The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform
Hassan Peerhossaini - One of the best experts on this subject based on the ideXlab platform.
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Aerodynamic Forces on a Simplified Car Body: Towards Innovative Designs for Car Drag Reduction
ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting: Volume 1 Symposia – Parts A B and C, 2010Co-Authors: Mahmoud Khaled, Fabien Harambat, Anthony Yammine, Hassan PeerhossainiAbstract:The present paper exposes the study of the Cooling system circulation effect on the external aerodynamic forces. We report here aerodynamic force measurements carried out on a simplified vehicle model in wind tunnel. Tests are performed for different airflow configurations in order to detect the parameters that can affect the aerodynamic torsor and to confirm others previously suspected, especially the air inlets localization, the air outlet distributions and the underhood geometry. The simplified model has flat and flexible air inlets and several types of air outlet, and includes in its body a real Cooling system and a simplified engine block that can move in the longitudinal and lateral directions. The results of this research are generic and can be applied to any new car design. Results show configurations in which, with respect to the most commonly adopted underhood geometries, the overall Drag coefficient can be decreased by 2%, the aerodynamic Cooling Drag coefficient by more than 50% and the lift coefficient by 5%. Finally, new designs of aerodynamic Drag reduction, based on the combined effects of the different investigated parameters, are proposed.
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Underhood thermal management: Temperature and heat flux measurements and physical analysis
Applied Thermal Engineering, 2010Co-Authors: Mahmoud Khaled, Fabien Harambat, Hassan PeerhossainiAbstract:International audienceAerodynamic Cooling Drag, caused by car underhood Cooling, can be reduced by better underhood aerothermal management. This study addresses the aerothermal phenomena encountered in the vehicle underhood compartment by physical analysis of the heat transfer modes in complex internal flows. We report here underhood heat flux and temperature measurements on a vehicle in wind tunnel S4 of Saint-Cyr-France using a new experimental method. The underhood is instrumented by 40 surface and air thermocouples and 20 fluxmeters. Measurements are carried out for three thermal functioning points: the engine in operation and the front wheels positioned on the test facility with power-absorption-controlled rollers. The ultimate aim is to reengineer the underhood architecture so as to reduce the Cooling air flow rate in the underhood component and hence the aerothermal Cooling Drag
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Underhood thermal management: temperature and heat flux measurements and physical analysis
Applied Thermal Engineering, 2009Co-Authors: Mahmoud Khaled, Fabien Harambat, Hassan PeerhossainiAbstract:Aerodynamic Cooling Drag, caused by car underhood Cooling, can be reduced by better underhood aerothermal management. This study addresses the aerothermal phenomena encountered in the vehicle underhood compartment by physical analysis of the heat transfer modes in complex internal flows. We report here underhood heat flux and temperature measurements on a vehicle in wind tunnel S4 of Saint-Cyr-France using a new experimental method. The underhood is instrumented by 40 surface and air thermocouples and 20 fluxmeters. Measurements are carried out for three thermal functioning points: the engine in operation and the front wheels positioned on the test facility with power-absorption-controlled rollers. The ultimate aim is to reengineer the underhood architecture so as to reduce the Cooling air flow rate in the underhood component and hence the aerothermal Cooling Drag.
Mahmoud Khaled - One of the best experts on this subject based on the ideXlab platform.
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Effect of Underhood Architecture on Aerodynamic Drag — Suggestion of New Concepts for Fuel Consumption Reduction
International Journal of Automotive Technology, 2020Co-Authors: Jalal Faraj, Elias Harika, Fabien Harambat, Mohamed Ramadan, Mahmoud KhaledAbstract:The present work concerns an experimental study of the aerodynamic Drag on a simplified vehicle body in relation to the underhood architecture, especially the engine block and Cooling module positions. To proceed, measurements are carried out in wind tunnel for different geometric configurations. The simplified body includes a real Cooling module and a simplified engine block. The measured coefficients concern the aerodynamic Drag, the Cooling Drag and the lift in relation. It was shown that the aerodynamic Drag can be reduced up to 1.4 % when the spacing in the vehicle length between the engine block and Cooling module is well regulated. According to the results obtained, it was noticed that new configurations could reduce the fuel consumption by up to 0.177 L/100 kms.
