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Viewing 1 to 30 of 2334
2016-05-18 ...
  • May 18-20, 2016 (8:30 a.m. - 4:30 p.m.) - Troy, Michigan
Training / Education Classroom Seminars
Fuel composition has had to change with the advent of more stringent emission regulations. Reformulated gasoline (RFG), for example, is vastly different from gasoline of even ten years ago. Tightening regulations on diesel emissions will dramatically change both diesel fuel and engine design. This three-day seminar will review the fundamentals of motor fuels, combustion and motor power generation. The primary content of the course provides a basic introduction to the technology, performance, evaluation, and specifications of current gasoline, diesel, and turbine fuels.
2016-04-05
Technical Paper
2016-01-0699
Jacob McKenzie, Wai K. Cheng
An ignition delay correlation encompassing the effects of temperature, pressure, residual gas, EGR, and lambda (on both the rich and lean sides) has been developed. The procedure uses the individual knocking cycle data from a boosted direct injection SI engine (GM LNF) operating at 1250 to 2000 rpm, 8-14 bar GIMEP, EGR of 0 to 12.5%, and lambda of 0.8 to 1.3 with a certification fuel (Haltermann 437, with RON=96.6 and MON=88.5). An algorithm has been devised to identify the knock point on individual pressure traces so that the large data set (of some thirty three thousand cycles) could be processed automatically. For lean and for rich operations, the role of the excess fuel, air, and recycled gas (which has excess air in the lean case, and hydrogen and carbon monoxide in the rich case) may be treated as effective diluents in the ignition delay expression.
2016-04-05
Technical Paper
2016-01-0704
Jacob McKenzie, Wai K. Cheng
Traditional analysis of the SI engine knocking process focuses on the auto-ignition process. This paper considers instead the combustion process after auto-ignition. The three classical modes of knock combustion are discussed in terms of the energy release rate and the size of the exothermic center. In the “flame” mode, acoustic expansion of the exothermic center is fast enough to prevent local pressure build up; normal flame propagation is initiated by the ignited region without development of acoustic wave. In the “knock” mode, the local pressure build-up sets up a pressure wave which excites the engine structural vibration, but the wave is not sufficient to ignite the end gas; normal flame propagation is again initiated by the ignited region. In the “detonation” mode, the end gas is ignited by the pressure wave to create a very fast Chapman Jouguet type denotation. For the “knock” mode, a knock intensity (KI) is defined as the pressure oscillation amplitude.
2016-04-05
Technical Paper
2016-01-0666
Guillaume Bourhis, Jean-Pascal Solari, Virginie Morel, Roland DAUPHIN
The efficiency of spark ignition engines is usually limited by the appearance of knock, which is linked to fuel octane number (RON). If running the engine at its optimal efficiency requests a high octane number at high load, a lower octane number is less necessary at low load. Aramco, along with its long term partner IFP Energies nouvelles, has been developing a synergistic fuel-engine system where the engine is fed by a fuel with an octane number adjusted in real time, as needed basis, while running at its optimal efficiency. Two major steps are identified to develop this ‘Octane on Demand’ concept: - First, characterize the octane requirement needed to run the engine at its optimal efficiency over the entire map; - Then, select the best fuel couple including a base fuel and an octane booster to fit this concept.
2016-04-05
Technical Paper
2016-01-0702
Gautam Kalghatgi, Kai Morganti, Ibrahim Algunaibet, Mani Sarathy, Robert Dibble
The phasing of knock onset in a PFI engine using a gasoline could be predicted using a simple equation for ignition delay of an appropriate surrogate fuel made up of toluene and PRF (TPRF) as shown in an earlier paper- SAE 2015-01-0757. The applicability of this approach is confirmed in this paper in a different engine using different fuels of different RON and sensitivity and different composition – including ethanol blends. An Arrhenius type equation with a pressure correction is found from interpolation of previously published data for any gasoline if its RON and sensitivity are known. Then, using the measured pressure and estimated temperature in the unburned gas, the ignition delay is found at different crank angles for an individual knocking cycle. Then the Livengood-Wu integral is estimated as a function of crank angle to predict the occurrence of knock.
