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See detailEXPERIMENTAL INVESTIGATION OF NOx FORMATION MECHANISMS IN A FUEL-OIL BOILER
Tartari, Paula; Ngendakumana, Philippe ULg

Conference (2002, June)

The work whose results are reported in this paper was aimed at gathering information that can give a deeper insight into the structure of a diffusion fuel-oil flame. This allows us to get a better ... [more ▼]

The work whose results are reported in this paper was aimed at gathering information that can give a deeper insight into the structure of a diffusion fuel-oil flame. This allows us to get a better understanding of the combustion process and thus a correct basis for combustion modeling, focused on NOx formation. In order to attain the objective, axial and radial temperature, NOx and O2 concentration profiles have been measured in the flame for high and low firing rates of a domestic hot water boiler (around 424 and 270 kW respectively). Temperature was measured by means of two B-type thermocouples (diameters 0.5 and 0.35 mm) and NOx and O2 concentrations using a classical gas analyzer. Maximum NOx emissions (167 ppm at 424 kW and 134 ppm at 270 kW) were recorded in high oxygen concentration and low temperature zones of the flame ( ≈ 1000°C), where no thermal-NO can be formed. Flue gas recirculation and NOx destruction process is clearly demonstrated in the flame due to the higher NOx concentrations recorded in the combustion chamber near the burner exit than in the chimney. Near the burner exit NOx, O2 and temperature radial profiles are very unstable. Higher temperature fluctuations were detected with the small thermocouple in the measurements at 270 kW. The contribution of the three types of NOx formation mechanisms was obtained using a simplified model. According to these results, the majority of NOx in this type of flame could be caused by the prompt-NO mechanism, formed in the zone close to the burner exit at the location where secondary combustion air is introduced. [less ▲]

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See detailExperimental investigation of passive/active oxidation behavior of SiC based ceramic thermal protection materials exposed to high enthalpy plasma
Sakraker, Isil ULg; Asma, Cem Ozan

in Journal of the European Ceramic Society (2013), 33(2), 351-359

The passive/active oxidation behavior of a CVD-SiC coated C/C-SiC thermal protection material of the hypersonic SpaceLiner vehicle is investigated experimentally. For the safety of spacecraft and its ... [more ▼]

The passive/active oxidation behavior of a CVD-SiC coated C/C-SiC thermal protection material of the hypersonic SpaceLiner vehicle is investigated experimentally. For the safety of spacecraft and its passengers, it is important to know whether the thermal protection system will experience passive/active oxidation during the vehicle’s entry into Earth’s atmosphere. Active oxidation can promote material loss whereas passive oxidation forms a protective film. The high enthalpy flight conditions of SpaceLiner vehicle are duplicated in VKI Plasmatron, where the samples are exposed to high enthalpy plasma and the surface temperatures increase up to 2800 K at various total pressure (2–20 kPa) conditions. Surface temperature profiles, visual characteristics, mass changes, emissivity, spectrometer and SEM/EDX data are examined to identify the oxidation transition border of the tested material. A temperature jump is observed in all active oxidation regimes. The experimental results are found to be in good agreement with correlations from the literature. [less ▲]

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See detailExperimental investigation of targeted energy transfers in strongly and nonlinearly coupled oscillators
McFarland, D. Michael; Kerschen, Gaëtan ULg; Kowtko, Jeffrey J. et al

in Journal of the Acoustical Society of America (2005), 118(2), 791-799

Our focus in this study is on experimental investigation of the transient dynamics of an impulsively loaded linear oscillator coupled to a lightweight nonlinear energy sink. It is shown that this ... [more ▼]

Our focus in this study is on experimental investigation of the transient dynamics of an impulsively loaded linear oscillator coupled to a lightweight nonlinear energy sink. It is shown that this seemingly simple system exhibits complicated dynamics, including nonlinear beating phenomena and resonance captures. It is also demonstrated that, by facilitating targeted energy transfers to the nonlinear energy sink, a significant portion of the total input energy can be absorbed and dissipated in this oscillator. (C) 2005 Acoustical Society of America. [less ▲]

