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Technical Paper

Effects of Ignition Control on Combustion Process Non-Repeatability in an Aircraft Radial Piston Engine

2020-09-15
2020-01-2044
The ignition method significantly affects the combustion process in piston aircraft engines. This paper presents the results of bench tests of two variants of the radial piston aircraft engine: equipped with a standard magneto system and an electronic dual ignition system. The engine was tested in steady states for operating points defined by rotational speed and load. Their values corresponded to a load ranging from 50% of nominal power to take-off power. The ignition advance angle was constant for the engine equipped with ignition magnetos, while for the second engine variant it was determined by the developed algorithm introduced to the electronic ignition system control unit. The analysis of the combustion process was based on pressure measurements in one cylinder.
Technical Paper

Effect of Jet-Jet Angle on Combustion Process of Diesel Spray in an RCEM

2020-09-15
2020-01-2058
The effects of jet-jet angle on the combustion process were investigated in an optical accessible rapid compression and expansion machine (RCEM) under various injection conditions and intake oxygen concentrations. The RCEM was equipped with an asymmetric six-hole nozzle having jet-jet angles of 30° and 45°. High-speed OH* chemiluminescence imaging and direct photo imaging using the Mie scattering method captured the transient evolution of the spray flame, characterized by lift-off length and liquid length. The RCEM operated at 1200 rpm. The injection timing was -5°ATDC, and the in-cylinder pressure and temperature were 6.1 MPa and 780 K at the injection timing, respectively, which achieved a short ignition delay. The effects of injection pressure, nozzle hole diameter, and oxygen concentration were investigated.
Technical Paper

Experimental Investigation of Injection Strategies to Improve Intelligent Charge Compression Ignition (ICCI) Combustion with Methanol and Biodiesel Direct Injection

2020-09-15
2020-01-2072
Applications of methanol and biodiesel in internal combustion engines have raised widespread concerns, but there is still huge scope for improvement in efficiency and emissions. The brand-new combustion mode, named as Intelligent Charge Compression Ignition (ICCI) combustion, was proposed with methanol-biodiesel dual fuel direct injection. In this paper, effects of injection parameters such as two-stage split-injections, injection timings, injection pressure and intake pressure on engine combustion and emissions were investigated at IMEP = 8, 10, and 12 bar. Results show that the indicated thermal efficiency up to 53.5% and the NOx emissions approaching to EURO VI standard can be obtained in ICCI combustion mode.
Technical Paper

GDI Sprays with up to 200 MPa Fuel Pressure and Comparison of Diesel-like and Gasoline-Like Injector Designs

2020-09-15
2020-01-2104
To address stricter emission limits, GDI develops to increased fuel pressure. Current gasoline injectors are already operating at a pressure of up to 35 MPa and an elevation is still promising lower particle emissions and increased efficiency. There have been only few studies of GDI sprays at pressures >50 MPa published. Contrary, in diesel engines injection pressure up to 250 MPa are common. GDI and diesel injector designs limit liquid penetration in different ways to avoid wall wetting, which has a negative impact on emissions in GDI combustion concepts. With elevated fuel pressure the question arises which design concept limits the penetration depth more effectively. To investigate the properties of high pressure sprays, a GDI injector (100 MPa max. fuel pressure) and an injector with diesel-like design are compared. High speed Shadowgraphy and Schlieren technique are used to gather information of liquid and vapor phase propagation.
Technical Paper

Comparison of the Effects of Different Biofuels on the Oxidation Stability of a Hydrocarbon Fuel

2020-09-15
2020-01-2101
In this work, the effects of the addition of biofuels belonging to different chemical families on the oxidation stability of a conventional fuel surrogate (n-decane) have been investigated. Experiments have been performed in a PetroOxy apparatus, which is one of the references Rapid Small Scale Oxidation Test of the ASTM 7545 methods. When the pressure in the cell of the device decreases by 10% of the maximum pressure recorded, the time measured to reach this target value defines the Induction Period (IP). IP constitutes a quantitative measure of the oxidation stability of the fuel. In addition to the IP measurements for each biofuel / hydrocarbon fuel blend, organic peroxides produced in the liquid sample were quantified at the IP, using iodometric titration and ultraviolet-visible spectrophotometry. Different oxygenated biofuels have been studied in this work: diethyl ether, n-butanol, and cyclopentanone.
Technical Paper

Numerical Investigation on GDI Spray under High Injection Pressure up to 100 MPa

2020-09-15
2020-01-2108
In recent years, the increase of gasoline fuel injection pressure is a way to improve thermal efficiency and lower engine-out emissions in GDI homogenous combustion concept. The challenge of controlling particulate formation as well in mass and number concentrations imposed by emissions regulations can be pursued improving the mixture preparation process and avoiding mixture inhomogeneity with ultra-high injection pressure values up to 100 MPa. The increase of the fuel injection pressure in GDI homogeneous systems meets the demand for increased injector static flow, while simultaneously improves the spray atomization and mixing characteristics with consequent better combustion performance. Few studies quantify the effects of high injection pressure on transient gasoline spray evolution. The aim of this work was to simulate with OpenFOAM the spray morphology of a commercial gasoline injected in a constant volume vessel by a prototypal GDI injector.
Technical Paper

