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Articles 1 - 6 of 6
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Characterisation Of Porous Materials Viscoelastic Properties Involving The Vibroacoustical Behaviour Of Coated Panels, Olivier Doutres, Nicolas Dauchez
Characterisation Of Porous Materials Viscoelastic Properties Involving The Vibroacoustical Behaviour Of Coated Panels, Olivier Doutres, Nicolas Dauchez
Olivier Doutres Ph.D.
Porous materials are widely used as passive acoustic absorbers. For optimal design, it is often necessary to know the viscoelastic properties of these materials in the frequency range relevant to their application. The viscoelastic properties are obtained by fitting an analytical model to acoustical radiation experimental measurements carried out on a circular coated plate clamped in a rigid baffle. Compared with quasistatic method, the viscoelastic properties are here achieved at high frequency corresponding to the first resonance in the thickness of the porous layer and coupling between porous materials and external fluid is taken into account. The analytical model, developped …
Measurements Of Oh Mole Fraction And Temperature Up To 20 Khz By Using A Diode-Laser-Based Uv Absorption Sensor, Terrence Meyer, Sukesh Roy, Thomas Anderson, Joseph Miller, Vlswanath Katta, Robert Lucht, James Gord
Measurements Of Oh Mole Fraction And Temperature Up To 20 Khz By Using A Diode-Laser-Based Uv Absorption Sensor, Terrence Meyer, Sukesh Roy, Thomas Anderson, Joseph Miller, Vlswanath Katta, Robert Lucht, James Gord
Terrence R Meyer
Diode-laser-based sum-frequency generation of ultraviolet (UV) radiation at 313.5 nm was utilized for high-speed absorption measurements of OH mole fraction and temperature at rates up to 20 kHz. Sensor performance was characterized over a wide range of operating conditions in a 25.4 mm path-length, steady, C2H4-air diffusion flame through comparisons with coherent anti-Stokes Raman spectroscopy (CARS), planar laser-induced fluorescence (PLIF), and a two-dimensional numerical simulation with detailed chemical kinetics. Experimental uncertainties of 5% and 11% were achieved for measured temperatures and OH mole fractions, respectively, with standard deviations of <3% at 20 kHz and an OH detection limit of <1 part per million in a l m path length. After validation in a steady flame, high-speed diode-laser-based measurements of OH mole fraction and temperature were demonstrated for the first time in the unsteady exhaust of a liquid-fueled, swirl-stabilized combustor. Typical agreement of 5% was achieved with CARS temperature measurements at various fuel/air ratios, and sensor precision was sufficient to capture oscillations of temperature and OH mole fraction for potential use with multiparameter control strategies in combustors of practical interest.
Modelling Of The Acoustic Radiation Of A Structure Covered By A Porous Layer, Olivier Doutres, Nicolas Dauchez
Modelling Of The Acoustic Radiation Of A Structure Covered By A Porous Layer, Olivier Doutres, Nicolas Dauchez
Olivier Doutres Ph.D.
In many applications, porous materials such as polymers foams are attached to a structure subjected to vibration. This allows to diminish vibration by increasing structural damping or to reduce noise level in cavities by sound absorption. The radiation efficiency of the coupled system is studied. An analytical model has been carried out, separating the acoustical and vibratory behaviors: - The vibratory analysis is based on a dynamic study of an equivalent plate of the coupled system. In this case the porous layer is considered as a viscoelastic layer. - In the acoustical analysis, a surface impedance is applied on this …
Simultaneous Planar Laser-Induced Incandescence, Oh Planar Laser-Induced Fluorescence, And Droplet Mie Scattering In Swirl-Stabilized Spray Flames, Terrence Meyer, Sukesh Roy, Vincent Belovich, Edwin Corporan, James Gord
Simultaneous Planar Laser-Induced Incandescence, Oh Planar Laser-Induced Fluorescence, And Droplet Mie Scattering In Swirl-Stabilized Spray Flames, Terrence Meyer, Sukesh Roy, Vincent Belovich, Edwin Corporan, James Gord
Terrence R Meyer
Simultaneous planar laser-induced incandescence, hydroxyl radical planar laser-induced fluorescence, and droplet Mie scattering are used to study the instantaneous flame structure and soot formation process in an atmospheric pressure, swirl-stabilized, liquid-fueled, model gas-turbine combustor. Optimal excitation and detection schemes to maximize single-shot signals and avoid interferences from soot-laden flame emission are discussed. The data indicate that rich pockets of premixed fuel and air along the interface between the spray flame and the recirculation zone serve as primary sites for soot inception. Intermittent large-scale structures and local equivalence ratio are also found to play an important role in soot formation.
Failure Analysis Of Superheater Tube Supports Of The Primary Reformer In A Fertilizer Factory
Failure Analysis Of Superheater Tube Supports Of The Primary Reformer In A Fertilizer Factory
A.S. Md Abdul Haseeb
A failure analysis of superheater tube supports of the primary reformer in a local fertilizer factor is presented. A number of tube supports failed at approximately half of their designed service life. Following the failure, the factory was visited, and relevant information and samples were collected. The samples were investigated in the laboratory by chemical analysis, macro- and microhardness measurements, macro-and micrometallographic examinations, and X-ray diffractometry. The analysis showed the supports were fabricated from HH-type heat-resisting alloy and that the failure mode was high-temperature creep. The microstructure of the alloy showed the presence of massive intergranular as well as intragranular …
Design And Development Of Orifice-Type Aerostatic Thrust Bearing, Jitendra P. Khatait
Design And Development Of Orifice-Type Aerostatic Thrust Bearing, Jitendra P. Khatait
Jitendra P Khatait
Air bearings are extensively used in precision machines and equipment in recent years. Unlike conventional bearings, there is no physical contact between the sliding surfaces. The moving surface can glide smoothly on the other surface, minimising the control effort to achieve high accuracy and precision. Analytical study was carried out avoiding complexities in the formulation. The governing parameters were kept at a minimum. This helped in easy understanding of the dynamics and performance behavior of the air bearings. A simple design methodology was also developed to assist in the design or the selection process of the bearing. Finally, a three-dimensional …