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2017-06-05
Technical Paper
2017-01-1834
Dirk von Werne, Prasanna Chaduvula, Patrick Stahl, Michael Jordan, Jamison Huber, Korcan Kucukcoskun, Mircea Niculescu
Fan noise can form a significant part of the vehicle noise signature and needs hence to be optimized in view of exterior noise and operator exposure. Putting together unsteady CFD simulation with acoustic FEM modeling, tonal and broadband fan noise can be accurately predicted, accounting for the sound propagation through engine compartment and vehicle frame structure. This paper focuses on method development and validation in view of the practical vehicle design process. In a step by-step approach, the model has been validated against a dedicated test-set-up, so that good accuracy of operational fan noise prediction could be achieved. Main focus was on the acoustic transfer through the engine compartment. The equivalent acoustic transfer through radiators/heat exchangers is modeled based on separate detailed acoustic models. The updating process revealed the sensitivity of various components in the engine compartment.
2017-04-11
Journal Article
2017-01-9450
Ali Reza Taherkhani, Carl Gilkeson PhD, Philip Gaskell PhD, Rob Hewson PhD, Vassili Toropov PhD, Amin Rezaienia PhD, Harvey Thompson
Abstract This paper investigates the optimization of the aerodynamic design of a police car, BMW 5-series which is popular police force across the UK. A Bezier curve fitting approach is proposed as a tool to improve the existing design of the warning light cluster in order to reduce drag. A formal optimization technique based on Computational Fluid Dynamics (CFD) and moving least squares (MLS) is used to determine the control points for the approximated curve to cover the light-bar and streamline the shape of the roof. The results clearly show that improving the aerodynamic design of the roofs will offer an important opportunity for reducing the fuel consumption and emissions for police vehicles. The optimized police car has 30% less drag than the non-optimized counter-part.
2017-03-28
Technical Paper
2017-01-1281
Rajesh Kumar, Olivier Laget, Guillaume Pilla, Guillaume Bourhis, Roland Dauphin, Loic de Francqueville, Jean-Pascal Solari
Abstract Reduction of CO2 emissions is becoming one of the great challenges for future gasoline engines. The aim of the current research program (OOD: Octane On Demand) is to use the octane number as a tuning parameter to simultaneously make the engine more efficient and reduce CO2 emissions. The idea is to prevent knock occurrence by adapting the fuel RON injected in the combustion chamber. Thus, the engine cycle efficiency is increased by keeping combustion phasing at its optimum. This is achieved by a dual fuel injection strategy, involving a low-RON base fuel (Naphtha or Low RON cost effective fuel) and a high-RON octane booster (ethanol). The ratio of fuel quantity on each injector is adapted at each engine cycle to fit the RON requirement as a function of engine operating conditions. A first part of the project, described in [18], was dedicated to the understanding of mixture preparation resulting from different dual-fuel injection strategies.
2017-03-28
Technical Paper
2017-01-1292
Saiful Bari, Idris Saad
Abstract Diesel engine can be run with biodiesel which has the potential to supplement the receding supply of crude oil. As biodiesel possess similar physiochemical properties to diesel, most diesel engines can run with biodiesel with minimum modifications. However, the viscosity of biodiesel is higher, and the calorific value is lower than diesel. Therefore, when biodiesel is used in diesel engines, it is usually blended with diesel at different proportions. Use of 100% biodiesel in diesel engines shows inferior performance of having lower power and torque. Improving in-cylinder airflow characteristic to break down higher viscous biodiesel and to improve air-fuel mixing are the aims of this research. Therefore, guide vanes in the intake runner were used in this research to improve the performance of diesel engine run with biodiesel.
2017-03-28
Technical Paper
2017-01-1460
Nitesh Jadhav, Linda Zhao, Senthilkumar Mahadevan, Bill Sherwood, Krishnakanth Aekbote, Dilip Bhalsod
Abstract The Pelvis-Thorax Side Air Bag (PTSAB) is a typical restraint countermeasure offered for protection of occupants in the vehicle during side impact tests. Currently, the dynamic performance of PTSAB for occupant injury assessment in side impact is limited to full-vehicle evaluation and sled testing, with limited capability in computer aided engineering (CAE). The widely used CAE method for PTSAB is a flat bag with uniform pressure. The flat PTSAB model with uniform pressure has limitations because of its inability to capture airbag deployment during gap closure which results in reduced accuracy while predicting occupant responses. Hence there is a need to develop CAE capability to enhance the accuracy of prediction of occupant responses to meet performance targets in regulatory and public domain side impact tests. This paper describes a new CAE methodology for assessment of PTSAB in side impact.