An Experimental Facility for Rapid Testing of SCR Systems

2020-09-15
2020-01-2192
Urea-SCR (selective catalytic reduction) has become the principal technology used to lower NOx emissions in automotive compression ignition engines. Although the technology is well known and developed, the stricter emissions’ limits force engineers to implement new approaches to reduce warm-up time and improve the mixing process of the urea-water solution with the exhaust gases while avoiding a solid deposit formation. The exhaust system’s design is optimized using 3D numerical methods, but the validation of the design’s performance requires prototype testing on an engine dynamometer, where it is difficult to decouple and adjust the exhaust gas composition and temperature as in the numerical model; and thus it is problematic to verify the model. In this study we propose an experimental facility for rapid testing of SCR systems in simulated and precisely controlled engine-relevant conditions.
Technical Paper

Problems of Reducing Friction Losses of a Piston-Ring-Cylinder Configuration in a Combustion Piston Engine with an Increased Isochoric Pressure Gain

2020-09-15
2020-01-2227
Currently, there is a tendency to increase the mean workable pressure in internal combustion engines, to reduce their cylinder volume and the number of cylinders in a balanced manner, depending on the vehicle's class and weight in order to improve the thermal and mechanical efficiency of the engine. An increased engine torque at a slight angular velocity results in an increase in the mean value of the unit pressure distribution of the piston rings, especially the upper sealing ring in the initial period of the expansion stroke, which limits the slip effect affecting the ability to form an oil film. The essence of validity of increasing the isochoric degree of pressure gain is the use of vehicles at low speeds with a high torque. Such selection of parameters ensures good motion dynamics at low fuel consumption.
Technical Paper

Hybridized Diesel Powertrains for LCV Applications to Meet the Stringent 2025 Standards for Pollutant- and CO2-Emissions

2020-09-15
2020-01-2252
The ever-increasing pressure to reduce greenhouse gas (GHG) emissions from the transport sector poses challenges to the entire industry. Since the release of the new European CO2 fleet emission targets demanding a massive reduction in the upcoming years (-15%/-31% in 2025/2030 vs. the 2021 figures), substantial initiatives have been launched to ensure the development of affordable solutions. goals meeting the market requirements. Diesel powered vehicles and, especially Light-duty Diesel has been the main driver for CO2 emission reductions in recent years. These achievements were mainly based on improvement of combustion efficiency and reduction of mechanical losses. Based on this experience, it appears doubtful to achieve further significant fuel consumption and CO2 reductions with an improvement in engine technology alone. This reduction steps requested by the authorities call for the implementation of new technologies.
Technical Paper

Soot Load Monitoring in Gasoline Particulate Filter Applications with RF-Sensors

2020-09-15
2020-01-2171
With the start of Euro 6d regulations, gasoline particulate filters (GPF) have become standard equipment in European vehicles with gasoline-direct-injection engines. GPFs will also be broadly applied to meet the upcoming China 6 regulations. An existing challenge with GPFs is accurate soot load detection to manage the pressure loss across the exhaust system and to protect the GPFs from soot overload, which could potentially cause damage as result of uncontrolled soot oxidations. Systems with the GPF located in the under-floor position have a higher potential risk of soot overload due to lower temperatures, which can result in higher soot accumulation rates. The accuracy of existing soot estimation methods such as evaluation of the pressure drop of the soot-loaded GPF or model-based balancing of soot accumulation versus soot oxidation rates are sensitive to transient operating condition of a vehicle.
Technical Paper

Study on the Pre-Chamber Fueling Ratio Effect on the Main Chamber Combustion Using Simultaneous PLIF and OH* Chemiluminescence Imaging

2020-09-15
2020-01-2024
Pre-chamber combustion (PCC) enables leaner air-fuel ratio operation by improving its ignitability and extending flammability limit, and consequently, offers better thermal efficiency than conventional spark ignition operation. The geometry and fuel concentration of the pre-chamber (PC) is one of the major parameters that affect overall performance. To understand the dynamics of the PCC in practical engine conditions, this study focused on (i) correlation of the events in the main chamber (MC) with the measured in-cylinder pressure traces and, (ii) the effect of fuel concentration on the MC combustion characteristics using laser diagnostics. We performed simultaneous acetone planar laser-induced fluorescence (PLIF) from the side, and OH* chemiluminescence imaging from the bottom in a heavy-duty optical engine. Two different PC Fueling Ratios (PCFR, the ratio of PC fuel to the total fuel), 7%, and 13%, were investigated.
Standard