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Underhood thermal management: Temperature and heat flux measurements and physical analysis
Applied Thermal Engineering, 2010Co-Authors: Mahmoud Khaled, Fabien Harambat, Hassan PeerhossainiAbstract:International audienceAerodynamic Cooling Drag, caused by car underhood Cooling, can be reduced by better underhood aerothermal management. This study addresses the aerothermal phenomena encountered in the vehicle underhood compartment by physical analysis of the heat transfer modes in complex internal flows. We report here underhood heat flux and temperature measurements on a vehicle in wind tunnel S4 of Saint-Cyr-France using a new experimental method. The underhood is instrumented by 40 surface and air thermocouples and 20 fluxmeters. Measurements are carried out for three thermal functioning points: the engine in operation and the front wheels positioned on the test facility with power-absorption-controlled rollers. The ultimate aim is to reengineer the underhood architecture so as to reduce the Cooling air flow rate in the underhood component and hence the aerothermal Cooling Drag
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Aerodynamic Forces on a Simplified Car Body: Towards Innovative Designs for Car Drag Reduction
ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting: Volume 1 Symposia – Parts A B and C, 2010Co-Authors: Mahmoud Khaled, Fabien Harambat, Anthony Yammine, Hassan PeerhossainiAbstract:The present paper exposes the study of the Cooling system circulation effect on the external aerodynamic forces. We report here aerodynamic force measurements carried out on a simplified vehicle model in wind tunnel. Tests are performed for different airflow configurations in order to detect the parameters that can affect the aerodynamic torsor and to confirm others previously suspected, especially the air inlets localization, the air outlet distributions and the underhood geometry. The simplified model has flat and flexible air inlets and several types of air outlet, and includes in its body a real Cooling system and a simplified engine block that can move in the longitudinal and lateral directions. The results of this research are generic and can be applied to any new car design. Results show configurations in which, with respect to the most commonly adopted underhood geometries, the overall Drag coefficient can be decreased by 2%, the aerodynamic Cooling Drag coefficient by more than 50% and the lift coefficient by 5%. Finally, new designs of aerodynamic Drag reduction, based on the combined effects of the different investigated parameters, are proposed.
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Underhood thermal management: temperature and heat flux measurements and physical analysis
Applied Thermal Engineering, 2009Co-Authors: Mahmoud Khaled, Fabien Harambat, Hassan PeerhossainiAbstract:Aerodynamic Cooling Drag, caused by car underhood Cooling, can be reduced by better underhood aerothermal management. This study addresses the aerothermal phenomena encountered in the vehicle underhood compartment by physical analysis of the heat transfer modes in complex internal flows. We report here underhood heat flux and temperature measurements on a vehicle in wind tunnel S4 of Saint-Cyr-France using a new experimental method. The underhood is instrumented by 40 surface and air thermocouples and 20 fluxmeters. Measurements are carried out for three thermal functioning points: the engine in operation and the front wheels positioned on the test facility with power-absorption-controlled rollers. The ultimate aim is to reengineer the underhood architecture so as to reduce the Cooling air flow rate in the underhood component and hence the aerothermal Cooling Drag.
Fabien Harambat - One of the best experts on this subject based on the ideXlab platform.
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Effect of Underhood Architecture on Aerodynamic Drag — Suggestion of New Concepts for Fuel Consumption Reduction
International Journal of Automotive Technology, 2020Co-Authors: Jalal Faraj, Elias Harika, Fabien Harambat, Mohamed Ramadan, Mahmoud KhaledAbstract:The present work concerns an experimental study of the aerodynamic Drag on a simplified vehicle body in relation to the underhood architecture, especially the engine block and Cooling module positions. To proceed, measurements are carried out in wind tunnel for different geometric configurations. The simplified body includes a real Cooling module and a simplified engine block. The measured coefficients concern the aerodynamic Drag, the Cooling Drag and the lift in relation. It was shown that the aerodynamic Drag can be reduced up to 1.4 % when the spacing in the vehicle length between the engine block and Cooling module is well regulated. According to the results obtained, it was noticed that new configurations could reduce the fuel consumption by up to 0.177 L/100 kms.
