A Type of Flame-Excited Oscillation in a Tube

1957 ◽  
Vol 24 (3) ◽  
pp. 333-339
Author(s):  
J. J. Bailey
Keyword(s):  
Experimental Results ◽  
Driving Mechanism ◽  
Dimensional Theory ◽  
One Dimensional ◽  
Excited Oscillation ◽  
Damping Effects ◽  
Good Agreement

Abstract Propane-air mixtures were burned in an effectively open-ended tube containing a screen flameholder. Two types of instability were observed. Of these, one is described in some detail. A driving mechanism is proposed and examined in the light of Rayleigh’s criterion. Finally, a linear, one-dimensional theory is presented, taking into account both the driving and damping effects in the system. The predictions of this theory are shown to be in good agreement with the experimental results.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

scholarly journals Quantitative Experimental and Theoretical Investigations on the Interaction of Shock Waves with Magnetic Fields

1969 ◽  
Vol 24 (10) ◽  
pp. 1449-1457
Author(s):  
H. Klingenberg ◽  
F. Sardei ◽  
W. Zimmermann
Keyword(s):  
Magnetic Fields ◽  
Shock Waves ◽  
Physical Model ◽  
Spectroscopic Method ◽  
Experimental Results ◽  
Dimensional Theory ◽  
One Dimensional ◽  
Theoretical Investigations ◽  
Theoretical Predictions ◽  
Interaction Of Shock Waves

Abstract In continuation of the work on interaction between shock waves and magnetic fields 1,2 the experiments reported here measured the atomic and electron densities in the interaction region by means of an interferometric and a spectroscopic method. The transient atomic density was also calculated using a one-dimensional theory based on the work of Johnson3 , but modified to give an improved physical model. The experimental results were compared with the theoretical predictions.

The mmW Band Tamm States in One-Dimensional Magnetophotonic Crystals

2009 ◽  
Vol 152-153 ◽  
pp. 394-396 ◽  
Author(s):  
Sergey I. Tarapov ◽  
M. Khodzitskiy ◽  
S.V. Chernovtsev ◽  
D. Belosorov ◽  
A.M. Merzlikin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Theoretical Prediction ◽  
Experimental Results ◽  
One Dimensional ◽  
Magnetophotonic Crystals ◽  
Good Agreement

The mmW band photonic Tamm states in 1D magnetophotonic crystals are studied. It is shown the possibility to manipulate the eigenfrequencies of such states by an external magnetic field. Our experimental results are in a good agreement with theoretical prediction.

One-dimensional overlap functions and their application to Auger recombination in semiconductors

1960 ◽  
Vol 258 (1295) ◽  
pp. 486-495 ◽  
Keyword(s):  
Auger Recombination ◽  
Elevated Temperatures ◽  
Bloch Wave ◽  
Wave Functions ◽  
General Analysis ◽  
Experimental Results ◽  
Overlap Integrals ◽  
Recombination Mechanism ◽  
One Dimensional ◽  
Good Agreement

The theoretical lifetime of excess carriers in semiconductors limited only by the Auger recombination mechanism previously discussed by the present authors, depends on a temperature-independent parameter. This involves certain overlap integrals. They are of the form ∫ u *(k 1 , r) u (k 2 , r) dr, where the u ’s are the modulating parts of Bloch wave functions. The integrals are calculated in this paper on the basis of a Kronig-Penney model. The value of the parameter obtained is shown to be rather insensitive to many details of the model used. When the value found is inserted into the previously published theory of lifetimes in InSb, very good agreement is obtained with the more detailed experimental results which have recently become available. This strongly suggests that the dominant recombination mechanism in InSb at elevated temperatures has been identified. A more general analysis of the properties of the overlap integrals is also given in this paper.

Instability of Elastically Suspended Tainter-Gate System Caused by Surface Waves on the Reservoir of a Dam

1977 ◽  
Vol 99 (4) ◽  
pp. 699-708 ◽  
Author(s):  
Noriaki Ishii ◽  
Kensaku Imaichi ◽  
Akio Hirose
Keyword(s):  
Surface Waves ◽  
Dynamical Behavior ◽  
The Self ◽  
Excited Oscillation ◽  
Gate System ◽  
Damping Effects ◽  
Theoretical Results ◽  
Good Agreement

In this study, it is theoretically shown that an elastically suspended Tainter-gate system with damping effects possesses the property of a self-excited oscillation, provided that the center of the curved weir plate is not in agreement with the location of the trunnion pin. Moreover, the theoretically obtained characteristics for the self-excited oscillation are confirmed with experiments, and it is shown that the theoretical results are in good agreement with experiments. It is concluded that when designing a dam system with Tainter-gates or other similar devices, more interest and attention to the dynamical behavior of Tainter-gates should be taken in order to prevent disasters such as that which occurred in Japan.