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See detailExperimental investigation of the aeroacoustic coupling between the non-planar modes of a resonator and the misaligned jet-slot oscillator
Glesser, Martin; Valeau, Vincent; Billon, Alexis ULg et al

in Acta Acustica United with Acustica (2009), 95(3), 512-518

The jet-slot oscillator is a source of aeroacoustic self-sustained tones resulting from the impingement of the vortical structures of a plane jet onto a slotted plate. The coupling of this type of ... [more ▼]

The jet-slot oscillator is a source of aeroacoustic self-sustained tones resulting from the impingement of the vortical structures of a plane jet onto a slotted plate. The coupling of this type of aeroacoustic source with high-order acoustic resonances of the flow-supply duct is experimentally studied, in the particular case where the jet-exit and the obstacle are misaligned in the spanwise direction. An experimental setup based on microphones and hot-wire probes is used to investigate this coupling. It is shown that: (i) the misaligned jet-slot oscillator can be coupled to non-planar (transverse) modes of the flow-supply duct, (ii) the vortex tubes spanwise morphology is governed by the phase pattern of the excited modes, and (iii) the impingement of the vortices on the inclined obstacle tends to occur in phase in the spanwise direction, in order to enhance the coherence of the interaction along the slot. An investigation of the excited modes as a function of the plate inclination angle and of the streamwise slot position was then conducted. For small inclination angles, the coupling involves a planar mode or a combination of planar and transverse modes. For higher misalignment angles the coupling involves transverse modes or “opposite-transverse” modes, generating vortices with an inclination angle opposite to the plate inclination angle. The influence of the coupling nature on tone production (emission frequency and SPL) was thus evaluated. [less ▲]

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See detailExperimental Investigation of the Aerodynamics and Aeroelasticity of Flapping, Plunging and Pitching Wings
Norizham, Abdul Razak ULg

Doctoral thesis (2012)

This thesis concerns the experimental analysis of the aerodynamics and aeroelasticity of oscillating wings. It is divided into two sections, an inves- tigation of wings undergoing imposed root flapping ... [more ▼]

This thesis concerns the experimental analysis of the aerodynamics and aeroelasticity of oscillating wings. It is divided into two sections, an inves- tigation of wings undergoing imposed root flapping and pitching motion, such as seen in avian flight and an experimental investigation of the self- excited stall flutter oscillations of a wing undergoing plunging and pitching motion. The objective of the flapping wing investigation is to improve the under- standing of the unsteady aerodynamics of flapping flight. The work con- sists of designing and building a flapping and pitching bird-like mechanical model and testing it in a low speed wind tunnel. The model’s size is sim- ilar to that of a goose. The wind tunnel tests involved the measurement of forces, power, kinematics and local flow velocities using Particle Im- age Velocimetry (PIV). The mechanical model was tested at four different frequencies and three airspeeds. In addition, three different wing profiles were tested. The kinematic modes included pure flapping and combined flapping and pitching. It was shown that pure flapping and pitch-lagging combined motion can lead to interesting aerodynamic phenomena, such as flow separation and dynamic stall. Dynamic stall can cause significant increases in instantaneous lift production, although it also generates a lot of drag. On the contrary, pitch leading combined motion can generate a net propulsive force over the entire cycle. In the stall flutter study, a 6 degree of freedom NACA 0018 wing was sus- pended by springs in the wind tunnel. The wing was then exposed to an airflow at a number of airspeeds and wind-off angles of attack. The wing was instrumented with pressure sensors and accelerometers. In addition, PIV flow measurements were carried out on the wing’s upper surface. The work demonstrates that stall flutter is the result of a combination of dy- namic stall with the elastic properties of the system. The dynamic stall mechanism was studied using the PIV measurements and was found to be different to the classical stall mechanisms that are reported in the litera- ture. The sensitivity of the stall flutter phenomenon to parameters such as airspeed and wind-off angle of attack is demonstrated by means of a two-parameter bifurcation diagram. [less ▲]