2017-03-28
Technical Paper
2017-01-1444
Mitali Chakrabarti, Alfredo Perez Montiel, Israel Corrilo, Jing He, Angelo Patti, James Gebbie, Loren Lohmeyer, Bernd Dienhart, Klaus Schuermanns
CO2 is an alternative to replace the conventional refrigerant (R134a) for the air-conditioning system, due to the high Global Warming Potential (GWP) of R134a. There are concerns with the use of CO2 as a refrigerant due to health risks associated with exposure to CO2, if the concentration of CO2 is over the acceptable threshold. For applications with CO2 as the refrigerant, the risk of CO2 exposure is increased due to the possibility of CO2 leakage into the cabin through the duct system; this CO2 is in addition to the CO2 generated from the respiration of the occupants. The initiation of the leak could be due to a crash event or a malfunction of the refrigerant system. In an automobile, where the interior cabin is a closed volume (with minimal venting), the increase in concentration can be detrimental to the customer but is hard to detect.
2017-03-28
Technical Paper
2017-01-1335
Jie Chen, Guangqiang Wu
Abstract Jet-wake flow and secondary flows are undesirable in torque converters as they are responsible for flow losses and flow nonuniformity; that is, jet-wake flow and secondary flows negatively affect the torque converter performance. Therefore, it is very important to investigate and minimize the undesirable flows to decrease flow losses in torque converter. However, the existing studies are limited to employ geometry design parameter modifications rather than focusing on the actual causes and intrinsic physical mechanism that generate the flows to reduce the flow losses. In this paper, Calculation model of a torque converter is presented first and a three dimensional CFD code was used to simulate the internal flow field of a torque converter. The simulation results coincide with experimental measurements, which verifies the validity of the method. Based on flow field calculation results, the internal flow field of impeller, turbine and stator were analyzed, respectively.
2017-03-28
Technical Paper
2017-01-1537
Ananya Bhardwaj
Abstract Improving brake cooling has commanded substantial research in the automotive sector, as safety remains paramount in vehicles of which brakes are a crucial component. To prevent problems like brake fade and brake judder, heat dissipation should be maximized from the brakes to limit increasing temperatures. This research is a CFD investigation into the impact of existing wheel center designs on brake cooling through increased cross flow through the wheel. The new study brings together the complete wheel and disc geometries in a single CFD study and directly measures the effect on brake cooling, by implementing more accurately modeled boundary conditions like moving ground to replicate real conditions correctly. It also quantifies the improvement in the cooling rate of the brake disc with a change in wheel design, unlike previous studies.
2017-03-28
Technical Paper
2017-01-1321
Meisam Mehravaran, Yi Zhang
Abstract Degas bottles have been extensively used in vehicles in order to act as an air pillow on top of the cooling loop and provide space for expansion. One of the important characteristics of the bottle which defines if it will work in a certain loop is the so called “capacity” of the bottle which defines the flowrate that degas bottle would be able to pass through without any foaming. Considering the complex geometry of degas bottle and the foaming phenomena, predicting the behavior of coolant in the bottle passages is challenging which requires costly tests. Computational Fluid Dynamics (CFD) has been extensively used in simulating multi-phase flows in automotive components. In the current project, CFD has been used to simulate the behavior of flow in bottle chambers and to provide guidelines for the design team in order to increase the bottle performance/capacity. The CFD guidelines were in agreement with test results and lead to improving the degas bottle capacity.
2017-03-28
Technical Paper
2017-01-1320
Yucheng Liu
Abstract A cost effective, portable particulate management system was developed, prototyped, and evaluated for further application and commercialization, which could remove and dispose particulate matter suspended in air efficiently and safely. A prototype of the present system was built for experimental assessment and validation. The experimental data showed that the developed particulate management system can effectively clean the air by capturing the particles inside it. Effects of viscosity of filter medium on the performance of the developed system were also discussed. The present system is very flexible, whose size and shape can be scaled and changed to be fit for different applications. Its manufacturing cost is less than $10. Based on the experimental validation results, it was found that the present system can be further developed, commercialized, and applied for a variety of industries.
