Application of a diagnostic technique for evaluating the quality of the air–fuel mixture and the ignition quality of a spark-ignition reciprocating aircraft piston engine

Author(s):  
AK Antonopoulos ◽  
RG Papagiannakis ◽  
DT Hountalas

The performance characteristics of an aircraft piston engine are affected mainly by the air–fuel mixture quality (i.e. condition of the fuel injection system) and by the spark timing and spark duration (i.e. condition of ignition system). Thus, the present work focuses on investigating the effect of both fuel injection and spark ignition systems on performance characteristics of two aircraft piston engines which are of the same type but have overhauled by two different workshops. The investigation is conducted by applying an existing diagnostic technique, which is based on the simultaneous recording and processing of two electric signals: one corresponding to cylinder pressure and the second corresponding to the ignition system. The basic characteristics of the proposed methodology are simplicity and field applicability on engines of this type. A detailed experimental investigation has been conducted on the aforementioned two aircraft piston engines on a dedicated test bench. From the results, it is revealed that the proposed diagnostic methodology provides reliable information for the effect of both the ignition and fuel injection systems on engine performance characteristics. The results derived from the specific work enable the comparative evaluation of the engines and their ignition and fuel injection systems. Finally, based on this first investigation, the proposed methodology seems to be promising, because it can be easily applied on any type of spark-ignited engine and especially on aircraft piston engine, where due to its geometry and multicylinder nature, the application of lab techniques on the field is, if not impossible, extremely difficult.

Author(s):  
Moch Miftahul Arifin ◽  
Nasrul Ilminnafik ◽  
Muh. Nurkoyim Kustanto ◽  
Agus Triono

Technological developments in diesel engines require improvements to the fuel injection system to meet the criteria for economical, high-power and efficient combustion and meet environmental regulatory standards. One method that has a lot of interest is changing the characteristics of the fuel, with the aim of producing optimal combustion. Spray characteristics have a big role in determining the quality of combustion in diesel engines. A good spray can improve the quality of fuel atomization and the homogeneity of the air-fuel mixture in the combustion chamber so that it can produce good engine performance and low emissions. This study aims to determine the effect of a diesel-biodiesel (Calophyllum inophyllum)-gasoline blendandfuel heating on the spray characteristics. The research was conducted with variations in composition (B0, B100, B30, B30G5 and B30G10) and fuel heating (40, 60, 80, and 100 °C). Fuel injected atapressure of 17 MPa in to a pressure chamber of 3 bar. The spray formed was recorded with a high-speed camera of 480 fps (resolution 224x168 pixel). In B100 biodiesel, the highest viscosity and density cause high spray tip penetration, small spray angle, and high spray velocity. The addition of diesel oil, gasoline, and heating fuel reduces the viscosity and density so that the spray tip penetration decreases, the spray angle increases and the velocity of spray decreases.


Author(s):  
T Wang ◽  
Z Peng ◽  
S-L Liu ◽  
H-D Xiao ◽  
H Zhao

The potential of lean burn in a spark-ignition (SI) engine with optimized fuel injection was experimentally investigated and numerically simulated. The experiments were carried out on a production SI engine which has a port fuel injection (PFI) system. The previous port electronic fuel injection system was modified and the technique of double-pulse fuel injection (DFI) was employed. By regulating injection timings and proportions of DFI, the air-fuel mixture stratification was significantly improved and the expected lean burn was implemented. The experimental results showed that the reduction of fuel consumption with DFI could be above 10 per cent over quite a wide load range, compared to single fuel injection. With optimized fuel injection timings and double-pulse proportions, the ideal engine performance and emissions can be achieved with a two to three times higher air-fuel ratio (AFR) than single fuel injection. With numerical simulation, the effects of mixture stratification formed by different fuel injection amounts and timings were analysed using a phenomenological model. The mixture in the cylinder was divided into different regions that distribute spherically around the spark plug and consist of a central region of stoichiometric air-fuel mixture and a gradually leaner outside region. Simulation results demonstrated that the improvements in fuel economy and emissions with DFI were mainly attributed to increased stratification zones and a reduced AFR gradient in the stratification zones.


Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Sebastian Różowicz

Abstract The paper presents the results of analytical and experimental studies concerning the influence of different kinds of fuel additives on the quality of the spark discharge for different configurations of the ignition system. The wear of the spark plug electrode and the value of spark discharge were determined for various impurities and configurations of the air-fuel mixture.


2018 ◽  
Vol 184 ◽  
pp. 01013
Author(s):  
Corneliu Cofaru ◽  
Mihaela Virginia Popescu

The paper presents the research designed to develop a HCCI (Homogenous Charge Compression Ignition) engine starting from a spark ignition engine platform. The chosen test engine was a single cylinder, four strokes provided with a carburettor. The results of experimental research data obtained on this version were used as a baseline for the next phase of the research. In order to obtain the HCCI configuration, the engine was modified, as follows: the compression ratio was increased from 9.7 to 11.5 to ensure that the air – fuel mixture auto-ignite and to improve the engine efficiency; the carburettor was replaced by a direct fuel injection system in order to control precisely the fuel mass per cycle taking into account the measured intake air-mass; the valves shape were modified to provide a safety engine operation by ensuring the provision of sufficient clearance beetween the valve and the piston; the exchange gas system was changed from fixed timing to variable valve timing to have the possibilities of modification of quantities of trapped burnt gases. The cylinder processes were simulated on virtual model. The experimental research works were focused on determining the parameters which control the combustion timing of HCCI engine to obtain the best energetic and ecologic parameters.