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Underhood thermal management: Temperature and heat flux measurements and physical analysis
Applied Thermal Engineering, 2010Co-Authors: Mahmoud Khaled, Fabien Harambat, Hassan PeerhossainiAbstract:International audienceAerodynamic Cooling Drag, caused by car underhood Cooling, can be reduced by better underhood aerothermal management. This study addresses the aerothermal phenomena encountered in the vehicle underhood compartment by physical analysis of the heat transfer modes in complex internal flows. We report here underhood heat flux and temperature measurements on a vehicle in wind tunnel S4 of Saint-Cyr-France using a new experimental method. The underhood is instrumented by 40 surface and air thermocouples and 20 fluxmeters. Measurements are carried out for three thermal functioning points: the engine in operation and the front wheels positioned on the test facility with power-absorption-controlled rollers. The ultimate aim is to reengineer the underhood architecture so as to reduce the Cooling air flow rate in the underhood component and hence the aerothermal Cooling Drag
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Aerodynamic Forces on a Simplified Car Body: Towards Innovative Designs for Car Drag Reduction
ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting: Volume 1 Symposia – Parts A B and C, 2010Co-Authors: Mahmoud Khaled, Fabien Harambat, Anthony Yammine, Hassan PeerhossainiAbstract:The present paper exposes the study of the Cooling system circulation effect on the external aerodynamic forces. We report here aerodynamic force measurements carried out on a simplified vehicle model in wind tunnel. Tests are performed for different airflow configurations in order to detect the parameters that can affect the aerodynamic torsor and to confirm others previously suspected, especially the air inlets localization, the air outlet distributions and the underhood geometry. The simplified model has flat and flexible air inlets and several types of air outlet, and includes in its body a real Cooling system and a simplified engine block that can move in the longitudinal and lateral directions. The results of this research are generic and can be applied to any new car design. Results show configurations in which, with respect to the most commonly adopted underhood geometries, the overall Drag coefficient can be decreased by 2%, the aerodynamic Cooling Drag coefficient by more than 50% and the lift coefficient by 5%. Finally, new designs of aerodynamic Drag reduction, based on the combined effects of the different investigated parameters, are proposed.
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Underhood thermal management: temperature and heat flux measurements and physical analysis
Applied Thermal Engineering, 2009Co-Authors: Mahmoud Khaled, Fabien Harambat, Hassan PeerhossainiAbstract:Aerodynamic Cooling Drag, caused by car underhood Cooling, can be reduced by better underhood aerothermal management. This study addresses the aerothermal phenomena encountered in the vehicle underhood compartment by physical analysis of the heat transfer modes in complex internal flows. We report here underhood heat flux and temperature measurements on a vehicle in wind tunnel S4 of Saint-Cyr-France using a new experimental method. The underhood is instrumented by 40 surface and air thermocouples and 20 fluxmeters. Measurements are carried out for three thermal functioning points: the engine in operation and the front wheels positioned on the test facility with power-absorption-controlled rollers. The ultimate aim is to reengineer the underhood architecture so as to reduce the Cooling air flow rate in the underhood component and hence the aerothermal Cooling Drag.
Lennart Löfdahl - One of the best experts on this subject based on the ideXlab platform.
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Aerodynamic Analysis of Cooling Airflow for Different Front-End Designs of a Heavy-Duty Cab-Over-Engine Truck
SAE International Journal of Commercial Vehicles, 2018Co-Authors: Helena Martini, Peter Gullberg, Lennart LöfdahlAbstract:Improving the aerodynamics of heavy trucks is an important consideration in the strive for more energy-efficient vehicles. Cooling Drag is one part of the total aerodynamic resistance acting on a vehicle, which arises as a consequence of air flowing through the grille area, the heat exchangers, and the irregular under-hood area. Today Cooling packages of heavy trucks are dimensioned for a critical Cooling case, typically when the vehicle is driving fully laden, at low speed up a steep hill. However, for long-haul trucks, mostly operating at highway speeds on mostly level roads, it may not be necessary to have all the Cooling airflow from an open-grille configuration. It can therefore be desirable for fuel consumption purposes, to shut off the entire Cooling airflow, or a portion of it, under certain driving conditions dictated by the Cooling demands. In Europe, most trucks operating on the roads are of cab-over-engine type, as a consequence of the length legislations present. However, there are new directions from the European Union, which would permit slightly longer vehicles to improve aerodynamics and also to allow for a safer, more environmentally friendly vehicle. The truck design, where a cab-over-engine cab has an elongated front, is often referred to as a Soft Nose, where, as the name implies, the nose should be “soft” to improve the safety for pedestrians