2017-03-28
Technical Paper
2017-01-0779
Wolfgang Friedrich, Roman Grzeszik, Philipp Lauschke, Vadim Zelenov, Michael Wensing
Abstract A previous study by the authors has shown an efficiency benefit of up to Δηi = 10 % for stratified operation of a high pressure natural gas direct injection (DI) spark ignition (SI) engine compared to the homogeneous stoichiometric operation with port fuel injection (PFI). While best efficiencies appeared at extremely lean operation at λ = 3.2, minimum HC emissions were found at λ = 2. The increasing HC emissions and narrow ignition time frames in the extremely lean stratified operation have given the need for a detailed analysis. To further investigate the mixture formation and flame propagation und these conditions, an optically accessible single-cylinder engine was used. The mixture formation and the flame luminosity have been investigated in two perpendicular planes inside the combustion chamber.
2017-03-28
Technical Paper
2017-01-0860
PengBo Dong, Jun Yamauchi, Keiya Nishida, Youichi Ogata
Abstract With the aim of improving engine performance, recent trend of fuel injection nozzle design followed by engineers and researchers is focusing on more efficient fuel break up, atomization, and fuel evaporation. Therefore, it is crucial to characterize the effect of nozzle geometric design on fuel internal flow dynamics and the consequent fuel-air mixture properties. In this study, the internal flow and spray characteristics generated by the practical multi-hole (10 holes) nozzles with different nozzle hole length and hole diameter were investigated in conjunction with a series of computational and experimental methods. Specifically, the Computational Fluid Dynamics (CFD) commercial code was used to predict the internal flow variation inside different nozzle configurations, and the high-speed video observation method was applied to visualize the spray evolution processes under non-evaporating conditions.
2017-03-28
Technical Paper
2017-01-0582
Naoki Kurimoto, Naoki Watanabe, Shinya Hoshi, Satoru Sasaki, Masashi Matsumoto
Abstract A methodology for simulating effect of international variations in fuel compositions on spray combustion is proposed. The methodology is validated with spray combustion experiments with real fuels from three different countries. The compositions of those fuels were analyzed through GC×GC and H-NMR. It was found that ignition delay times, flame region and flame luminosity were significantly affected by the compositional variations. For the simulation, an evaporation surrogate consisting of twenty two species, covering basic molecular types and a wide range of carbon numbers, is developed. Each species in the evaporation surrogate is then virtually converted to a reaction surrogate consisting of n-hexadecane, methylcyclohexane and 1,2,4-trimethyl benzene so that combustion reactions can be calculated with a published kinetic model. The virtual species conversion (VSC) is made so as to take over combustion-related properties of each species of evaporation surrogates.
2017-03-28
Technical Paper
2017-01-0135
Jose Grande, Julio Abraham Carrera, Manuel Dieguez Sr
Abstract Exhaust Gas Recirculation (EGR) is an effective technique for reducing NOx emissions in order to achieve the ever more stringent emissions standards. This system is widely used in commercial vehicle engines in which thermal loads and durability are a critical issue. In addition, the development deadlines of the new engine generations are being considerably reduced, especially for validation test phase in which customers usually require robust parts for engine validation in the first stages of the project. Some of the most critical issues in this initial phases of program development are heavy boiling and thermal fatigue. Consequently it has been necessary to develop a procedure for designing EGR coolers that are sufficiently robust against heavy boiling and thermal fatigue in a short period of time, even when the engine calibration is not finished and the working conditions of the EGR system are not completely defined.
2017-03-28
Technical Paper
2017-01-0138
Chris Lim, Peter Ireland, Nicholas Collett
Abstract The analysis of thermal fields in the underhood region is complicated by the complex geometry and the influence of a multitude of different heat sources. This complexity means that running full CFD analyses to predict the thermal field in this region is both computationally expensive and time consuming. A method of predicting the thermal field using linear superposition has been developed in order to analyse the underhood region of a simplified Formula One race car, though the technique is applicable to all vehicles. The use of linear superposition allows accurate predictions of the thermal field within a complex geometry for varying boundary conditions with negligible computational costs once the initial characterisation CFD has been run. A quarter scale, rear end model of a Formula One race car with a simplified internal assembly is considered for analysis, though the technique can also be applied to commercial and industrial vehicles.
