On Blade Damping Technology Using Passive Piezoelectric Dampers

2012 ◽  
Author(s):  
Sebastian M. Schwarzendahl ◽  
Jaroslaw Szwedowicz ◽  
Marcus Neubauer ◽  
Lars Panning ◽  
Jörg Wallaschek
Keyword(s):  
Mode Shape ◽  
Mechanical Strain ◽  
Piezoelectric Element ◽  
Measured Data ◽  
Experimental Investigations ◽  
Response Functions ◽  
Ambient Conditions ◽  
Optimal Position ◽  
Measured Frequency Response ◽  
Good Agreement

This paper deals with a new damping concept for turbine blade vibrations utilizing piezoelectric material. A passive piezo damper consists of a piezoelectric element and a passive electric network connected to its electrodes. The damping performance depends on the size and location of the piezoelectric element with respect to the mode shape of the mechanical strain. Numerical and experimental investigations are carried out on a rigidly clamped simplified compressor blade at stand still and ambient conditions. An optimization process incorporating electromechanical finite element calculations determines the optimal position of the piezo damper in regard to the mode shape of interest. By applying the computed and measured Frequency Response Functions, the damping performance with and without piezo-damper are compared and referred to the measured material damping. The obtained numerical results are in very good agreement with the measured data, leading to a promising damping performance in real application.

Investigations on Transonic Flow of Super-Critical CO2 Through Carbon Ring Seals

2015 ◽  
Author(s):  
Eike Hylla ◽  
Markus Schildhauer ◽  
Richard Büssow ◽  
Kolja Metz ◽  
Robert Klawes
Keyword(s):  
Test Procedure ◽  
Measured Data ◽  
Temperature Deformation ◽  
Experimental Investigations ◽  
Real Gas ◽  
Real Gas Effect ◽  
Flow Through ◽  
Co2 Flow ◽  
Gas Effect ◽  
Good Agreement

This paper gives an overview of numerical and experimental investigations on super-critical CO2 flow through carbon floating ring seals (CRS). The established simulation model considers the real gas effect, temperature deformation and the shaft rotation. For validation extensive measurements of the leakage rates, pressures and temperatures at various positions within the seal were conducted on a compressor prototype. Details of the measurement setup and the test procedure are given. The experimental results are discussed. A comparison of the measured data to the model prediction shows an overall good agreement.

A Modified Surface Spline for Expansion and Smoothing of Frequency Response Functions

1996 ◽  
Vol 210 (1) ◽  
pp. 77-92
Author(s):  
T P Waters ◽  
N A J Lieven
Keyword(s):  
Frequency Response ◽  
Model Updating ◽  
Measured Data ◽  
Fe Model ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Surface Spline ◽  
Measured Frequency Response ◽  
Modified Surface ◽  
Noise Contamination

Measured frequency response functions (FRFs) are becoming more widely used to correlate finite element (FE) models with test structures. However, most model updating techniques require measured data at every degree of freedom (DOF) in the FE model, a necessity that is rarely met by experiment. Furthermore, the sensitivity of updating techniques to noise measurement demands experimental data of the highest attainable quality, and often beyond. A modified surface spline is presented which can expand measured FRFs to unmeasured DOFs and also apply smoothing to reduce noise contamination.

Packing Effect on the Transfer Integrals and Mobility in α,α′-bis(dithieno[3,2-b:2′,3′-d]thiophene) (BDT) and its Heteroatom-Substituted Analogues

2011 ◽  
Vol 64 (12) ◽  
pp. 1587 ◽  
Author(s):  
Ahmad Irfan ◽  
Abdullah G. Al-Sehemi ◽  
Shabbir Muhammad ◽  
Jingping Zhang
Keyword(s):  
Electron Transfer ◽  
Electron Mobility ◽  
Hole Mobility ◽  
Experimental Investigations ◽  
Hole Transfer ◽  
Space Group ◽  
Space Groups ◽  
Transfer Integrals ◽  
Packing Effect ◽  
Good Agreement

Theoretically calculated mobility has revealed that BDT is a hole transfer material, which is in good agreement with experimental investigations. The BDT, NHBDT, and OBDT are predicted to be hole transfer materials in the C2/c space group. Comparatively, hole mobility of BHBDT is 7 times while electron mobility is 20 times higher than the BDT. The packing effect for BDT and designed crystals was investigated by various space groups. Generally, mobility increases in BDT and its analogues by changing the packing from space group C2/c to space groups P1 or . In the designed ambipolar material, BHBDT hole mobility has been predicted 0.774 and 3.460 cm2 Vs–1 in space groups P1 and , which is 10 times and 48 times higher than BDT (0.075 and 0.072 cm2 Vs–1 in space groups P1 and ), respectively. Moreover, the BDT behaves as an electron transfer material by changing the packing from the C2/c space group to P1 and .

