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Viewing 1 to 30 of 11469
2018-01-16
Event
2017-09-19
Event
2017-09-16
Journal Article
2017-01-9180
Johannes Wurm, Eetu Hurtig, Esa Väisänen, Joonas Mähönen, Christoph Hochenauer
Abstract The presented paper focuses on the computation of heat transfer related to continuously variable transmissions (CVTs). High temperatures are critical for the highly loaded rubber belts and reduce their lifetime significantly. Hence, a sufficient cooling system is inevitable. A numerical tool which is capable of predicting surface heat transfer and maximum temperatures is of high importance for concept design studies. Computational Fluid Dynamics (CFD) is a suitable method to carry out this task. In this work, a time efficient and accurate simulation strategy is developed to model the complexity of a CVT. The validity of the technique used is underlined by field measurements. Tests have been carried out on a snowmobile CVT, where component temperatures, air temperatures in the CVT vicinity and engine data have been monitored. A corresponding CAD model has been created and the boundary conditions were set according to the testing conditions.
2017-09-04
Technical Paper
2017-24-0161
Noboru Uchida, Hideaki Osada
It can’t be avoided reducing heat loss from in-cylinder wall for further improvement in brake thermal efficiency (BTE). Especially for diesel engines, spray flame interference on the cavity and piston top wall during combustion period could be a major cause of the heat loss. To reduce heat transfer between hot gas and cavity wall, thin Zirconia layer (0.5mm) on the cavity surface of the forged steel piston was firstly formed by thermal spray coating aiming higher surface temperature swing precisely synchronized with flame temperature near the wall resulting in the reduction of temperature difference. However, no apparent difference in the heat loss was observed. On the contrary, BTE was deteriorated by the increase in other energy losses. To find out the reason why heat loss was not so improved, direct observation of flame impingement to the cavity wall was carried out with the top view visualization technique, for which one of the exhaust valves was modified to a sapphire window.
2017-09-04
Technical Paper
2017-24-0158
Teresa Castiglione, Giuseppe Franzè, Angelo Algieri, Pietropaolo Morrone, Sergio Bova
The paper shows how specific requirements of the cooling system of an ICE can be met by actuating the coolant flow rate independently of engine speed, by means of an electric pump and of an ad-hoc developed control system. Given that the proposed methodology is valid for each condition, in the present paper the focus is on the engine operating under fully warmed conditions, with the aim to keep the wall temperature into the prescribed limits, with the lowest possible coolant flow rates. This goal is achieved by properly defining the controller parameters. The developed controller is based on the Robust Model Predictive Control approach, which makes use of a lumped parameter model of the engine cooling system. The model also includes the radiator-thermostatic valve-fan block and incorporates the nucleate boiling heat transfer regime.
2017-09-04
Technical Paper
2017-24-0107
Alessandro Montanaro, Luigi Allocca, Vittorio Rocco, Michela Costa, Daniele Piazzullo
Enhancement of i.c. engine performances in terms of fuel economy and environment and human health preservation is an increasing key factor of the research in recent times. Mainly, that is due to the more and more stringent European and worldwide regulations tending to limit pollutant emissions to carbon monoxide, unburned hydrocarbons, nitrogen oxide, and particulate matter. Development of direct injection strategy (DI) in spark ignition (SI) engines partially fulfilled these tasks, as they run at higher compression ratios, with respect to port fuel injection (PFI), and operating with different injection strategies, so a greatest control over the air-to-fuel ratio is achieved. However, today the engines’ complexity and the number of sub-systems have increased, so the traditional techniques used for their optimization are often inadequate for the required challenges of high power output and low environmental impact.
2017-09-04
Technical Paper
2017-24-0076
Mark A. Hoffman, Ryan O'Donnell, Zoran Filipi
The proven impact of combustion chamber deposits on advanced compression ignition combustion strategies has steered recent works toward the development of thermal barrier coatings, which can mimic their benefits on combustion efficiency and operational range expansion. However, recent work based on statistical thermodynamics has indicated that inter-molecular radiation during the combustion event may subject the combustion chamber walls to non-negligible radiation heat transfer, regardless of the relatively low soot formation within the well-mixed and lean charge. In the present paper, the impact of radiation heat transfer on combustion chamber deposits and thermal barrier coatings is studied. The morphological construction of the combustion chamber deposit layer is shown to be partially transparent to radiation heat transfer, drawing corollaries with ceramic based thermal barrier coatings.