2016-04-05
Technical Paper
2016-01-0678
Haifeng Lu, Jun Deng, Zongjie Hu, Zhijun Wu, Liguang Li, Fangen Yuan, Degang Xie, Shuang Yuan, Yuan Shen
China’s State Council has released the Energy-Saving and New Energy Vehicle Industrialization Plan, which states an expected fleet average target of 5.0L/100km by 2020. This means that the OEMs must apply much more advanced technologies to their production models. Compared to the EGR technology in diesel engines, the gasoline engine EGR is not a large-scale application in the market. But it has a promising potential to optimize the fuel economy for its anti-knock effect, pumping loss reduction and compatibility to the three-way catalyst. In this research, a 1.3L turbocharged PFI gasoline engine was used to evaluate the LP(low pressure) water-cooled EGR technology. The operating conditions vary from 1500rpm to 3000rpm and BMEP from 2bar to 17bar, and the common engine operating points in NEDC cycle are tested separately. Meanwhile, the compression ratio is changed from 9.5 to 10.5 to get higher fuel efficiency.
2016-04-05
Technical Paper
2016-01-1277
Monis Alam, Ashish Jaiswal, Jatin Agarwal, Ketan Yadav, Naveen Kumar
Gasoline has become a major fuel in transportation, its good calorific value and high volatility have made it suitable for use in different injection methods. The drastic increase in use of carbon based fuel has led to increase in harmful emissions, this resulted in implementation of stricter emissions norms. These harmful emissions include carbon monoxide and NOx. To meet the new norms and reduce the harmful emissions better techniques has to be implemented to achieve better combustion of gasoline. One such way of doing this is by enriching gasoline with hydrogen, due to its low activation energy and high calorific value the high energy released from hydrogen can be used to achieve complete combustion of gasoline fuel. There are certain drawbacks to the use of hydrogen in spark ignition engine, knocking and overheating of engine parts are the major of them.
2016-04-05
Technical Paper
2016-01-0701
Katsuya matsuura, Keito Nakano, Keisuke Shimizu, Norimasa Iida, Yoshihisa Sato
Knock is a factor hindering enhancement of the thermal efficiency of spark-ignition engines, and is a non-steady phenomenon that does not necessarily occur each cycle. In addition, the heat release rate of the flame during propagation also fluctuates each cycle, and the auto-ignition process of the unburned mixture (end-gas) compressed by expansion of the burned gas is affected by this fluctuation. Auto-ignition of the end-gas is the origin for knock manifestation. Therefore, this study focused on the flame heat release fluctuation, and used zero-dimensional detailed chemical reaction calculations in an attempt to analyze and examine the effects on the end-gas compression and auto-ignition process of changes in the i) start of combustion, ii) combustion duration and iii) center of heat release. The results showed that the end-gas compression speed varies according to the heat release pattern of the flame, and the ignition delay is affected by the compression speed.
2016-04-05
Technical Paper
2016-01-0830
Takashi Nomura, Shigehiko Sato, Jumpei Takahashi, Masayuki Ichiyanagi
In emerging countries, unstable fuel property sometimes deviates from each country’s standard is concerned to make many fuel related issues. Injector clogging issue which is caused by deposit is one of them. About the nozzle deposit of the direct injection (DI) injector of the gasoline engine, the forming mechanism and the cleaning effect with the cleaners which is often called deposit control additives, is reported much until now. However, in these past several years, the engine system equipped with both injectors of DI and port fuel injection (PFI) is commercially available. We developed new injector cleaner by improving existing DI injector cleaner which PEA (polyether amine) is contained as a cleaning component. At first, we analyzed PFI deposit to make the cleaning target clear. Then it was found that deposit of PFI included an aromatic oxide and a sulfate as chief ingredients.