scholarly journals Validation of MATLAB algorithm to implement a two-step parallel pyrolysis model for the prediction of maximum %char yield

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Ibiba Taiwo Horsfall ◽  
Macmanus Chinenye Ndukwu ◽  
Fidelis Ibiang Abam ◽  
Ololade Moses Olatunji ◽  
Ojong Elias Ojong ◽  
...  
Keyword(s):  
Experimental Data ◽  
Isothermal Condition ◽  
Char Yield ◽  
Experimental Investigations ◽  
Time Saving ◽  
Pyrolysis Products ◽  
Pyrolysis Model ◽  
Experimental Yield ◽  
By Products ◽  
Good Agreement

AbstractNumerical modeling of biomass pyrolysis is becoming a cost and time-saving alternative for experimental investigations, also to predict the yield of the by-products of the entire process. In the present study, a two-step parallel kinetic model was used to predict char yield under isothermal condition. MATLAB ODE45 function codes were employed to solve a set of differential equations that predicts the %char at varying residence times and temperatures. The code shows how the various kinetic parameters and mass of pyrolysis products were determined. Nevertheless, the algorithm used for the prediction was validated with experimental data and results from past works. At 673.15 K, the numerical simulation using ODE45 function gives a char yield of 27.84%. From 573.15 K to 673.15 K, char yield ranges from 31.7 to 33.72% to 27.84% while experimental yield decreases from 44 to 22%. Hence, the error between algorithm prediction and experimental data from literature is − 0.26 and 0.22. Again, comparing the result of the present work with the analytical method from the literature showed a good agreement.

Use of a three-dimensional model to predict heavy metal (copper) fluxes in the Oujiang estuary

2014 ◽  
Vol 69 (6) ◽  
pp. 1334-1343 ◽  
Author(s):  
Shasha Lu ◽  
Ruijie Li ◽  
Xiaoming Xia ◽  
Jun Zheng
Keyword(s):  
River Discharge ◽  
Water Surface ◽  
Three Dimensional ◽  
Measured Data ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Pollutant Concentrations ◽  
Suspended Sediment Concentrations ◽  
Adsorption Desorption ◽  
Good Agreement

Measuring pollutant concentrations in major tributaries is the standard method for establishing pollutant fluxes to the sea. However, this method is costly and difficult, and may be subject to a great deal of uncertainty due to the presence of unknown sources. This uncertainty presents challenges to managers and scientists in reducing contaminant discharges to water bodies. As one less costly method, a three-dimensional model was developed and used to predict pollutant fluxes to the sea. The sorptive contaminant model was incorporated into hydrodynamic and sediment models. Adsorption–desorption of copper by sediments in the Oujiang estuary were described using Henry's law. The model was validated using measured data for water surface elevations, flow velocity/direction, suspended sediment concentrations, and the proportion of copper sorbed to sediment. The validated model was then applied to predict fluxes of copper. Combined with the measured data, the copper concentration in the Oujiang River discharge was calculated as 13.0 μg/L and copper fluxes were calculated as 52 t in 2010. This copper flux prediction was verified using measured dissolved copper concentrations. Comparisons between the modeled and measured results showed good agreement at most stations, demonstrating that copper flux prediction in the Oujiang estuary was reasonably accurate.

Calculation of Component Mode Synthesis Matrices From Measured Frequency Response Functions, Part 2: Application

1998 ◽  
Vol 120 (2) ◽  
pp. 509-516 ◽  
Author(s):  
J. A. Morgan ◽  
C. Pierre ◽  
G. M. Hulbert
Keyword(s):  
Frequency Response ◽  
Coupled System ◽  
Companion Paper ◽  
Component Mode Synthesis ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Measured Frequency ◽  
Measured Frequency Response ◽  
Coupled Beams ◽  
The Individual

This paper demonstrates how to calculate Craig-Bampton component mode synthesis matrices from measured frequency response functions. The procedure is based on a modified residual flexibility method, from which the Craig-Bampton CMS matrices are recovered, as presented in the companion paper, Part I (Morgan et al., 1998). A system of two coupled beams is analyzed using the experimentally-based method. The individual beams’ CMS matrices are calculated from measured frequency response functions. Then, the two beams are analytically coupled together using the test-derived matrices. Good agreement is obtained between the coupled system and the measured results.