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See detailExperimental investigation of the effect of flip bucket splitters on plunge pool geometry
Erpicum, Sébastien ULg; Archambeau, Pierre ULg; Dewals, Benjamin ULg et al

in Wasserwirtschaft (2010), 4

Flip buckets are common hydraulic structures aiming at deflecting high velocity flows to a free jet trajectory. Systematic experimental tests have been performed to assess the influence on energy ... [more ▼]

Flip buckets are common hydraulic structures aiming at deflecting high velocity flows to a free jet trajectory. Systematic experimental tests have been performed to assess the influence on energy dissipation and the plunge pool geometry of varied repartitions of splitters along the flip bucket width. In particular, it is shown that some configurations can create more erosion than a continuous channel without flip bucket. [less ▲]

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See detailExperimental investigation of the effect of flip bucket splitters on plunge pool geometry
Erpicum, Sébastien ULg; Archambeau, Pierre ULg; Dewals, Benjamin ULg et al

in RWTH - IWW (Ed.) Mitteilungen - 15. Deutsches Talsperrensymposium - Talsperren im Wandel (2010)

Flip buckets are common hydraulic structures aiming at deflecting high velocity flows to a free jet trajectory. Systematic experimental tests have been performed to assess the influence on energy ... [more ▼]

Flip buckets are common hydraulic structures aiming at deflecting high velocity flows to a free jet trajectory. Systematic experimental tests have been performed to assess the influence on energy dissipation and the plunge pool geometry of varied repartitions of splitters along the flip bucket width. In particular, it is shown that some configurations can create more erosion than a continuous channel without flip bucket. [less ▲]

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See detailAn experimental investigation of the subsonic stall flutter
Li, Jing; Andrinopoulos, Nikolaos; Dimitriadis, Grigorios ULg

in Proceedings of the 2006 International Conference on Noise and Vibration Engineering (2006, September)

This paper reports on experimental investigations of the subsonic stall flutter of a wing in a wind tunnel. Stall flutter (also know as Dynamic Stall) is a LCO phenomenon occurring when all or part of the ... [more ▼]

This paper reports on experimental investigations of the subsonic stall flutter of a wing in a wind tunnel. Stall flutter (also know as Dynamic Stall) is a LCO phenomenon occurring when all or part of the flow over a wing separates and re-attaches at least once during a full oscillation period. In order to investigate the aeroelastic effects of the nonlinearity introduced by the boundary layer growth and flow separation and the ensuing stall-induced LCO, a wind tunnel model of a wing undergoing stall flutter is designed, built and tested. The model is a rectangular wing with constant cross-section free to move in the pitch and plunge directions, restrained by torsional and linear springs respectively. The motion of the wing is measured using laser displacement probes. Two types of stall flutter are observed and measured: 1. Non-symmetric stall flutter, where the flow separates over one side of the wing only, and 2. Symmetric stall flutter, where the flow separates over both sides of the wing (deep stall). The bifurcation behaviour of the wing is very complex and both types of LCO can be observed during a single response history. [less ▲]

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See detailExperimental investigation on a decentralized air handling terminal: procedure of aeraulic and thermal performance determination of the entire unit under several operating conditions
Gendebien, Samuel ULg; Prieels, Luc; Lemort, Vincent ULg

in Proceedings of the 6th European Thermal Sciences Conference (2012, September)

A new local ventilation device is actually developed in such a way to procure ventilation “on demand” in each room, with a maximal effectiveness. It consists in a wall or window frame mounted plane ... [more ▼]

A new local ventilation device is actually developed in such a way to procure ventilation “on demand” in each room, with a maximal effectiveness. It consists in a wall or window frame mounted plane-parallel box, containing two (injection and extraction) fans, an electronic control, and a heat recovery exchanger. The present paper describes the experimental investigations carried out on some single components and on the entire unit in order to characterize the aeraulic and thermal performance of the device. [less ▲]