2017-03-28
Technical Paper
2017-01-0143
Neelakandan Kandasamy, Steve Whelan
Abstract During cabin warm-up, effective air distribution by vehicle climate control systems plays a vital role. For adequate visibility to the driver, major portion of the air is required to be delivered through the defrost center ducts to clear the windshield. HVAC unit deliver hot air with help of cabin heater and PTC heater. When hot air interacts with cold windshield it causes thermal losses, and windshield act as sink. This process may causes in delay of cabin warming during consecutive cabin warming process. Thus it becomes essential to predict the effect of different windscreen defrost characteristics. In this paper, sensitivity analysis is carried for different windscreen defrosts characteristics like ambient conditions, modes of operation; change in material properties along with occupant thermal comfort is predicted. An integrated 1D/3D CFD approach is proposed to evaluate these conditions.
2017-03-28
Technical Paper
2017-01-0142
Chunhui Zhang, Mesbah Uddin, Lee Foster
Abstract The demand for better fuel economy pushed by both consumer and Environmental Protection Agency (EPA), made OEMs to put more effort on other areas beside vehicle external aerodynamics. As one of these areas, under-hood aero-thermal management has taken an important role in the new road vehicle design process, due to the combination of growing engine power demands, utilization of sophisticated under-hood and underbody devices, and emission regulations. The challenge of the under-hood aerothermal management is not only due to the complexity of under-hood compartment, but also as a result of the complex heat transfer phenomena involving conduction, convention and thermal radiation. In this study, 3D CFD simulations were used to investigate the under-hood aerothermal flow features. The full vehicle model with detailed under-hood components used in this study is a Hyundai Veloster. A commercial CDF code Star-CCM+ version 11.04 from CD-adapco was used to run all the simulations.
2017-03-28
Technical Paper
2017-01-0613
James R. MacDonald, Claudia M. Fajardo, Mark Greene, David Reuss, Volker Sick
Abstract Developing a complete understanding of the structure and behavior of the near-wall region (NWR) in reciprocating, internal combustion (IC) engines and of its interaction with the core flow is needed to support the implementation of advanced combustion and engine operation strategies, as well as predictive computational models. The NWR in IC engines is fundamentally different from the canonical steady-state turbulent boundary layers (BL), whose structure, similarity and dynamics have been thoroughly documented in the technical literature. Motivated by this need, this paper presents results from the analysis of two-component velocity data measured with particle image velocimetry near the head of a single-cylinder, optical engine. The interaction between the NWR and the core flow was quantified via statistical moments and two-point velocity correlations, determined at multiple distances from the wall and piston positions.
2017-03-28
Technical Paper
2017-01-0612
Li Shen, Kwee-Yan Teh, Penghui Ge, Yusheng Wang, David L.S. Hung
Abstract Proper Orthogonal Decomposition (POD) is a useful statistical tool for analyzing the cycle-to-cycle variation of internal combustion engine in-cylinder flow field. Given a set of flow fields (also known as snapshots) recorded over multiple engine cycles, the POD analysis optimally decomposes the snapshots into a series of flow patterns (known as POD modes) and corresponding coefficients of successively maximum flow kinetic energy content. These POD results are therefore strongly dependent on the kinetic energy content of the individual snapshots, which may vary over a wide range. However, there is as yet no algorithm in the literature to define, detect, and then remove outlier snapshots from the dataset in a systematic manner to ensure reliable POD results.
2017-03-28
Technical Paper
2017-01-0615
Penghui Ge, Fengnian Zhao, David Hung, Hujie Pan, Min Xu
Abstract Combustion efficiency of internal combustion engine is closely influenced by the air flow pattern in the engine cylinder. Some researchers use high-speed particle image velocimetry to visualize and measure the temporally and spatially resolved in-cylinder velocity flow fields in the optically assessable engine. However, the transparent cylindrical liner makes it difficult to accurately determine the particle displacements inside the cylinder due to the optically distorted path of scattering light from seeding particles through the curved liner. To correct for the distortion-induced error in the seeding particle positions through the optical liner, the distortion mapping function is modeled using the Gaussian optics theory. Two artificial flow patterns with 5 by 5 vectors were made to illustrate the mapping correction. Distortion-induced error of velocity vectors was precisely mapped in six different planes inside the cylinder.