2020 ◽  
Vol 181 (2) ◽  
pp. 11-18
Author(s):  
Mariusz CHWIST ◽  
Michał GRUCA ◽  
Michał PYRC ◽  
Magdalena SZWAJA

The article presents results of investigation on the combustion of a mixture of oil from pyrolysis of tires and basic fuel in an internal combustion reciprocating piston engine. The tested fuel consisted of: diesel oil and oil from pyrolysis of tires at amount of 10% by volume. The tests were carried out on a single-cylinder naturally aspirated compression-ignition engine. The engine is equipped with a common rail fuel injection system and an electronic control unit that allows changing injection timing. A comparative analysis of pressure-volume charts for the reference fuel, which was diesel, and for a mixture of diesel with the addition of 10% oil from tire pyrolysis was carried out during the study. Injector characteristics for the reference fuel and the mixture were determined. Engine efficiency for both fuels was determined. Unrepeatability of the engine work cycles for the diesel fuel and the tested mixture was calculated. Finally, the share of toxic exhaust components in exhaust gases was analyzed. It was found that pyrolisys oil from tires can be used as additive to regular diesel fuel at amount up to 10%, however, toxic exhaust gases emission was increased.


Author(s):  
Shu-Liang Liu ◽  
Tian-You Wang ◽  
Hong-Jun Su ◽  
Xing Li ◽  
Jian-Wen Li ◽  
...  

The intake system of a 2-Valve TJ376QE gasoline engine was modified so that its intake swirl and tumble motions were considerably intensified. The stronger air motions are helpful to organize air and fuel mixture strength distribution. The previous port electronic fuel injection system was modified and the technique of TEFI (Twice Electronic Fuel Injection per cycle) is employed. Through regulations of the two injection timings and proportions, an adequate air and fuel mixture stratification–quasi-homogenous mixture was produced and the lean burn can be realized in a product 2-valve S.I. engine. The experimental results show that the scope of bsfc reduction can be >10 % at quite wide load range by ether 1 injection or by 2 injections. Comparing to the conventional single injection, a leaner mixture can be used by TEFI and an even more reduced fuel consumption of 5% was reached by 2 injections. The optimized values of A/F ratio can be higher by 2–3 units of A/F than that of the single injection method. The TEFI can reduce NOx emission by 35–50% than that of single injection at engine load (bmep) range of 0.20–0.75 (MPa).


2016 ◽  
Vol 823 ◽  
pp. 291-296 ◽  
Author(s):  
Ion Lespezeanu ◽  
Florin Marius Militaru ◽  
Octavian Alexa ◽  
Constantin Ovidiu Ilie ◽  
Marin Marinescu

Flow corrections established based on Lambda control system of spark ignition engines, determines in a decisively way the quality of air-fuel mixture. Faults in the operation of the control system generates deviations of the mixture composition from stoichiometric report, in this way affecting the entire combustion process in engine cylinders. This phenomenon leads, among others, to changes regarding the density of pollutant emissions from exhaust gases. In this context, this paper presents experimental researches made using the simulation of faults that may occur in the control system to highlight their influence on the concentration of engine emissions.


2020 ◽  
Author(s):  
Jinlong Liu ◽  
Christopher Ulishney ◽  
Cosmin E. Dumitrescu

Abstract Partial conversion of the large inventory of compression-ignition engines to natural-gas (NG) spark-ignition lean-burn operation can reduce U.S. dependence on imported petroleum and enhance national energy security. This paper describes some of the observations made during such an engine conversion and proposes some solutions to alleviate some of the potential issues. The engine conversion in this study consisted from replacing the diesel injector with a spark plug and adding a port fuel injection system for NG delivery. The results indicated that the retrofitted engine performed reliably at lean-burn conditions, despite the different combustion characteristics compared to conventional SI engines. However, the squish region will trap an important fuel fraction (∼30%) and experience less-optimal burning conditions, hence a slower burning rate. This affected the engine efficiency and increased the unburned hydrocarbon and carbon monoxide emissions. From a combustion point of view, the operation of such converted engines can be optimized by increasing the bowl-to-squish volume ratio, optimizing the piston shape (e.g., by removing the central protrusion and avoiding 90-degree edges inside the bowl). The original compression ratio may also need to be reduced to avoid knocking. Moreover, direct gas injection and/or intake charging will increase the volumetric efficiency, which will benefit engine efficiency and emissions.


2015 ◽  
Vol 779 ◽  
pp. 187-191
Author(s):  
Hao Ling Ren ◽  
Tian Liang Lin ◽  
Hai Bo Xie

The poor scavenging process of the hydraulic free piston engine which uses two-stroke engine as its driver was presented. A two-cylinder, four-stroke diesel engine was proposed to drive the single-piston hydraulic free piston engine to improve the scavenging process. The intake and release valves mechanism and fuel injection system were redesigned to adapt the performance of the single-piston hydraulic free piston engine. Feasibility and reliability of this new structure are verified through simulation.


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