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See detailExperimental investigation on a hermetic scroll expander
Lemort, Vincent ULg; Quoilin, Sylvain ULg; Pire, Christophe

in Proceedings of the 7th International IIR Conference on Compressors (2009, September)

This paper presents the results of an experimental study carried out on a prototype of hermetic scroll expander, integrated into a gas cycle test rig, whose working fluid is R245fa. This system was ... [more ▼]

This paper presents the results of an experimental study carried out on a prototype of hermetic scroll expander, integrated into a gas cycle test rig, whose working fluid is R245fa. This system was designed to test only the performance of the expander. It is mainly made up of a scroll compressor, a scroll expander, a heat exchanger and a by-pass valve. The latter is used to adjust the pressure ratio imposed to the expander. The expander is originally a compressor used for heat pump applications and characterized by a nominal power input of 2.5 kW. Performance of the expander is evaluated in terms of isentropic effectiveness and filling factor as function of the main operating conditions. The study also investigates the impact of oil mass fraction on the expander performance. Using the experimental data, parameters of a simulation model of the expander are identified. The model is finally used to analyze the measured performance of the expander. [less ▲]

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See detailExperimental Investigation on a Reversible Heat Pump for a Passenger Car
Lemort, Vincent ULg; Cuevas, Cristian; Declaye, Sébastien ULg

in Proceedings of the 21st International Compressor Conference, Purdue 2012 (2012, July)

This paper summarizes the first results of a research project dealing with the development of a reversible heat pump for a passenger car. Heat pump systems appear to be a more efficient alternative to ... [more ▼]

This paper summarizes the first results of a research project dealing with the development of a reversible heat pump for a passenger car. Heat pump systems appear to be a more efficient alternative to electrical resistance heaters for the purpose of heating the car indoor environment. Heat pump systems could be easily implemented into cars by allowing the air-conditioning system to run in reverse. In order to check the technical feasibility of a reversible heat pump system, and to point out technical barriers, a prototype was built and tested. Experimental data was also used to calibrate and validate simulation models of components. A heat pump system model was finally built to investigate the operating conditions of the system. The first part of the paper describes the test rig (architecture, components, and measurement devices) and the experimental campaign. Performance of components (compressor, evaporator, condenser and heater core) is evaluated in terms of variation with the operating conditions. The second part of the paper presents the steady-state semi-empirical models of the components. Such lumped models retain and concentrate the main physical phenomena inherent to the components into successive elementary processes (pressure losses, heat transfers, etc.). They require a limited number of parameters that can be identified based on experimental data. The calibration and the validation of the proposed component models are detailed. Finally, an overall simulation model of the reversible heat pump system is proposed and used to evaluate the energy performance of the system as function of the operating conditions. [less ▲]

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See detailExperimental investigation on ferritic stainless steel columns in fire
Tondini, Nicola; Rossi, Barbara; Franssen, Jean-Marc ULg

in Fire Safety Journal (2013)

This paper presents the performance of EN 1.4003 ferritic stainless steel hollow section columns when exposed to fire loading. Experimental analysis of the behaviour of ferritic stainless steel structural ... [more ▼]

This paper presents the performance of EN 1.4003 ferritic stainless steel hollow section columns when exposed to fire loading. Experimental analysis of the behaviour of ferritic stainless steel structural members in fire represents a novelty. In detail, three column tests were carried out in the framework of the RFCS project named Structural Applications of Ferritic Stainless Steels (SAFSS, RFSR-CT-2010-00026). Tubular thin-walled members were considered in this study because structural applications of ferritic stainless steels generally incorporate such profiles. Three columns were tested: two square hollow sections (SHS) and a rectangular hollow section (RHS) of different length. Fire loading was applied under a constant concentrically compressive load. Identical column tests at room temperature are also reported. [less ▲]