One Dimensional Modeling of Catalyst for Internal Combustion Engine Simulation

2006 ◽  
Author(s):  
David Chalet ◽  
Jose´ Galindo ◽  
He´ctor Climent
Keyword(s):  
Shock Wave ◽  
Steady Flow ◽  
Experimental Test ◽  
Test Bench ◽  
Experimental Tests ◽  
Experimental Results ◽  
One Dimensional ◽  
Set Up ◽  
Experimental Test Bench ◽  
Good Agreement

The aim of this paper consists of establishing a methodology for oxidation catalyst modeling based on experimental tests and the development of a theoretical model with zero and one dimensional elements. Related to the theoretical work, the main aspects of such modeling are presented. It consists of describing the inner catalyst geometry by a combination of volumes and simple pipes network. The gas properties in volumes are calculated with a filling and emptying approach whereas the unsteady flow in pipes elements is considered to be one-dimensional and solved by using a finite difference scheme. Concerning the experimental tests, a study is carried out on a shock tube bench. The advantage of this experimental test bench is to study the propagation of a shock wave in the catalyst under controlled and convenient conditions, i.e. cold and non steady flow. Later, the model is set up by comparing the upstream and downstream pressure signals with the simulation results. Since the model lacks of relevant information of pressure losses at the inlet and outlet of the channels, which are rather difficult to compute due to the complex phenomena and flow maldistributions if the use of a 3D CFD code is avoided, the calibration of the model to match the experimental data is the decided approach. In this context, the shock wave test bench is used in order to excite the catalyst with non-steady flow conditions rather than to reproduce the conditions that will appear in real engine operation. The comparison shows good agreement between one-dimensional and experimental results. In order to validate this new modeling on a real engine configuration, an experimental validation is carried out in a four-stroke turbocharged Diesel engine. This experimental test bench allows to measure the main engine characteristics and performance as well as the instantaneous pressure upstream and downstream the catalyst. A simulation code has been also set up to model the engine and the comparison in terms of exhaust pressure pulses propagation inside the catalyst shows good agreement between the one-dimensional model and the experimental results.

Experiments and Modeling of the Heat Transfer of In-Line Square Pin Fin Heat Sinks With Top By-Pass Flow

2002 ◽  
Author(s):  
M. Baris Dogruoz ◽  
Mario Urdaneta ◽  
Alfonso Ortega
Keyword(s):  
Heat Transfer ◽  
Experimental Results ◽  
Heat Sinks ◽  
Transfer Coefficients ◽  
Clearance Ratio ◽  
One Dimensional ◽  
Pin Fin ◽  
Heat Transfer Coefficients ◽  
Approach Velocity ◽  
Good Agreement

This paper presents experimental results on the heat transfer characteristics of in-line square pin fin heat sinks with and without top by-pass. A self-consistent set of aluminum heat sinks were utilized, where the pin height was varied from 12.5 mm to 22.5 mm, the pin pitch was varied from 3.4 mm to 5.8 mm and the base dimensions were kept fixed at 25 × 25 mm. The overall base to ambient thermal resistance was measured as a function of Reynolds number and bypass height. Experimental results were then compared with predictions based on a simple one-dimensional “two-branch by-pass model”. Comparisons were made with the data using heat transfer coefficients available in the literature for infinitely long tube bundles. It was shown that there is a good agreement between the temperature predictions based on the model and the experimental data at high approach velocities for tall heat sinks, however the discrepancy between the computations and experiments increases as the approach velocity and heat sink height decrease. The validated model was used to identify optimum pin spacing as a function of clearance ratio.

Pulse Propagation in Straight and Curved Beams—Theory and Experiment

1974 ◽  
Vol 41 (1) ◽  
pp. 71-76 ◽  
Author(s):  
F. B. Crowley ◽  
J. W. Phillips ◽  
C. E. Taylor
Keyword(s):  
Method Of Characteristics ◽  
Pulse Propagation ◽  
Curved Beam ◽  
Curved Beams ◽  
Dimensional Theory ◽  
One Dimensional ◽  
Isochromatic Fringe ◽  
Fringe Patterns ◽  
Theory And Experiment ◽  
Good Agreement

The equations from Morley’s one-dimensional theory governing the motion of a curved beam subjected to an arbitrary pulse are solved numerically using the method of characteristics. Propagation of initially longitudinal pulses in beam assemblages with both straight and curved sections is investigated. Simulated isochromatic fringe patterns are constructed by a Calcomp plotter and are compared with actual photoelastic patterns. Remarkably good agreement is found between theory and experiment in all the cases investigated. It is concluded that Morley’s theory can be applied to pulse propagation problems of the type investigated.

scholarly journals Image Converter and Intensiner Investigations on Luminous Fronts (Ionizing Waves) in Nitrogen Discharges in a Homogeneous Field

1971 ◽  
Vol 26 (4) ◽  
pp. 700-706 ◽  
Author(s):  
J. Koppitz
Keyword(s):  
Experimental Results ◽  
Homogeneous Field ◽  
Image Converter ◽  
Streamer Discharge ◽  
Time Resolved ◽  
One Dimensional ◽  
Space And Time ◽  
Townsend Discharge ◽  
Theoretical Considerations ◽  
Good Agreement

Abstract In this paper optical space and time resolved measurements on the later development of Kanal (streamer) and Townsend discharges in nitrogen are treated. In both discharges fast luminous fronts (the so called ionizing waves) arise: in the streamer discharge between the primary streamer stage and the spark stage, and in the Townsend discharge during the transition to the glow. For the streamer discharge new experimental results are given, especially at high overvoltages. In the case of the Townsend discharge the development of an idealized, nearly one dimensional dis­charge is treated. The experimental results are in good agreement with theoretical considerations. In contrast to this idealized discharge often strong constrictions are found during the development to the glow, so that the discharge becomes nearly filamentary. The reasons for this behaviour are discussed and the way to avoid it.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

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