequencies. The dynamic response of structures is accompanied by variations in other physical parameters such as temperature, static deformed shapes, speed, and torque. A wearing pattern is evaluated following the contact experiments. The spectral content of response is dominated by frequency modes excited by rotating speed harmonics as well as by sidebands due to inherent system nonlinearity.

scholarly journals Experimental Analysis of Dynamic Interaction Between a Centrifugal Compressor and its Casing

2014 ◽  
Author(s):  
P. Almeida ◽  
C. Gibert ◽  
F. Thouverez ◽  
X. Leblanc ◽  
J.-P. Ousty
Keyword(s):  
Centrifugal Compressor ◽  
Time Series Data ◽  
Laser Doppler Vibrometer ◽  
Series Data ◽  
Physical Parameters ◽  
Full Spectrum ◽  
Scanning Laser Doppler Vibrometer ◽  
Recorded Data ◽  
Interaction Experiment ◽  
Run Up

In turbomachinery, one way to improve aerodynamic performance and reduce fuel consumption consists of minimizing the clearance between rotor and casing. Yet the probability of contact is increased and this may lead in some specific conditions to a large and even unstable excitation on the impeller and stator. To achieve better understanding of the dynamic behavior occurring during the blade-to-casing contact, many numerical studies have been conducted but only a few experiments have been reported in the literature thus far. The interaction experiment reported in this paper involves a low-pressure, rotating centrifugal compressor and its casing tested in a vacuum chamber. Contact is initiated by introducing a gap near zero, and certain events with significant dynamic levels are observed during the run-up. Measurements are performed using strain gauges on both the rotating and stationary parts and a Scanning Laser Doppler Vibrometer on the stator. This research focuses on an analysis of the recorded data. Time series data are also analyzed by means of standard signal processing and a full spectrum analysis in order to identify the direction of traveling wave propagation on the two structures as well as nodal diameters and frequencies. The dynamic response of structures is accompanied by variations in other physical parameters such as temperature, static deformed shapes, speed and torque. A wearing pattern is evaluated following the contact experiments. The spectral content of response is dominated by frequency modes excited by engine orders as well as by sidebands due to inherent system non-linearity.

scholarly journals X-ray Flux and Spectral Variability of the TeV Blazars Mrk 421 and PKS 2155-304

Galaxies ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 64
Author(s):  
Alok C. Gupta
Keyword(s):  
Black Hole ◽  
Time Series Data ◽  
Series Data ◽  
Physical Parameters ◽  
Electromagnetic Spectrum ◽  
Black Hole Mass ◽  
Spectral Variability ◽  
Massive Black Hole ◽  
X Ray ◽  
Northern And Southern Hemispheres

We reviewed X-ray flux and spectral variability properties studied to date by various X-ray satellites for Mrk 421 and PKS 2155-304, which are TeV emitting blazars. Mrk 421 and PKS 2155-304 are the most X-ray luminous blazars in the northern and southern hemispheres, respectively. Blazars show flux and spectral variabilities in the complete electromagnetic spectrum on diverse timescales ranging from a few minutes to hours, days, weeks, months and even several years. The flux and spectral variability on different timescales can be used to constrain the size of the emitting region, estimate the super massive black hole mass, find the dominant emission mechanism in the close vicinity of the super massive black hole, search for quasi-periodic oscillations in time series data and several other physical parameters of blazars. Flux and spectral variability is also a dominant tool to explain jet as well as disk emission from blazars at different epochs of observations.

Experimental and Numerical Investigations on a Rotating Centrifugal Compressor

2012 ◽  
Author(s):  
Patricio Almeida ◽  
Claude Gibert ◽  
Xavier Leblanc ◽  
Jean-Philippe Ousty ◽  
Fabrice Thouverez
Keyword(s):  
Dynamic Behavior ◽  
Centrifugal Compressor ◽  
Signal Transmission ◽  
Laser Doppler Vibrometer ◽  
Rear Side ◽  
Scanning Laser Doppler Vibrometer ◽  
Advantages And Disadvantages ◽  
Slip Ring ◽  
Compressor Impeller ◽  
Common Technique