2016-04-05
Technical Paper
2016-01-1069
Masayoshi Otaka, Taro Kasahara, Kenichi Komaba
As a means of further improving combustion efficiency of gasoline engine, an increase in compression ratio, which enhances the risk of knocking, is thinkable. To optimize engine combustion parameters, a technology that can precisely detect knocking is desirable. Presently skillful experts have been evaluating knocking subjectively by listening to radiation noise so far. The authors developed a device that can precisely detect knocking by means of processing sound signals, which are captured by a high-performance microphone that is sensitive in the wide frequency range. Shock waves induced by knocking cause in-cylinder gas vibrations that emits metallic hit noises from the outer engine wall. We studied how to identify the feature values of frequency characteristics when knocking occurs, under the assumption that the engine radiation noise includes more than 2nd-order harmonic components with respect to the basic frequency of the in-cylinder gas vibration mode.
2016-04-05
Technical Paper
2016-01-1343
Vivek Yadav, Krishnan Karthikeyan, WASIM AKRAM SHAIKH, Ganesh DACHARUM, Keerthi B M
In recent years the demand for high power to weight ratio with reduced fuel consumption and emission reduction have forced the development of new engine technologies. Turbocharging and direct injection are main technologies used for energy-saving gasoline engines. The biggest challenge in gasoline engines is high operating speeds which demand light weight rotating and reciprocating components. Also gasoline engines experience super-knocking events which can generate extremely high pressure pulses and may damage the engine components. The predominant failure mode in these cases is connecting rods buckling. It becomes of vital importance to design connecting rod for buckling safety. Two major factors which affects the bucking strength of connecting rod are shank dimensions and load offset in crankpin axis. There are standard methods available for calculating buckling strength of connecting rod such as Johnson’s buckling equation, Eigenvalue method, Merchant-Rankine formula etc.
2016-04-05
Technical Paper
2016-01-0833
Lei Meng, Yuqiang Li, Karthik Nithyanandan, Timothy Lee, Chunnian Zeng, Chia-Fon Lee
To face the challenges of fossil fuel shortage and air pollution problems, there is growing interest in the potential usage of alternative fuels such as bio-ethanol and bio-butanol in internal combustion engines. The literature shows that the acetone in the Acetone-Butanol-Ethanol (ABE) blends plays an important part in improving the combustion performance and emissions, owing to its higher volatility. In order to study the effects of acetone addition into commercial gasoline, this study focuses on the differences in combustion, performance and emission characteristics of a port-injection spark-ignition engine fueled with pure gasoline (G100), ethanol-containing gasoline (E30) and acetone-ethanol-gasoline blends (AE30 at A:E volumetric ratio of 3:1). The tests were conducted at 1200RPM with the default calibration (for gasoline), at 3 bar and 5 bar BMEP under various equivalence ratios.
2016-04-05
Technical Paper
2016-01-1009
Xin Wang, Yunshan Ge, Chuanzhen Zhang, Jia Liu, Zihang Peng, Huiming Gong
Along with the booming expansion of private car preservation, many Chinese cities are now struggling with haze weather and ground-level ozone contamination. Although central government has stepped up efforts to purify skies above China, counter-strategies to curb ground-level ozone is comparatively weaker. By using maximum incremental reactivity (MIR) method, this paper estimated ozone potential of tailpipe emissions, including criteria emissions, C1-C7 carbonyls and benzenes, from twenty-five China-3 to China-5 (Equivalent to Euro-3 to Euro-5) passenger cars fueled with conventional gasoline, methanol-gasoline, ethanol-gasoline, neat methanol and compressed natural gas (CNG). The results showed that, specific reactivity (SR) of Euro-3 to Euro-5 gasoline-powered cars was 5.39, 4.55 and 4.15 g O3/g VOC, respectively. Compared to gasoline counterparts, alternative-fuel basically exhibited lower SR.