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See detailExperimental investigation on plasma temperature of Ca by laser—induced breakdown spectroscopy
Li, Jie ULg; Lu, Jidong; Lin, Zhaoxiang et al

in High Power Laser and Particle Beams (2009), 21(5), 689-693

The )lasma temperature is an important factor in quantitative analysis by laser induced breakdown spectroscopy(LIBS).The plasmas were generated by a Nd:YAG laser 0n the surface of sample and detected by ... [more ▼]

The )lasma temperature is an important factor in quantitative analysis by laser induced breakdown spectroscopy(LIBS).The plasmas were generated by a Nd:YAG laser 0n the surface of sample and detected by an Echelle spectrograph and an Intensified Charge—Couplea Device(ICCD).The spectrum of 300 nm to 450 nm recorded several spectral lines of Ca component such as Ca II 31 5.9 nm.Ca II 317.9 nrn.Ca 1I 393.4 nm,Ca Ⅱ 396.9 nm,Ca I 422.7 nm and so on.It is known that the change of plasma temperature has influence on the line intensity from the equation for quantitative LIBS analysis.It was assumed that the plasm as produced in the experiment were in local thermodynamic equilibrium(LTE).The temperature variations were deduced bv tine four 0ne—ionized Ca spectral lines and the Boltzmann plot,and the relationship between the plasma temperature and the concentration was obtained too.The plasma temperature increased when the concentration increased.When the mass fraction of Ca was lower than 0.50, the increase velocity of the plasma temperature was small. When the mass fraction of Ca was higher than 0.50, the increase was large.The hypothesis of local thermal equilibrium conditions of the plasma was confirmed in this experiment. [less ▲]

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See detailExperimental Investigation on Quantitative Analysis of Glass by Laser Induced Breakdown Spectroscopy
Li, Pengyan; Xie, Chengli; Lu, Jidong et al

in Applied Laser (2009), 29(1), 21-25

Experimental investigation of quantitative analysis of glass by calibration-free laser induced breakdown spectroscopy (CF LIBS)was carried out in this paper.An intense laser radiation with a wavelength of ... [more ▼]

Experimental investigation of quantitative analysis of glass by calibration-free laser induced breakdown spectroscopy (CF LIBS)was carried out in this paper.An intense laser radiation with a wavelength of 1064nm was used to ablate fine glass to form plasma plume, and the emission spectrum emitted as the plasma cooling off was analyzed by high resolution echelle grating spectrometer coupled to Intensified Charge Coupled Device(ICCD)cam era.The results show that the intensity and repeatability of spectrum is best on the condition of laser pulse focused above the surface of sample,and in this experiment the height is about 3 mm. By the CF-I IBS,the relative errors of quantitative analysis of elem ents in glass varied between 3.6% ~11.2 %,and good repeatability with relative standard deviation between 1.6% ~ 7.7% for five measurements was obtained. [less ▲]

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See detailExperimental investigation on the seismic behaviour of masonry housing in low seismicity areas
Degée, Hervé ULg; Plumier, André ULg

in Proceedings of the 1st European Conference on Earthquake Engineering and Seismology (2006)

This contribution presents the results of an experimental investigation carried out on the shaking table of the National Laboratory of Civil Engineering of Lisbon (LNEC), in order to validate the ... [more ▼]

This contribution presents the results of an experimental investigation carried out on the shaking table of the National Laboratory of Civil Engineering of Lisbon (LNEC), in order to validate the efficiency of some constructive proposals aiming at improving the structural behaviour of non engineered masonry housing subjected to low to moderate seismic action, with rather low costs compared to traditional North-European practice. Two specimens have been tested. These specimens were two full-scale small houses with two levels. The first one was built as a traditional Belgian house, while the second included some anti-seismic technical details. The main conclusions are that both specimens were still standing at the maximum earthquake level foreseen for Belgium, but that the improved model was much less damaged regarding crack openings in the walls. Therefore the economic consequences and repair costs would be much lower with these improvements. However the maximum ground acceleration that can be sustained by the structures seems to be very little influenced by the constructional detailing. [less ▲]

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See detailExperimental investigation on the seismic behaviour of north European masonry houses
Degée, Hervé ULg; Denoël, Vincent ULg; Candeias, P. et al

in Proceedings of SISMICA 07, Sismic Congress (2007)