and also for car occupants in the event of a collision. This paper deals with the analysis of Cooling airflow for two different front-end designs of a heavy truck. The first design is a cab-over-engine cab; the second is a Soft Nose cab, which in this case is basically an elongation of the grille area of the cab-over-engine cab to obtain a smoother shape of the cab. The Soft Nose model used in this investigation was extended 200 mm from the cab-over-engine front. Computational Fluid Dynamics was used as the tool for examining the aerodynamic properties of the vehicle models. A steady RANS-based approach was conducted, based on the method evaluated in previous work performed by the authors. The cab-over-engine and Soft Nose models were evaluated in an open-road environment. The configurations were evaluated both with inactive and active heat exchangers, in order to examine the effect of heating the air on the Drag co-efficient and also to determine the Cooling capacity of the different models. A sub- study was performed where different opening percentages of the grille area was investigated to determine the minimum percentage opening that would be needed to achieve a radiator Top Tank Temperature value below a target limit of 100 °C. The results show that there was potential for Drag reductions for the Soft Nose model used. The Cooling airflow was different for the cab-over-engine and Soft Nose models; as a consequence of the longer distance between the grille and Cooling package, less air entered the Cooling module for the Soft Nose model. A large portion of the airflow entering the grille leaked around the Cooling module for the Soft Nose model. Also, following on from the reduced airflow through the Cooling package, the radiator Top Tank Temperature values were considerably increased with the Soft Nose model. It was also shown that for the specific driving condition simulated here, an opening of 17.5% of the grille area was required to ensure sufficient Cooling capacity. An interesting continuation of the Cooling airflow analysis of the Soft Nose model would be to add ducts, guiding the air from the grille to the Cooling module, to investigate if leakage could be reduced and Cooling capacity increased.
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Experimental and numerical investigations of Cooling Drag
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2017Co-Authors: Teddy Hobeika, Simone Sebben, Lennart LöfdahlAbstract:As the target figures for CO2 emissions are reduced every year, vehicle manufacturers seek to exploit all possible gains in the different vehicle attributes. Aerodynamic Drag is an important factor that affects the vehicle’s fuel consumption, and its importance rises with the shift from the New European Driving Cycle to the Worldwide harmonized Light vehicles Test Cycle which has a higher average speed. In order to reduce vehicle Drag, car manufacturers employ the use of grill/spoiler shutters which reduces the amount of air going through the vehicle’s Cooling system, also known as Cooling flow, thus reducing both its Cooling capability and the resultant Cooling Drag. This paper investigates the influence of different grill blockages on the Cooling flow through the radiator of a Volvo S60. By modifying the engine bay and radiator, load cells are used to measure the force acting on the radiator core while the velocity distribution across the radiator core is measured using pressure probes. These values are analyzed and compared to different vehicle configurations and grill inlet designs. A number of test configurations are reproduced in Computational Fluid Dynamics simulations and compared to the test results. For some grill configurations, the simulations provide a good prediction of mass flow and velocity distribution; however a clear discrepancy is present as the grill blockages increase. On the other hand, the force acting on the radiator core was well predicted for all configurations. This paper discusses the different parameters affecting Cooling flow predictions such as wind tunnel blockage and measurement grid discretization by comparing radiator forces and mass flows. In addition, the changes on overall vehicle forces are discussed with the radiator force put in context with Cooling Drag.
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The Aerodynamics of Cooling Air Inlets of Road Vehicles
2009Co-Authors: Lasse Malmkjaer Christoffersen, Lennart LöfdahlAbstract:To reduce carbon dioxide (CO2) emissions of road going vehicles, the aerodynamic Drag is an important area to focus on. Reducing aerodynamic Drag will lead to reduced fuel consumption and hence decreased CO2 emissions. A significant element of the aerodynamic Drag of a modern passenger car is the Cooling Drag, which can constitute up to 15%. Possible solutions to reduce the Cooling Drag include closing off parts of the Cooling air inlets when only a small amount of Cooling air flow is needed. The focus of this study is on the aerodynamic effects closing off the Cooling air inlets have on a modern passenger car. Both full size and scale model experiments were utilized, together with computational fluid dynamic (CFD) simulations. Results show that reduction in aerodynamic Drag is possible by closing off the lower Cooling air inlet and furthermore that this has a noticeable effect on the base pressure. The effect on the base pressure was, however, found to be a little less significant as that caused by completely closing the Cooling air inlets.