2016-04-05
Technical Paper
2016-01-0748
Vijai Shankar Bhavani Shankar, Muhammad Sajid, Khalid Al-Qurashi, Nour Atef, Issam Alkhesho, Ahfaz Ahmed, Sukho Chung, William Roberts, Kai Morganti, Mani Sarathy
Primary Reference Fuels (PRFs), binary mixtures of n-heptane and iso-octane based on Research Octane Number (RON), have been popular gasoline surrogates for spark ignition engines. The adoption of these two component surrogates to represent real gasolines for simulations of HCCI/PCCI engines needs consideration, as the mode of combustion is very different in these engines (i.e., the combustion process is solely controlled by the reactivity of the fuel). This study is an experimental evaluation of RON based PRF surrogates of four real gasoline fuels named FACE A, C, I, and J in a CFR (Cooperative Fuels Research) engine running in HCCI mode. This mode of operation allowed for the evaluation of surrogate mixtures from purely a chemical kinetic perspective. The gasoline fuels considered in this study have very low sensitivities, S (RON-MON), and exhibit two-stage ignition behaviour.
2016-04-05
Technical Paper
2016-01-0831
Young Suk Jo, Leslie Bromberg, John Heywood
Downsizing a spark ignition engine with a turbocharger in a vehicle is a widely used method for improving vehicle fuel consumption. By increasing maximum torque, the typical operating region of the engine shifts up to where pumping and heat transfer losses are relatively lower. This improves engine brake efficiency, but results in higher in-cylinder pressures and temperatures which increase the likelihood of engine knock above that of naturally-aspirated engines. High octane fuel (e.g. E85) effectively suppresses knock, but the octane rating of such fuels are much above what is required under normal driving conditions. To overcome this issue, there have been attempts to use octane more effectively by means of Octane on Demand (OOD): higher octane fuel is used only when needed. Practical applications of OOD are dual fuel injection or On Board fuel Separation (OBS): the dual fuel approach utilizes a separate tank of E85, and OBS extracts a high ethanol content fuel stream (e.g.
2016-04-05
Technical Paper
2016-01-0785
Martin Kirsten, Gerhard Pirker, Christoph Redtenbacher, Andreas Wimmer, Franz Chmela
As emission limits become increasingly stringent and the price of gaseous fuels decreases, more emphasis is being placed on promoting gas engines. In the field of large engines for power generation, dual fuel combustion concepts that run on diesel/natural gas are particularly attractive. Knock in diesel/natural gas dual fuel engines is a complex, well-known phenomenon that must always be taken into consideration in attempts to increase load and efficiency. Thus combustion concept development requires a reliable yet robust methodology for detecting knock in order to ensure knock-free engine operation. Operating parameters such as substitution rate, rail pressure and start of current are the factors that influence oscillations on the in-cylinder pressure trace after the start of combustion. Oscillations in the pre-mixed combustion phase, or ringing, are caused by the rapid conversion of larger parts of the injected diesel.
2016-04-05
Technical Paper
2016-01-0806
James Sevik, Michael Pamminger, Thomas Wallner, Riccardo Scarcelli, Ronald Reese, Asim Iqbal, Brad Boyer, Steven Wooldridge, Carrie Hall, Scott Miers
In recent times, interest in natural gas as a fuel for light-duty transportation has increased due to its domestic availability and lower cost relative to gasoline. Natural gas, comprised mainly of methane, has a higher knock resistance than gasoline making it advantageous for high load operation. However, the higher resistance to knock can cause ignitability issues at part-load operation leading to an increase in the initial flame development process. Part-load exhaust gas recirculation tolerance can also be affected by the lower flame speed of natural gas. While port-fuel injection of natural gas can lead to a loss in power density due to the displacement of intake air, injecting natural gas directly into the cylinder can reduce such losses. A study was designed and performed to evaluate the potential of natural gas for use as a light-duty fuel.