Controlling the dynamic behavior of turbomachines requires an experimental validation phase to ensure their safety. The application of two experimental techniques to measure the modal properties of a rotating centrifugal compressor impeller is described in this paper. The impeller was tested in a vacuum chamber with excitation provided by piezoelectric actuators mounted on the rear side of the impeller disk. The most common technique used to measure the dynamic behavior of a rotating structure is based on strain gauges and a telemetry system or a slip ring for signal transmission. Nevertheless, in some cases this method is an intrusive technique that could introduce damping and blade mistiming, and it can also be time consuming to prepare. Strain gauge measurement has been compared to measurements performed under the same conditions by Scanning Laser Doppler Vibrometer associated with a derotator optical system, which allows measurement at fixed points on a rotating part. This work focuses on the study of the dynamic behavior of a centrifugal compressor impeller in view to preparing stator contact interaction tests requiring precise characterization of frequencies and nodal diameters and of the influence of rotation speed and other possible parameters. The advantages and disadvantages of the two methods used have been assessed for this particular application. A correlation between the experiments and the numerical simulations using the finite element method is provided.

scholarly journals Coupled Delft3D-Object Model to Predict Mobility of Munition on Sandy Seafloor

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 330
Author(s):  
Peter C. Chu ◽  
Vinicius S. Pessanha ◽  
Chenwu Fan ◽  
Joseph Calantoni
Keyword(s):  
Experimental Data ◽  
Sediment Transport ◽  
Time Series Data ◽  
Major Axis ◽  
Series Data ◽  
Physical Parameters ◽  
Object Model ◽  
Wave Direction ◽  
Rolling Moment ◽  
Object Mobility

The coupled Delft3D-object model has been developed to predict the mobility and burial of objects on sandy seafloors. The Delft3D model is used to predict seabed environmental factors such as currents, waves (peak wave period, significant wave height, wave direction), water level, sediment transport, and seabed change, which are taken as the forcing term to the object model consisting of three components: (a) physical parameters such as diameter, length, mass, and rolling moment; (b) dynamics of the rolling cylinder around its major axis; (c) an empirical sediment scour model with re-exposure parameterization. The model is compared with the observational data collected from a field experiment from 21 April to 13 May 2013 off the coast of Panama City, Florida. The experimental data contain both object mobility using sector scanning sonars and maintenance divers as well as simultaneous environmental time series data of the boundary layer hydrodynamics and sediment transport conditions. Comparison between modeled and observed data clearly shows the model’s capabilities and limitations.

Extremely peculiar spectrum of the primary component of the eclipsing binary HD 66051

2019 ◽  
Vol 15 (S350) ◽  
pp. 412-414
Author(s):  
E. Niemczura ◽  
P. A. Kołaczek-Szymański ◽  
F. Castelli ◽  
S. Hubrig ◽  
S. P. Järvinen ◽  
...  
Keyword(s):  
Time Series ◽  
Time Series Data ◽  
Primary Component ◽  
Series Data ◽  
Physical Parameters ◽  
Orbital Parameters ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
Chemically Peculiar Stars ◽  
Chemical Peculiarity

AbstractHD 66051 is an eclipsing and spectroscopic double-lined binary (SB2), hosting two chemically peculiar stars: a highly peculiar B star as primary and an Am star as secondary. The investigation of the new high-resolution UVES spectrum of HD 66051 allowed us to decide on the chemical peculiarity type of both components with more reliability. An analysis of TESS photometric time series data will further specify the physical parameters of the stars and the orbital parameters of the system.

scholarly journals Coupled Delft3D-Object Model to Predict Mobility and Burial of Munition on Sandy Floor

2021 ◽  
Author(s):  
Peter C. Chu ◽  
Vinicius S. Pessanha ◽  
Chenwu Fan
Keyword(s):  
Sediment Transport ◽  
Time Series Data ◽  
Development Program ◽  
Environmental Research ◽  
Series Data ◽  
Physical Parameters ◽  
Object Model ◽  
Wave Direction ◽  
Peak Period ◽  
Rolling Moment

Coupled Delft3D-object model has been developed to predict object’s mobility and burial on sandy seafloor. The Delft3D model is used to predict seabed environment such as currents, waves (peak period, significant wave height, wave direction), water level, sediment transport, and seabed change, which are taken as the forcing term to the object model consisting of three components: (a) object‘s physical parameters such as diameter, length, mass, and rolling moment, (b) dynamics of rolling cylinder around its major axis, and (c) empirical sediment scour model with re-exposure parameterization. The model is compared with the observational data collected from a field experiment from 21 April to 23 May 2013 off the coast of Panama City, Florida funded by the Department of Defense Strategic Environmental Research and Development Program. The experimental data contain both objects’ mobility using sector scanning and pencil beam sonars and simultaneous environmental time series data of the boundary layer hydrodynamics and sediment transport conditions. Comparison between modeled and observed data clearly show the model capability.