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Using CFD in the Design of a Model Scale Radiator
2007Co-Authors: David Söderblom, Lasse Malmkjaer Christoffersen, Lennart LöfdahlAbstract:During the last decade the Drag coefficient of most passenger cars has dropped significantly to values around 0.3 and for certain models even below. A consequence of this is that the so called “Cooling Drag” constitutes a larger portion of the total Drag coefficient, and one key problem in the minimization of the “Cooling Drag” is to optimize the Cooling package. However, the situation is even more complex, since in this Drag minimization model experiments are commonly used and the flow field in the model scale Cooling package will be different as compared to the full scale. This effect must be taken into account in the total optimization process. Hence, the aim of the current work was to develop a realistic radiator geometry to be used in model scale wind tunnel experiments. In this work, the CFD code Fluent was used for studies of the scaling phenomenas by the use of a simplified radiator core geometry. Initial data available for the full size radiator geometry was an empiric expression for the pressure drop over the Cooling package and in the computations the full scale radiator was modelled as a porous media in with its resistance described by an empirical equation. The results from the Fluent computations were used to design a model scale radiator, and to replicate the full scale Cooling package a model radiator was manufactured out of honeycomb, for flow guidance, and fine wire meshes to obtain the relevant pressure drop. The set up was tested in a rig where the designed model was calibrated using different configurations of wire meshes. It was found in the test measurements that the outcome was a fully functional model scale radiator.
Y. L. Cheung - One of the best experts on this subject based on the ideXlab platform.
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Numerical studies on sprinkler-hot layer interaction
International Journal of Modelling and Simulation, 1997Co-Authors: Wan Ki Chow, Y. L. CheungAbstract:This paper describes how sprinkler water spray would interact with a fire-induced hot layer. The field modelling technique is used and the problem is divided into gas and liquid phases. Experimental results reported by Walton and Budnick were used to verify the predicted results. For the gas phase, the set of conservation equations for mass, momentum, and enthalpy is solved numerically using the PISO algorithms. For the liquid phase, the sprinkler water spray is described by a number of droplets with initial velocity and diameter calculated by empirical expressions for the nozzle at different operating water pressures and flowrates. The trajectory of each droplet is calculated by solving the equation of motions, taking into account the Dragging and heat transfer with the hot layer through which it travels. The water droplet is assumed to be non-evaporating, and the convective heat transfer coefficient is fitted by an empirical equation. Only the source terms at the gas momentum and enthalpy equations included the interaction effects with water droplets, that is, the Particle-Source-In-Cell method. The predicted results include the gas flow, temperature, and smoke concentration field; the shape of the water spray; and some relevant macroscopic parameters such as amount of convective Cooling, Drag to buoyancy ratio, and so on. Effect of the mean droplet size on those parameters is illustrated in this paper.
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Simulation of sprinkler-hot layer interaction using a field model
Fire and Materials, 1994Co-Authors: Wan Ki Chow, Y. L. CheungAbstract:This paper reports a study of the interaction of a sprinkler water spray with the fire-induced hot layer using the field modelling technique. Data obtained in the large test room of the recent Swedish experiments reported by Ingason and Olsson (1992) are used to validate the results. The problem is divided into a gas phase and a liquid phase. For the gas phase, the set of conservation equations for mass, momentum and enthalpy of air flow induced by the fire is solved numerically using the Pressure Implicit Splitting Operator (PISO) algorithm. For the liquid phase, the sprinkler water spray is described by a number of droplets with initial velocity and diameter calculated by empirical expressions for the nozzle at different operating water pressures and flow rates. The trajectory of each droplet is calculated by solving the equation of motions, by including the Dragging and heat transfer with the hot layer. The water droplet is assumed to be non-evaporating and only the source terms in the gas momentum and enthalpy equations of the air flow included the interaction effects with water droplets, i.e. the ‘Particle-Source-in-Cell’ method. The predicted results include the gas flow, temperature and smoke concentration field; the shape of the water spray; and some relevant macroscopic parameters such as amount of convective Cooling, Drag-to-buoyancy ratio, etc. The average smoke layer temperature and the smoke layer interface height are also calculated. The effect of the mean droplet size on those parameters is illustrated. Finally, a comparison of the water density received at floor level in cases with and without the fire is made.