2016-04-05
Technical Paper
2016-01-0889
Chuang Fan, Sunyu Tong, Xiaohong Xu, Jing Li, Xiao Yu He, Jun Deng, Liguang Li
Downsizing gasoline direct injection engine with turbo boost technology is the main trend for gasoline engine. However, with engine downsizing and ever increasing of power output, a new abnormal phenomenon, known as pre-ignition or super knock, occurs in turbocharged GDI engine. Pre-ignition will cause very high in-cylinder pressure and high oscillations. In some circumstances, one cycle of severe pre-ignition can damage the piston or spark plug, which has a severe influence on engine performance and service life. So pre-ignition has raised lots of attention in both industry and academic society. More and more studies reveal that the auto-ignition of lubricants is the potential cause for pre-ignition. The auto-ignition characteristics of different lubricants are studied. This paper focuses on the ignition delay of different lubricants in Controllable Active Thermo-Atmosphere (CATA) combustion system.
2016-04-05
Technical Paper
2016-01-0087
Fengrong Bi, Teng Ma, Jian Zhang
This paper reports an investigation of knock detection in spark ignition (SI) engines using EEMD-Hilbert transform based on the engine cylinder block vibration signals. The power density spectrum estimation was done to the processed signal to find the featured frequency band of knock inspired vibration. Ensemble Empirical Mode Decomposition (EEMD) was used to de-compose the de-noised signal. Hilbert transform was used to detect knock feature. The result shows that in the knock combustion cycle, the instantaneous frequency of IMF is relative stability. And in the normal combustion cycle, the instantaneous frequency is fluctuation sharply. At last, the knock window was then determined, based on which a new knock intensity evaluation factor K was proposed.
2016-04-05
Technical Paper
2016-01-0834
Arjun Prakash, Roger Cracknell, Vinod Natarajan, David Doyle, Aaron Jones, Matthew Hinojosa, Peter Lobato
Octane appetite of modern engines has changed as engine designs have evolved to meet performance, emissions, fuel economy and other demands. The octane appetite of seven modern vehicles was studied in accordance with the octane index equation OI=RON-KS, where K is an operating condition specific constant, and S is the fuel sensitivity (RON-MON). Engines with a displacement of 2.0L and below and different combinations of boosting, fuel injection, and compression ratios were tested using a decorrelated RON-MON matrix of eight fuels. Power and acceleration performance was used to determine the K values for corresponding operating points. Previous studies have shown that vehicles manufactured up to 20 years ago mostly exhibited negative K values and the fuels with higher RON and higher sensitivity tended to perform better.
2016-02-01
Technical Paper
2016-28-0152
A S Ramadhas, Punit Kumar Singh, P Sakthivel, Reji Mathai, Ajay Kumar Sehgal
Abstract Alcohols are preferred choice of alternative fuel for gasoline engines to tackle the problems associated with nation’s energy security and environmental pollution. Ethanol can be used as a sole fuel or gasoline blending component for use in spark ignition engines. BIS Specification 2796: 2013 permitted to blend 10% ethanol in gasoline and the concentration may be further increased in coming years in India. Research on combustion of ethanol blended gasoline on modern gasoline engine is highly desirable. This paper highlights the experimental investigation carried out on the latest generation multipoint fuel injection system passenger car engine fueled with ethanol-gasoline blends in a climatic controlled test cell to study the in-cylinder combustion, performance and emission characteristics. Part load tests at regular speed intervals were conducted using ethanol blends. Combustion duration decreased with increase in engine load and speed for the all test fuels.