This paper presents the results of shaking table tests performed on two full-scale masonry houses typical from North-European countries. The main objective of the experimental study is to assess the ... [more ▼]

This paper presents the results of shaking table tests performed on two full-scale masonry houses typical from North-European countries. The main objective of the experimental study is to assess the seismic behaviour of such houses for situations of low to moderate seismicity and to investigate the actual effect of some reinforcing details. [less ▲]

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See detailExperimental investigations and analytical models for behavior of Grade 8.8 bolts and butt welds under heating and subsequent cooling
Hanus, François ULg; Zilli, Giuliana; Franssen, Jean-Marc ULg

in kodur, venkatesh; Franssen, Jean-Marc (Eds.) Structures in Fire - Proceedings of the Sixth International Conference (2010, June 03)

The present article describes the experimental tests undertaken on Grade 8.8 tests and butt welds at the Centro Sviluppo Materiali during heating or subsequent cooling, presents a model for the force ... [more ▼]

The present article describes the experimental tests undertaken on Grade 8.8 tests and butt welds at the Centro Sviluppo Materiali during heating or subsequent cooling, presents a model for the force-displacement diagram of bolts during a natural fire that integrates the influence of the temperature history, and gives values of strength reduction factors for the cooling phase [less ▲]

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See detailExperimental investigations of temperature and suction effects on compressibility and pre-consolidation pressure of a sandy silt
Salager, Simon; François, Bertrand ULg; El Youssoufi, M. S. et al

in Soils and Foundations (2008), 48(4), 453-466

Research interest in the thermo-mechanical behaviour of unsaturated soils is growing as a result of an increasing number of geomechanical problems involving both thermal and unsaturated effects. In this ... [more ▼]

Research interest in the thermo-mechanical behaviour of unsaturated soils is growing as a result of an increasing number of geomechanical problems involving both thermal and unsaturated effects. In this framework, this paper addresses a unified thermo-mechanical experimental study of saturated and unsaturated states and, in so doing, contributes to the understanding of the non-isothermal mechanical behaviour of unsaturated soils. The present experimental program has been carried out on a sandy silt called "Sion silt" using two thermo-hydro-mechanical (THM) cells, one isotropic and one oedometric. The characteristics of these two cells are briefly presented, as well as the THM paths followed. The main results are presented and interpreted in the light of a suitable THM constitutive framework. The compressibility of the soil tested appears not to be affected by the temperature but decreases with a suction increase. As far as the apparent preconsolidation stress is concerned, the results show a decrease of the yield limit with increasing temperature, while a suction increase tends to enhance this limit. Finally, an analytical expression is proposed to describe the evolution of the apparent preconsolidation stress with respect to temperature and suction. [less ▲]

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See detailExperimental investigations of the material behavior of Ti6Al4V titanium alloy
Rossi, Barbara ULg; Gilles, Gaëtan ULg; Zolotas, Eric et al

Report (2011)

Computer models are widely used to support the development of conventional design methods based on expensive full-scale tests or trial and error methods. Nevertheless, in order to accurately model metal ... [more ▼]

Computer models are widely used to support the development of conventional design methods based on expensive full-scale tests or trial and error methods. Nevertheless, in order to accurately model metal forming processes as well as structural behavior of load carrying elements, it is necessary to afford an accurate knowledge of the material properties. Titanium is one of the material for which various industrial sectors such as aerospace or biomedical are showing an increasing interest. This paper presents the experimental tests performed on the titanium based alloy Ti6Al4V to investigate on its mechanical behavior, especially in terms of its anisotropy and hardening. For that purpose, a classical uniaxial and a non-standard biaxial experimental equipments designed by Florès in the Materials and Structures Mechanics Laboratory of the University of Liège have been used to perform tensile, simple shear and cyclic shear tests as well as successive simple shear and plane strain tests, which provide the main contribution of this paper in the form of stress-strain curves. [less ▲]

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