2017-09-04
Technical Paper
2017-24-0041
Daniele Piazzullo, Michela Costa, Luigi Allocca, Alessandro Montanaro, Vittorio ROCCO
In gasoline direct injection (GDI) engines, dynamics of the possible spray-wall interaction are key factors affecting the air-fuel mixture distribution and equivalence ratio at spark timing, hence influencing the development of combustion and the pollutants formation at the exhaust. Gasoline droplets impact may rebound with consequent secondary atomization or deposit in the liquid phase over walls as a wallfilm. This last slowly evaporate with respect to free droplets, leading to local enrichment of the mixture, hence to increased unburned hydrocarbons and particulate matter emissions. In this scenario, complex phenomena characterize the turbulent multi-phase system where heat transfer involves the gaseous mixture (made of air and gasoline vapour), the liquid phase (droplets not yet evaporated and wallfilm) and the solid wall, especially in the so-called wall-guided mixture formation mode.
2017-09-04
Technical Paper
2017-24-0032
Gilles Decan, Stijn Broekaert, Tommaso Lucchini, Gianluca D'Errico, Jan Vierendeels, Sebastian Verhelst
The present work details a study of the heat flux through the walls of an internal combustion engine. The determination of this heat flux is an important aspect in engine optimization, as it influences the power, efficiency and the emissions of the engine. Therefore, a set of simulation tools in the OpenFOAM® software has been developed, that allows the calculation of the heat transfer through engine walls for ICEs. Normal practice in these types of engine simulations is to apply a wall function model to calculate the heat flux, rather than resolving the complete thermo-viscous boundary layer, and perform simulations of the closed engine cycle. When dealing with a complex engine, this methodology will reduce the overall computational cost. It however increases the need to rely on assumptions on both the initial flow field and the behavior in the near-wall region.
2017-09-04
Technical Paper
2017-24-0021
Sabino Caputo, Federico Millo, Giancarlo Cifali, Francesco Concetto Pesce
One of the key technologies for the improvement of the diesel engine thermal efficiency is the reduction of the engine heat transfer through the thermal insulation of the combustion chamber. This paper presents a numerical investigation on the effects of the combustion chamber insulation on the heat transfer, thermal efficiency and exhaust temperatures of a 1.6 l passenger car, turbo-charged diesel engine. First, the complete insulation of the engine components, like pistons, liner, firedeck and valves, has been simulated. This analysis has showed that the piston is the component with the greatest potential for the in-cylinder heat transfer reduction (ideally up to 46 %) and for Brake Specific Fuel Consumption (BSFC) reduction (up to 9 %), while firedeck, liner and valves only contribute respectively to 23 %, 19 % and 15 % in heat transfer decrease.
2017-09-04
Technical Paper
2017-24-0016
Morris Langwiesner, Christian Krueger, Sebastian Donath, Michael Bargende
Aiming on the evaluation of SI-engines with extended expansion cycle realized over the crank drive, engine process simulation is an important tool to predict the engine efficiency. One challenge is to consider concept specific effects as best as possible by using appropriate submodels. Particularly the choice of a suitable heat transfer model is crucial due to the significant change in cranktrain kinematics. The usage of the mean piston speed to calculate a heat-transfer-relevant velocity is not sufficient. The heat transfer model according to Bargende combines for its calculation the current piston speed with a simplified k-ε-model. In this paper the eligibility of this model for engines with extended expansion is assessed. Therefore a single-cylinder engine is equipped with fast-response surface-thermocouples in the cylinder head. The surface heat flux is calculated by solving the unsteady heat conduction equation.
2017-07-10
Technical Paper
2017-28-1951
K Nantha Gopal, B. Ashok, Rishabh Bahuguna, Tanmay Prasad
Abstract Thermal management is one of the most challenging and innovative aspects of the automotive industry. The efficiency of the vehicle cooling framework unequivocally relies upon the air stream through the radiator core. Significant advances in thermal management are being embraced in the field of radiator material and coolant. The radiator shouldn't be exclusively credited for the reliable cooling of the engine. There are other auto parts that play an essential role in keeping engine temperature at a manageable level. The fan-shroud assembly is an important component of the cooling system. While the fan is responsible for drawing in air, the fan shroud's job is to ensure uniform air distribution to the radiator core. By assisting airflow in the engine compartment the fan shroud helps in dismissing excess heat from the engine. This assembly also prevents the recirculation of heated air through the cooling fan.
2017-07-10
Technical Paper
2017-28-1958
Jyothivel Giridharan, Gokul Kumar
Bio-fuels potentially represent a more environmentally friendly alternative to fossil fuels as they produce fewer greenhouse gas emissions when burned. Ethanol is one such bio-fuel alternative to the conventional fossil fuels. Towards the initiative of sustainable transportation using alternative fuels, it is attempted to develop an ethanol powered engine for commercial vehicles and this paper attempts to explain the 1D thermodynamic simulation carried out for predicting the engine performance and combustion characteristics, as a part of the engine development program. Engine simulation is becoming an increasingly important engineering tool for reducing the development cost and time and also helps in carrying out various DOE iterations which are rather difficult to be conducted experimentally in any internal combustion engine development program. AVL Boost software is used for modeling and simulation.
Viewing 1 to 30 of 11469

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