2015-11-17
Technical Paper
2015-32-0728
Tomoaki Yatsufusa, Shinsuke Miyata, Koji Ishibashi
A new technic to measure the propagating flame precisely by using densely installed multiple ion-probes has been developed. This system targets the high-intensity and pulsatile combustion, including knocking in gasoline engine, and oscillating combustion in burner or gas turbine combustor. In such environment, observation of details in the combustor by visualization is generally limited because of the strength of observation window. In contrast, ion-probe is physically and thermally strong enough to endure such environment. In the present study, characteristics of the combustion measurement were investigated using the different types of propagating flame with various LPG-oxygen-nitrogen mixtures. The composition of the mixture was stoichiometric LPG-oxygen diluted with nitrogen. Nitrogen dilution ratio was varied to control the flame propagation velocity.
2015-11-17
Technical Paper
2015-32-0807
Takashi Shimada, Yuki Yoshida, Chibin Rin, Masanori Yamada, Naoya Ito, Akira Iijima, Koji Yoshida, Hideo Shoji
Homogeneous Charge Compression Ignition (HCCI) engines have attracted much attention and are being widely researched as engines characterized by low emissions and high efficiency. However, one issue of HCCI engines is their limited operating range because of the occurrence of rapid combustion at high loads and misfiring at low loads. It is known that knocking accompanied by in-cylinder pressure oscillations also occurs in HCCI engines at high loads, similar to knocking seen in spark-ignition engines. In this study, HCCI combustion accompanied by in-cylinder pressure oscillations was visualized by taking high-speed photographs of the entire bore area. In addition, the influence of internal exhaust gas circulation (EGR) on HCCI knocking was also investigated. The visualized combustion images revealed that rapid autoignition occurred in the end-gas region during the latter half of the HCCI combustion process when accompanied by in-cylinder pressure oscillations.
2015-09-29
Technical Paper
2015-01-2811
Tingjun Hu, Ho Teng, Xuwei Luo, Chun Lu, Jiankun Luo
Abstract The relationship between fuel dilution of the crankcase oil and low-speed pre-ignition (LSPI) was studied experimentally with a highly-boosted 1.8L turbocharged gasoline direct injection (TGDI) engine fueled with RON93 gasoline. It was found that properties of oil particles entered the engine cylinder were affected significantly by fuel dilution. The gasoline content in the oil represents those with long carbon chain or heavy species in gasoline, with much lower boiling points and auto ignition temperatures than those for the undiluted engine oil. Thus, dilution of the engine oil by these gasoline species lowers the volatility and the minimum auto ignition temperature of the engine oil. With 15% fuel content in the oil, the flash point and the fire point of the SAE 5W30 oil dropped from 245 °C to 90 °C and from 265 °C to 150 °C, respectively.
2015-09-06
Technical Paper
2015-24-2432
Michela Costa, Paolo Sementa, Ugo Sorge, Francesco Catapano, Guido Marseglia, Bianca Maria Vaglieco
Abstract Present work investigates both experimentally and numerically the benefits deriving from the use of split injections in increasing the engine power output and reducing the tendency to knock of a gasoline direct injection (GDI) engine. The here considered system is characterized by an optical access to the combustion chamber. Imaging in the UV-visible range is carried out by means of a high spatial and temporal resolution camera through an endoscopic system and a transparent window placed in the piston head. This last is modified to allow the view of the whole combustion chamber almost until the cylinder walls, to include the so-called eng-gas zones of the mixture, where undesired self-ignition may occur under some circumstances. Optical data are correlated to in-cylinder pressure oscillations on a cycle resolved basis.
2015-09-06
Technical Paper
2015-24-2449
Mark Aaron Hoffman, Zoran Filipi
The limited operational range of low temperature combustion engines is influenced by near-wall conditions. A major factor is the accumulation and burn-off of combustion chamber deposits. Previous studies have begun to characterize in-situ combustion chamber deposit thermal properties with the end goal of understanding, and subsequently replicating the beneficial effects of CCD on HCCI combustion. Combustion chamber deposit thermal diffusivity was found to differ depending on location within the chamber, with significant initial spatial variations, but a certain level of convergence as equilibrium CCD thickness is reached. A previous study speculatively attributed these spatially dependent CCD diffusivity differences to either local differences in morphology, or interactions with the fuel-air charge in the DI engine. In this work, the influence of directly injected gasoline on CCD thermal diffusivity is measured using the in-situ technique based on fast thermocouple signals.