Heat Treatment of Steel Raw Materials

2020-09-01
CURRENT
AMSH6875C
This specification covers the requirements for heat-treatment of four classes of steel (See 1.2) and the requirements for furnace equipment, test procedures and information for heat-treating procedures, heat-treating temperatures and material (See 6.3) test procedures. This specification is applicable only to the heat treatment of raw material (See 6.3.1); it does not cover the requirements for the heat treatment of steel parts (See 3.4 and 6.3.2). This specification also describes procedures that, when followed, will produce the desired properties and material qualities within the limitations of the respective alloys tabulated in Tables 1A, 1B, 1C and 1D. Alloys other than those specifically covered herein may be heat treated using all applicable requirements of this specification.
Standard

Air Dryer Test Procedure

2020-08-26
CURRENT
J2384_202008
This SAE Recommended Practice establishes uniform test procedures for desiccant air dryers used in vehicles with compressed air systems per SAE J2383. Continuous flow desiccant air dryers are excluded from the scope of this document.
Standard

Spark Arrester Test Procedure for Medium Size Engines

2020-08-21
WIP
J350
This SAE Recommended Practice establishes equipment and procedures for testing spark arresters used on medium-size, single-position internal combustion engines, normally used in transportable, stationary, and vehicular applications, such as highway trucks, agricultural tractors, industrial tractors, other mobile equipment, and motorcycles. This document provides two methods of testing (laboratory testing and engine testing) which may be used to evaluate a spark arrester. It also includes special requirements for screen type devices and an endurance test procedure for screen type spark arresters.
Standard

Spark Arrester Test Procedure for Large Size Engines

2020-08-21
WIP
J342
This SAE Recommended Practice establishes equipment and procedures for the evaluation of the effectiveness and other performance characteristics of spark arresters or turbochargers used on the exhaust system of large engines normally used in a railroad locomotive, stationary power plant, and other similar applications. This document does not cover applications requiring flame arresting, exhaust gas cooling, or isolation from explosive gases. Two test methods are presented; a laboratory test using ambient air (cold test) and an engine test using exhaust gases (hot test). The hot test is preferred.
Technical Paper

CFD Investigation of Exhaust Gas Bypass on Trolley Heating

2020-08-18
2020-28-0006
Most of the automobile and off-road vehicles leave the 100% exhaust gases to atmosphere. The temperature of the exhaust gas ranges from 350-400 deg C and the exit velocity of the gas is about 40-100 m/s based on the outlet pipe design. Dump trucks are used to transport mud, sticky waste garbage and sometime ice from one place to dump yard. The paper will describe the approach of partially use the exhaust gases for truck trolley by heating the trolley surfaces from the walls. CFD software is used to evaluate the exhaust system pressure drop and bypass exhaust flow rate requirements for effective heating on trolley wall. The simulation also helped to design the appropriate baffle position for optimum pressure drop and recirculation. Conjugate heat transfer CFD analysis is carried out to predict the flow & temperature behavior of the exhaust pipe.
Technical Paper

Simulation of Hybrid Packed Desiccant Beds for Dehumidification and Drying

2020-08-18
2020-28-0019
The conventional vapor compression refrigeration cycle based air dryers are used widely for the applications of required pressure dew point temperature up to +2~3°C. However, for the industrial and pneumatic applications, the required pressure dew points are as low as -10°C, -30°C or -50°C and also up to -75°C, which is achieved by the adsorption based packed bed desiccant dryers. This paper presents the results of numerical simulation of hybrid packed desiccant beds under coupled heat and mass transfer during the adsorption and desorption phases under wide operating conditions. The bed containing a homogenous mixture of multiple desiccant types along the vertical axial direction has been investigated. A CFD code has been developed using the finite volume method which models the heat conduction and mass diffusion for these hybrid beds.
Technical Paper

Dynamic Behavior of In-Cylinder Pressure Causing Fatigue Failure of Reed Valves

2020-08-18
2020-28-0031
Numerous studies considering interaction between refrigerant and reed valve motion in positive displacement compressors have been cited in literature. CFD and FEA simulation tools have allowed modeling of fully coupled interaction of fluids and moving parts [1]. The present paper describes a simplified model of a multi-cylinder reciprocating piston compressor and estimation of pressure surge at high compressor speeds. The results show that the delayed discharge valve opening and closing causes surge in pressures due to formation of pressure waves. For the chosen geometry and operating conditions in the present paper, the characteristic travel time of such waves is much shorter (~ 0.2ms) as compared to longer response time of reed valves (> 1ms) owing to stiffness and exhibit delayed opening due to others factors too like stiction effect. These pressure surges may exceed the fatigue limit of reed valves and cause failures.
Standard

Liquid Filter Ratings, Parameters and Tests

2020-08-17
WIP
AIR887D
This SAE Aerospace Information Report (AIR) identifies and explains the meaning of various ratings and terms used to describe the physical characteristics of liquid filter elements. The significance of various filter parameters is discussed. In addition, a number of filter test methods are briefly described. This AIR and the data presented are only applicable where the system liquid wets the filter elements.
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