2017-03-28
Technical Paper
2017-01-0558
Lei Cui, Tianyou Wang, Kai Sun, Zhen Lu, Zhizhao Che, Yanzhe Sun
Abstract The scavenging process in two-stroke marine engines not only transports burnt gas out of the cylinder but also provides fresh air for the next cycle, thereby significantly affecting the engine performance. In order to enhance fuel-air mixing, the scavenging process usually generates swirling flow in uniflow-type scavenging engines. The scavenging stability directly determines the scavenging efficiency and even influences fuel-air mixing, combustion, and emission of the engine. In the present study, a computational fluid dynamics (CFD) analysis of the scavenging process in a steady-state scavenging flow test is conducted. A precession phenomenon is found in the high swirl model, and Proper Orthogonal Decomposition (POD) method is used to analyze the reason and the multi-scale characteristics of the precession phenomenon.
2017-03-28
Technical Paper
2017-01-0554
Yu Li, Hongsheng Guo, Hailin Li
Abstract Computational fluid dynamics (CFD) model has been widely applied in internal combustion (IC) engine research. The integration of chemical kinetic model with CFD provides an opportunity for researchers to investigate the detailed chemical reactions for better understanding the combustion process of IC engines. However, the simulation using CFD has generally focused on the examination of primary parameters, such as temperature and species distributions. The detailed investigation on chemical reactions is limited. This paper presents the development of a post-processing tool capable of calculating the rate of production (ROP) of interested species with the known temperature, pressure, and concentration of each species in each cell simulated using CONVERGE-SAGE CFD model.
2017-03-28
Technical Paper
2017-01-0557
Masumeh Gholamisheeri, Bryce Thelen, Elisa Toulson
Abstract Three dimensional numerical simulation of the transient turbulent jet and ignition processes of a premixed methane-air mixture of a turbulent jet ignition (TJI) system is performed using Converge computational software. The prechamber initiated combustion enhancement technique that is utilized in a TJI system enables low temperature combustion by increasing the flame propagation rate and therefore decreasing the burn duration. Two important components of the TJI system are the prechamber where the spark plug and injectors are located and the nozzle which connects the prechamber to the main chamber. In order to model the turbulent jet of the TJI system, RANS k-ε and LES turbulent models and the SAGE chemistry solver with a reduced mechanism for methane are used.
2017-03-28
Technical Paper
2017-01-0567
Andrea Twellmeyer, Fabian Kopple, Bernhard Weigand
Abstract Compressed Natural Gas (CNG) is a promising alternative fuel for internal combustion engines as its combustion is fuel-efficient and lean in carbon dioxide compared to gasoline. The high octane number of methane gives rise to significant increase of the thermodynamic efficiency due to higher possible compression ratios. In order to use this potential, new stratified mixture formation concepts for CNG are investigated by means of numerical fluid simulations. For decades RANS methods have been the industry standard to model three-dimensional flows. Indeed, there are well-known deficiencies of the widely used eddy viscosity turbulence models based on the applied Boussinesq hypothesis. Reynolds stress turbulence models as well as scale resolving simulation approaches can be appealing alternative choices since they offer higher accuracy. However, due to their large computing effort, they are still mostly impractical for the daily use in industrial product development processes.
2017-03-28
Technical Paper
2017-01-0529
Seamus Kane, Xuesong Li, Benjamin Wolk, Isaac Ekoto, William F. Northrop
Abstract Fuel reforming during a Negative Valve Overlap (NVO) period is an effective approach to control Low Temperature Gasoline Combustion (LTGC) ignition. Previous work has shown through experiments that primary reference fuels reform easily and produce several species that drastically affect ignition characteristics. However, our previous research has been unable to accurately predict measured reformate composition at the end of the NVO period using simple single-zone models. In this work, we use a stochastic reactor model (SRM) closed cycle engine simulation to predict reformate composition accounting for in-cylinder temperature and mixture stratification. The SRM model is less computationally intensive than CFD simulations while still allowing the use of large chemical mechanisms to predict intermediate species formation rates.
