Piston Crown Research Articles

DigitalAir™ Camless FVVA System - Part 2, Gasoline Engine Performance Opportunities

The paper describes a completely new approach to fully variable valve actuation (FVVA), which allows almost unlimited continuously variable control of intake and exhaust valve opening and closing events, and duration without the use of a camshaft. DigitalAir replaces conventional poppet valves with horizontally actuated valves located directly above the combustion deck of the cylinder head, which open and close a number of slots connecting the cylinder with the intake and exhaust ports, Figure 1. The stroke of the valves to provide the full flow area is approximately 25% of the stroke of the equivalent poppet valve, thus allowing direct electrical actuation with very low power consumption. This design arrangement also avoids the risk of poppet valve to piston collision, or the need for cut-outs in the piston crown, since the valves do not open into the cylinder. The paper will present analytical and experimental data which confirms that the proposed FVVA system can meet the basic performance requirements of modern GDI engines with respect to breathing characteristics across the speed range, throttleless operation at and above idle, opening and closing event optimization, cylinder deactivation, control of residual gas fraction / scavenging and exhaust thermal management. Analytical results were developed using GT-POWER Cycle Simulation and CONVERGE computational fluid dynamics (CFD). Cycle simulation was used to study the system level performance, such as full load capability and transient response, and in particular to quantify the fuel consumption benefits of throttleless operation. CFD was used to better understand the opportunities for in-cylinder charge motion - tumble, swirl and turbulence. JP SCOPE Inc. has been running experimental engines with DigitalAir for several years and has successfully completed performance and durability tests. The mechanical and thermal design of the cylinder head, and the design of the actuator will be covered in Part 1 of this paper [1].

Experimental Investigation on 4-Stroke Low Heat Rejection C.I. Engine with Different Piston Crown Materials

Experimental Investigation on 4-Stroke Low Heat Rejection C.I. Engine with Different Piston Crown Materials

Improving the environmental performance of the internal combustion engine by the use of in-cylinder catalyst

The problems of using the inner surfaces of a combustion chamber as catalytic converters in order to reduce the harmful exhaust emissions were discussed in this paper. The proper choice of the catalyst is one of the most important issues. The interaction between the burned mixture and the catalyst is not limited by the kinetics of the chemical reactions but depends primarily on the flow rate of the reactants to the catalyst surface during combustion. The lifespan of a catalytic layer is determined by the application technique, where plasma spraying is the most popular and most accessible method. However, when it comes to the catalytic coating durability, it is not an efficient option, as ion implantation is indicated shows greater potential in this respect. In this research the coating of aluminum titanium and chromium-nickel have been applied to the engine head and the piston crown. Then the modified catalytic parts were used in a CI combustion engine and the obtained emission results were compared with the reference results. Another set of tests was performed for an SI engine, powered with gasoline and methane, where the piston crown was covered with a thermal layer of zirconium oxide and a catalytic layer of platinum. The beneficial effects of these in-cylinder catalysts on exhaust emissions and the possible problems in the wide spread use of such solutions have been presented.

Performance and CombustionCharacteristics of Thermal Barrier Coated (YSZ) Low Heat Rejection Diesel Engine

Thermal barrier coatings (TBCs) were used to simulate adiabatic engines with the intention not only for reduced in-cylinder heat rejection and thermal fatigue protection of underlying metallic surfaces, but also for possible reduction of engine emissions. In this research work, the main emphasis is placed on investigating the effect of a TBC on the engine fuel consumption with the support of detailed sampling of in-cylinder pressure. Emission measurements of unburned hydrocarbons and carbon monoxide were also conducted in this study. In the present investigation, the piston crown was coated with the YSZ (Y₂O₃&ZrO₂) ceramic material, using a plasma spraying technique. YSZ (Y₂O₃&ZrO₂) was deposited to a thickness of 250 microns over the piston crown. Investigation showed that, Increasing the brake thermal efficiency, NOx emission and O2 and decreasing the specific fuel consumption, CO and HC emissions for Low heat Rejection engine with thermal coated piston compared to the standard engine. The peak cylinder pressures were increased by a magnitude up to 6 bars in the TBC piston engine, in particular at high engine power outputs, though the exhaust gas temperatures were generally lower, indicating good gas expansion in the power stroke which caused the peak cylinder pressure to raise and that impacted on brake thermal efficiency which is increased by 1.4%.

Development of MGE 1.8T combustion system assisted by numerical simulation

This paper describes the CFD assisted combustion system development for a 1.8 L turbo GDI engine which has been developed by SAIC Motor. The combustion system is a direct injected turbocharged system employing centre-mounted multi-hole injectors. The in-cylinder charge motion, fuel injection, air/fuel mixing and combustion processes in the combustion system were evaluated. Proposed intake port options were numerically investigated and compared. Impingement of fuel droplets on piston crown, and wetting on the walls of combustion chamber and the subsequent impacts on mixture formation and oil dilution were investigated by both CFD tool and engine test approaches. Spray targeting was optimised to minimise oil dilution, and multiple fuel injection strategies were investigated to understand its impact on injection, mixture formation and combustion process. The concentrations of pollutants including CO, NOx, HC and soot were simulated. The present simulation results agree well with the measurement data from engine testing, including cylinder gas pressure.