Application of Real-time Monitoring Buoy Systems for Physical and Biogeochemical Parameters in the Coastal Ocean around the Korean Peninsula

2005 ◽  
Vol 39 (2) ◽  
pp. 70-80 ◽  
Author(s):  
SungHyun Nam ◽  
Guebuem Kim ◽  
Kyung-Ryul Kim ◽  
Kuh Kim ◽  
Lawrence Oh Cheng ◽  
...  
Keyword(s):  
Real Time ◽  
Korean Peninsula ◽  
Time Series Data ◽  
Coastal Region ◽  
Series Data ◽  
Physical Parameters ◽  
Potential Contribution ◽  
Coastal Regions ◽  
Frequency Monitoring ◽  
Monitoring Buoy

We introduce technological achievements while developing real-time ocean monitoring buoy systems in the key coastal regions around the Korean peninsula, and highlight their potential contribution to oceanographic studies in the region. Major achievements are an integration of physical and biogeochemical sensors, real-time and two-way communication, sustainable maintenance with stable power supply and mooring design, and the two-way control of sensor and sampling strategies with high sampling rates (as often as every minute). The time-series data from two buoy systems deployed in the key coastal regions are given as examples to show their potential use in studying oceanographic issues, such as major current variations along the east coast of Korea, wind-driven episodic events including typhoon passages, and frequent changes due to internal wave passages. The real-time and high-frequency monitoring of biogeochemical properties of seawater together with physical parameters could be used for numerous oceanographic studies in the coastal region, i.e., air-sea gas exchange, harmful dinoflagellate bloom, interaction between physical and biogeochemical processes.

Graphical Exploratory Data Analysis for Categorical Longitudinal and Time Series Data

2013 ◽  
Author(s):  
Stephen J. Tueller ◽  
Richard A. Van Dorn ◽  
Georgiy Bobashev ◽  
Barry Eggleston
Keyword(s):  
Time Series ◽  
Data Analysis ◽  
Exploratory Data Analysis ◽  
Time Series Data ◽  
Series Data ◽  
Exploratory Data

Some statistical and CI models to predict chaotic high-frequency financial data

2020 ◽  
Vol 39 (5) ◽  
pp. 6419-6430
Author(s):  
Dusan Marcek
Keyword(s):  
Time Series Data ◽  
Moving Average ◽  
Methodological Approach ◽  
Back Propagation ◽  
Large Data ◽  
Series Data ◽  
Data Set ◽  
Training Time ◽  
Optimal Population ◽  
Forecast Time

To forecast time series data, two methodological frameworks of statistical and computational intelligence modelling are considered. The statistical methodological approach is based on the theory of invertible ARIMA (Auto-Regressive Integrated Moving Average) models with Maximum Likelihood (ML) estimating method. As a competitive tool to statistical forecasting models, we use the popular classic neural network (NN) of perceptron type. To train NN, the Back-Propagation (BP) algorithm and heuristics like genetic and micro-genetic algorithm (GA and MGA) are implemented on the large data set. A comparative analysis of selected learning methods is performed and evaluated. From performed experiments we find that the optimal population size will likely be 20 with the lowest training time from all NN trained by the evolutionary algorithms, while the prediction accuracy level is lesser, but still acceptable by managers.

Faktor-Faktor Yang Mempengaruhi Nilai Tukar Dollar Amerika Serikat Terhadap Rupiah Tahun 2000–2013

2017 ◽  
Vol 1 (2) ◽  
pp. 177-191
Author(s):  
Rizki Rahma Kusumadewi ◽  
Wahyu Widayat
Keyword(s):  
Time Series ◽  
Exchange Rate ◽  
Money Supply ◽  
Time Series Data ◽  
The United States ◽  
Economic Conditions ◽  
Series Data ◽  
Arch Model ◽  
United States Dollar ◽  
The Exchange Rate

Exchange rate is one tool to measure a country’s economic conditions. The growth of a stable currency value indicates that the country has a relatively good economic conditions or stable. This study has the purpose to analyze the factors that affect the exchange rate of the Indonesian Rupiah against the United States Dollar in the period of 2000-2013. The data used in this study is a secondary data which are time series data, made up of exports, imports, inflation, the BI rate, Gross Domestic Product (GDP), and the money supply (M1) in the quarter base, from first quarter on 2000 to fourth quarter on 2013. Regression model time series data used the ARCH-GARCH with ARCH model selection indicates that the variables that significantly influence the exchange rate are exports, inflation, the central bank rate and the money supply (M1). Whereas import and GDP did not give any influence.

Sign in / Sign up

Export Citation Format

Share Document