2017-03-28
Technical Paper
2017-01-0847
Ming Ge, Xingyu Liang, Hanzhengnan Yu, Yuesen Wang, Hongsheng Zhang
Abstract Spray impacting on a lube oil film with a finite thickness is a common phenomenon in IC engines and plays a critical role in the fuel-air mixture process and combustion. With the use of early injection strategy to achieve HCCI combustion mode in diesel engines, this phenomenon becomes more and more prominent. In addition, oxygenated fuels such as methanol and ethanol are regarded as alternative fuel and additives to improve the overall performance of HCCI engine. Therefore, a better understanding about the role of lube oil film thickness in methanol-diesel and ethanol-diesel blended fuels spray/wall impingement is helpful for accumulating experimental data to establish a more accurate spray/wall impingement model and optimize the combustion in HCCI engines. In this paper, the effect of lube oil film thickness on the characteristics of spray/wall impingement of different fuels are investigated in a constant volume bomb test system.
2017-03-28
Technical Paper
2017-01-0846
Raul Payri, Gabriela Bracho, Pedro Marti-Aldaravi, Alberto Viera
In the present work a constant-pressure flow facility able to reach 15 MPa ambient pressure and 1000 K ambient temperature has been employed to carry out experimental studies of the combustion process at Diesel engine like conditions. The objective is to study the effect of orifice diameter on combustion parameters as lift-off length, ignition delay and flame penetration, assessing if the processing methodologies used for a reference nozzle are suitable in heavy duty applications. Accordingly, three orifice diameter were studied: a spray B nozzle, with a nominal diameter of 90 μm, and two heavy duty application nozzles (diameter of 194 μm and 228 μm respectively). Results showed that nozzle size has a substantial impact on the ignition event, affecting the premixed phase of the combustion and the ignition location.
2017-03-28
Technical Paper
2017-01-0845
Kazufumi Serizawa, Daiji Ueda, Naoki Mikami, Yasufumi Tomida, Jost Weber
Abstract The Diesel engine performance was drastically improved since the introduction of the Common Rail system in 1996. Over the years, the Common Rail technology was continuously improved to reduce the fuel consumption, engine-out emissions and enhance the drivability. However further technical improvement steps for a precise control of combustion are required to satisfy the increasing stringent worldwide emissions limits and to contribute to attractively performing Diesel powered vehicles. Common Rail injectors significantly contribute to improve the combustion. This improvement can be achieved by precisely controlling the injected fuel quantity and increasing the injection pressure. In addition to those features, a more rectangular injection rate, the capability of stable multiple injections at shorter intervals and the control of the spray shape, are required to achieve an optimized fuel mixture.
2017-03-28
Technical Paper
2017-01-0842
Luis Bravo, Scott Ripplinger, Omid Samimi
Abstract Numerical simulations of diesel reacting jets in a simulated engine environment were carried out to study the effect of oxygen concentration on the ignition delay time and lift-off length dynamics. A recently developed mechanism, direct integration of chemistry, and well established Lagrangian-Eulerian spray model were utilized for 3-D turbulent spray combustion simulation under engine like conditions. The simulations are able to provide a time-history of chemical species including formaldehyde CH2O intermediates and hydroxide OH radicals to facilitate development of auto-ignition and lift off length numerical diagnostics. A range of important operating points including variations in the oxygen concentration, rail pressure, and injection duration were examined. The purpose of conducting the parametric studies is to investigate the consistency of the results and provide a more comprehensive analysis than a single point condition.
2017-03-28
Technical Paper
2017-01-0856
Yanzhi Zhang, Ming Jia, Huiquan Duan, Pengfei Wang, Jianxiang Wang, Hong Liu, MaoZhao Xie
Abstract The phenomenon of a thin liquid film separation and atomization at expanding corners during the spray/wall interaction is usually encountered in premixed charge compression ignition (PCCI) engines. However, detailed information about the film separation is very limited, especially under high injection pressure conditions. In this study, experimental study was conducted to investigate the effects of injection pressure and impingement distance on the evolutions of the impinging spray and the adhered film at simplified geometries with an expanding corner by employing a high-speed camera. In addition, an improved hybrid film separation and atomization model was developed, which includes the sub-models of film separation criterion, film separation mass ratio, and the film atomization model based on the Rayleigh-Taylor instability theory.
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