Numerical and Experimental Investigations on Preload Effects in Air Foil Journal Bearings

2017 ◽  
Author(s):  
Marcel Mahner ◽  
Pu Li ◽  
Andreas Lehn ◽  
Bernhard Schweizer
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Compressible Fluids ◽  
Experimental Investigations ◽  
Hysteresis Curves ◽  
Numerical Predictions ◽  
Bearing Stiffness ◽  
Gasdynamic Model ◽  
Good Agreement

A detailed elasto-gasdynamic model of a preloaded three-pad air foil journal bearing is presented. Bump and top foil deflections are herein calculated with a nonlinear beamshell theory according to Reissner. The 2D pressure distribution in each bearing pad is described by the Reynolds equation for compressible fluids. With this model, the influence of the assembly preload on the static bearing hysteresis as well as on the aerodynamic bearing performance is investigated. For the purpose of model validation, the predicted hysteresis curves are compared with measured curves. The numerically predicted and the measured hysteresis curves show a good agreement. The numerical predictions exhibit that the assembly preload increases the bearing stiffness (in particular for moderate shaft displacements) and the bearing damping.

scholarly journals Coupled Dynamics of Cable-Harnessed Structures: Experimental Validation

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Karthik Yerrapragada ◽  
Armaghan Salehian
Keyword(s):  
Experimental Study ◽  
Partial Differential Equations ◽  
Frequency Response ◽  
Experimental Validation ◽  
Response Functions ◽  
Beam Structure ◽  
Coupled Dynamics ◽  
Coupled Partial Differential Equations ◽  
Offset Distance ◽  
Good Agreement

The experimental study and model validations for the coupled dynamics of a cable-harnessed beam structure are presented. The system under consideration consists of multiple pretensioned cables attached along the length of the host beam structure positioned at an offset distance from the beam centerline. Analytical model presented by the coupled partial differential equations (PDEs) for various coordinates of vibrations is found, and the displacement frequency response functions (FRFs) obtained for both Euler–Bernoulli and Timoshenko-based models are compared to those from the experiments for validation. The results are shown to be in very good agreement with the experiments.

scholarly journals ∆E/∆E Measurements of Energetic Ions Using CVD Diamond Detectors

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Ahmed Alghamdi ◽  
Lawrence Heilbronn ◽  
Luis A. Castellanos ◽  
Eric Lukosi
Keyword(s):  
Detection System ◽  
National Laboratory ◽  
Cvd Diamond ◽  
Brookhaven National Laboratory ◽  
Measured Data ◽  
Geant4 Simulation ◽  
Computational Results ◽  
Energetic Ions ◽  
Radiation Laboratory ◽  
Good Agreement

Experimental and computational results of a ΔE/ΔE diamond detection system are presented. The ΔE/ΔE detection system was evaluated using energetic proton and iron beams striking thick polyethylene targets at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL). The measured data for diamond sensor A show good agreement with the Geant4 simulation. In addition, simulations have demonstrated the ability to identify hydrogen isotopes using a diamond detection system.

The Effect of Steel Slag Coarse Aggregate on the Mechanical and Durability Performances of Concrete

2020 ◽  
Vol 833 ◽  
pp. 228-232
Author(s):  
Md. Jihad Miah ◽  
Mohammad Shamim Miah ◽  
Anisa Sultana ◽  
Taukir Ahmed Shamim ◽  
Md Ashraful Alom
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Water Absorption ◽  
Coarse Aggregate ◽  
Steel Slag ◽  
Experimental Investigations ◽  
Clay Brick ◽  
Crushing Strength ◽  
Burnt Clay ◽  
Good Agreement

This work performs experimental investigations on concrete made with difference replacement percentage of first-class burnt clay brick aggregate (0, 10, 20, 30, 40, 50, 60, 80, and 100%) by steel slag (SS) aggregate. The aim is to evaluate the mechanical properties as well as durability performances, additionally, water absorption porosity test is performed to investigate the influence of steel slag aggregate on the durability of tested concrete. The experimental results have shown that the compressive strength was improved significantly due to the replacement of brick aggregate by steel slag aggregate. The crushing strength of concrete made with 100% steel slag aggregate has gained up to 70% more than the control concrete (100% brick aggregate). However, the porosity of concrete was reduced with the adding percentage of brick aggregate by steel slag aggregate which is consistent with the compressive strength results. Further, a quite good agreement between compressive strength and porosity was observed as well.

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