2015-09-06
Technical Paper
2015-24-2473
Alessandro Montanaro, Luigi Allocca, Giovanni Meccariello, Maurizio Lazzaro
Abstract In internal combustion engines, the direct injection at high pressures produces a strong impact of the fuel on the combustion chamber wall, especially in small-bore sizes used for passenger cars. This effect is relevant for the combustion process resulting in an increase of the pollutant emissions and in a reduction of the engine performances. This paper aims to report the effects of the injection pressure and wall temperature on the macroscopic behavior and atomization of the impinging sprays on the wall. The gasoline spray-wall interaction was characterized inside an optically accessible quiescent chamber using a novel make ready Z-shaped schlieren-Mie scattering set-up using a high-speed C-Mos camera as imaging system. The arrangement was capable to acquire alternatively the schlieren and Mie-scattering images in a quasi-simultaneous fashion using the same line-of-sight.
2015-09-06
Technical Paper
2015-24-2490
Francesco Catapano, Silvana Di Iorio, Paolo Sementa, Bianca Maria Vaglieco
Abstract Ethanol is the most promising alternative fuel for spark ignition (SI) engines, that is blended with gasoline, typically. Moreover, in the last years great attention is paid to the dual fueling, ethanol and gasoline are injected simultaneously. This paper aims to analyze the better methods, blending or dual fueling in order to best exploit the potential of ethanol in improving engine performance and reducing pollutant emissions. The experimental activity was carried out in a small displacement single cylinder engine, representative of 2-3 wheel vehicle engines or of 3-4 cylinder small displacement automotive engines. It was equipped with a prototype gasoline direct injection (GDI) head. The tests were carried out at 3000, 4000, and 5000 rpm full load. The investigated engine operating conditions are representative of the European homologation urban driving cycle.
2015-09-06
Technical Paper
2015-24-2525
Luigi De Simio, Sabato Iannaccone, Michele Gambino, Veniero Giglio, Natale Rispoli, Gianluca Barbolini, Dario Catanese, Marco Ferrari, Walter Lo Casale
This paper presents an experimental study on a 2-stroke SI engine, used on small portable tools for gardening or agriculture, aimed to identify possible correlations between parameters related to ionization current and air/fuel mixture richness, considering different fuels and spark plug wear. This, to realize a simple system to control the engine parameters and adapt them to engine aging and fuel type changing. The engine was fed with commercial gasoline, low octane number gasoline, alkylate gasoline and a blend of 80% gasoline and 20% ethanol. In all tests carried out with varying engine speed and spark advance the ionization signal was characterized by a single peak, resulting in the impossibility of distinguishing chemical and thermal ionization. All data collected were analyzed looking for correlations between all the available data of CO emissions and several characteristic parameters obtained from the ionization signal.
2015-09-06
Journal Article
2015-24-2429
Enrico Corti, Claudio Forte, Gian Marco Bianchi, Davide Moro
Knocking combustions heavily influence the efficiency of Spark Ignition engines, limiting the compression ratio and sometimes preventing the use of Maximum Brake Torque (MBT) Spark Advance (SA). A detailed analysis of knocking events can help in improving the engine performance and diagnostic strategies. An effective way is to use advanced 3D Computational Fluid Dynamics (CFD) simulation for the analysis and prediction of the combustion process. The standard 3D CFD approach based on RANS (Reynolds Averaged Navier Stokes) equations allows the analysis of the average engine cycle. However, the knocking phenomenon is heavily affected by the Cycle to Cycle Variation (CCV): the effects of CCV on knocking combustions are then taken into account, maintaining a RANS CFD approach, while representing a complex running condition, where knock intensity changes from cycle to cycle.
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