The Dynamics of Vortex Amplifiers. Part 2: Dynamic Measurements and Comparison With Model Predictions

1985 ◽  
Vol 107 (3) ◽  
pp. 182-186
Author(s):  
R. F. Boucher ◽  
E. E. Kitsios
Keyword(s):  
Theoretical Model ◽  
Pressure Perturbation ◽  
Hot Wire ◽  
Dynamic Measurements ◽  
Experimental Procedure ◽  
Dual Channel ◽  
Flow Response ◽  
Model Predictions ◽  
General Experimental Procedure ◽  
Measured Pressure

A general experimental procedure is described for determining the linearized transfer admittances of a vortex amplifier. Flow response at the ports to a measured pressure perturbation applied to any one of them was obtained by hot wire anemometer. Self and transfer admittances were determined using a dual channel spectrum analyzer. The difficulties involved in such experiments are discussed. Measurements at two working points compare well with those predicted by the theoretical model developed in Part 1 of this paper.

scholarly journals Experimental Methodology to Determine Thermal Conductivity of Nanofluids by Using a Commercial Transient Hot-Wire Device

2021 ◽  
Vol 12 (1) ◽  
pp. 329
Author(s):  
Jose I. Prado ◽  
Uxía Calviño ◽  
Luis Lugo
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Theoretical Model ◽  
Ethylene Glycol ◽  
Experimental Methodology ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Experimental Procedure ◽  
Transfer Processes ◽  
The Mean

The lack of a standard experimental procedure to determine thermal conductivity of fluids is noticeable in heat transfer processes from practical and fundamental perspectives. Since a wide variety of techniques have been used, reported literature data have huge discrepancies. A common practice is using manufactured thermal conductivity meters for nanofluids, which can standardize the measurements but are also somewhat inaccurate. In this study, a new methodology to perform reliable measurements with a recent commercial transient hot-wire device is introduced. Accordingly, some extensively studied fluids in the literature (water, ethylene glycol, ethylene glycol:water mixture 50:50 vol%, propylene glycol, and n-tetradecane) covering the range 0.100 to 0.700 W m−1 K−1 were used to check the device in the temperature range 283.15 to 333.15 K. Deviations between the collected data and the theoretical model, and repeatabilities and deviations between reported and literature values, were analyzed. Systematic deviations in raw data were found, and a correction factor depending on the mean thermal conductivity was proposed to operate with nanofluids. Considering all tested effects, the expanded (k = 2) uncertainty of the device was set as 5%. This proposed methodology was also checked with n-hexadecane and magnesium-oxide-based n-tetradecane nanofluids.

Hydraulic Driven Rotating Flexible Beam: Theoretical Modal Analysis and Proportional Servo Drive Parameter Influence

2003 ◽  
Author(s):  
Javier Freire ◽  
Esteve Codina ◽  
Munir Khamashta
Keyword(s):  
Theoretical Model ◽  
Modal Analysis ◽  
Dynamic Performance ◽  
Normal Modes ◽  
Flexible Beam ◽  
Servo Drive ◽  
Analysis Methodology ◽  
Model Predictions ◽  
Hydraulic Servo ◽  
Machine Elements

Understanding the behavior of system with flexible elements is increasingly important in modern day technology. Reducing the mass of machine elements leads to a remarkable improvement in dynamic performance. However, a loss of precision also occurs with such an increase in flexibility. In order to arrive at a better understanding of systems with flexible elements, we are investigating the particular behavior of a hydraulic servo driven rotating flexible beam with the aim of obtaining a methodology that could be applied to a real application. To investigate this behavior, a set of models has been developed. In this paper, a theoretical model, using classical modal analysis methodology, is presented. The flexible beam is modeled in a standard way and the hydraulic servo drive is modeled as a boundary condition. Only normal modes will be investigated. This approach allows considering the servo proportional constant and the cylinder mass. It will be show that the servo proportional constant has low influence in the system eigen frequencies. The theoretical model predictions are validated experimentally.

Firefighter Safety Zones: A Theoretical Model Based on Radiative Heating

1998 ◽  
Vol 8 (2) ◽  
pp. 73 ◽  
Author(s):  
BW Butler ◽  
JD Cohen
Keyword(s):  
Theoretical Model ◽  
Radiant Energy ◽  
General Rule ◽  
Quantitative Information ◽  
Radiative Heating ◽  
Flame Height ◽  
Safety Zone ◽  
Model Predictions ◽  
Zone Radius ◽  
Height Model

Quantitative information regarding safety zone size for wildland firefighters is limited. We present a 3-surface theoretical model that describes the net radiant energy transfer to a firefighter standing a specified distance from a fire of specified height. Model predictions compare favorably with qualitative data from entrapments on four wildfires and two previously published models. Calculations indicate that for most fires, safety zones must be greater than 20 m wide to ensure firefighter survival. A general rule-of-thumb derived from this work is that a safety zone radius must be equal to or greater than 4 times the maximum flame height.

Effects of Aging on Polymerization Kinetics

1990 ◽  
Vol 215 ◽  
Author(s):  
Christopher N. Bowman ◽  
Nikolaos A. Peppas
Keyword(s):  
Relaxation Time ◽  
Theoretical Model ◽  
Light Intensity ◽  
Physical Aging ◽  
Volume Relaxation ◽  
Radical Concentration ◽  
Model Predictions ◽  
Maximum Conversion ◽  
Effects Of Aging ◽  
Crosslinking Reactions

AbstractA theoretical model was developed to describe the physical aging during photopolymerizations and crosslinking reactions of diacrylates and dimethacrylates. The model incorporates the strong coupling between the volume relaxation and the kinetics observed in these reactions. Model predictions are presented for the reaction kinetics, volume relaxation, radical concentration and maximum conversion as a function of light intensity and relaxation time of the polymer.

CW and temporal theoretical model predictions and experimental results for Tm:YAG and Ho:YAG lasers

2008 ◽  
Author(s):  
Eric K. Gorton ◽  
John G. Betterton ◽  
David A. Orchard ◽  
Brian J. Perrett ◽  
Paul D. Mason ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Experimental Results ◽  
Model Predictions

scholarly journals Coupling Reduces Noise: Applying Dynamical Coupling to Reduce Local White Additive Noise

2015 ◽  
Vol 25 (03) ◽  
pp. 1550040 ◽  
Author(s):  
Behnam Kia ◽  
Sarvenaz Kia ◽  
John F. Lindner ◽  
Sudeshna Sinha ◽  
William L. Ditto
Keyword(s):  
Theoretical Model ◽  
Dynamical Systems ◽  
Noise Level ◽  
Additive Noise ◽  
Nonlinear Dynamical Systems ◽  
Coupled Map Lattices ◽  
Nonlinear Dynamical ◽  
Model Predictions ◽  
Dynamical Coupling ◽  
Averaging Filter

We demonstrate how coupling nonlinear dynamical systems can reduce the effects of noise. For simplicity we investigate noisy coupled map lattices and assume noise is white and additive. Noise from different lattice nodes can diffuse across the lattice and lower the noise level of individual nodes. We develop a theoretical model that explains this observed noise evolution and show how the coupled dynamics can naturally function as an averaging filter. Our numerical simulations are in excellent agreement with the model predictions.

Sign in / Sign up

Export Citation Format

Share Document