CFD analysis of fluid flow inside a pentroof combustion chamber with different piston shapes

In the present work a study of in-cylinder flow for spark ignition (SI) engine is carried out, for pentroof head piston geometry with four different configurations of the piston crown. The flow pattern is investigated using commercial software package Fluent 6.3 during intake and compression stroke at different engine speeds. The parameters investigated are turbulent kinetic energy (TKE) and tumble ratio. The nature of computed velocity and TKE contours for flat piston combustion chamber is found to be in good agreement with experimental results (Murali et al., 2010). Furthermore, it is found that piston shape significantly affects the velocity and TKE contours of SI engine during the compression stroke. The combustion chamber with trapezoidal piston shows more TKE and tumble ratio when compared to other pistons at 330 crank angle degree, i.e., near TDC during compression, where turbulence is most essential before ignition.

CFD analysis of fluid flow inside a pentroof combustion chamber with different piston shapes

In the present work a study of in-cylinder flow for spark ignition (SI) engine is carried out, for pentroof head piston geometry with four different configurations of the piston crown. The flow pattern is investigated using commercial software package Fluent 6.3 during intake and compression stroke at different engine speeds. The parameters investigated are turbulent kinetic energy (TKE) and tumble ratio. The nature of computed velocity and TKE contours for flat piston combustion chamber is found to be in good agreement with experimental results (Murali et al., 2010). Furthermore, it is found that piston shape significantly affects the velocity and TKE contours of SI engine during the compression stroke. The combustion chamber with trapezoidal piston shows more TKE and tumble ratio when compared to other pistons at 330 crank angle degree, i.e., near TDC during compression, where turbulence is most essential before ignition.

Performance analysis of a biodiesel fuelled diesel engine with the effect of alumina coated piston

Biodiesel is one of the best alternative fuels to Diesel engine among other sources due to having potential to reduce emissions. Biodiesel is a renewable, biodegradable and environment friendly fuel in nature. The advantages of biodiesel are lower exhaust gas emissions and its biodegradability and renewability compared with petroleum-based diesel fuel. The energy of the biodiesel can be released more efficiently with the concept of semi adiabatic (thermal barrier coated piston) engine. The objective of this study is to investigate the performance and emission characteristics of a single cylinder direct injection Diesel engine using 25% biodiesel blend (rubber seed oil methyl ester) as fuel with thermal barrier coated piston. Initially the piston crown was coated with alumina (Al2O3) of thickness of 300 micron (0.3 mm) by plasma coating method. The results revealed that the brake thermal efficiency was increased by 4% and brake specific fuel consumption was decreased by 9% for B25 with coated piston compared to un-coated piston with diesel. The smoke, CO, and HC emissions were also decreased for B25 blend with coated piston compared with the uncoated piton engine. The combustion characteristics such as peak pressure, maximum rate of pressure rise, and heat release rate were increased and the ignition delay was decreased for B25 blend for the coated piston compared with diesel fuel.

Durability analysis of a single cylinder DI diesel engine operating with a non-petroleum fuel

Tyre pyrolysis oil (TPO) derived from pyrolysis of scrap tyres has been proven as a source of heat energy. Earlier investigations indicated that, a blend (JMETPO20) comprising of 20% TPO and 80% Jatropha methyl ester (JME) was found to be the optimum blend, when tested in a diesel engine. A comparative study reported in this paper is aimed to examine the durability issues of a direct injection diesel engine run on the JMETPO20 blend and diesel. For this purpose, the engine operated with the JMETPO20 blend and diesel was run for 100h, which consist of 14 test cycles of 7h each as per the IS 10000 standards. Visual examination of the vital parts of the engine components such as cylinder head, piston crown, and nozzle injector tip, etc. was also carried out to find the carbon deposit after the durability test. After the durability test, several tribological characteristics of the used lubricating oil were evaluated after every 25h of engine operation in order to analyze the consequence of fuel chemistry on the life of the lubricating oil. Measurement of different metal debris concentrations present in the lubricating oil samples drawn from the JMETPO20 blend and diesel operated engine was carried out by the atomic absorption spectroscopy.

Growth and characterization of deposits in the combustion chamber of a diesel engine fueled with B50 and Indonesian biodiesel fuel (IBF)

Although used since 1893, biodiesel still faces problems that must be overcome before it can fully replace petroleum diesel. Existing literature shows that continuous use of biodiesel could lead to higher growth of deposits on critical engine components, contributing to lots of problems that could ultimately decrease engine performance. In this context, endurance tests were performed to compare the impacts of B50 and Indonesian biodiesel fuel (IBF: diesel fuel containing 10% palm oil biodiesel) on engine durability. More specifically, deposits growth as well as deposits structure and composition in response to the application of the above-mentioned fuel blends were investigated over 200 h. The results revealed that B50 produced relatively larger amounts of deposits especially on the valves and injector tip while also increased the risk of ring sticking. In addition, the structure and the elemental composition of the deposits formed on engine important components, i.e., injector tips, piston crown, intake/exhaust valves, cylinder head, and piston grooves when B50 was used were quite different compared with the IBF. Overall, more deposits formation was observed by increasing biodiesel inclusion rate while deposits tended to be wet and brittle as well.

Experimental observations of engine piston damage induced by knocking combustion

Abnormal combustion leads to a significant increase in combustion speed, pressure and temperature at the surfaces enclosing the combustion chamber. Severe and lasting knock or pre-ignition can permanently damage and, in many cases, destroy engine pistons, due to very high and localised thermomechanical stresses. The deleterious effects of abnormal combustions have led car manufacturers to set extremely precautionary thresholds in spark advance calibration (in terms of temperatures and pressures) of turbocharged spark ignition direct injection engines, often limiting engine performance and efficiency. Since the mechanisms of piston damage due to abnormal combustion are not currently fully understood, the aim of this study was to characterise its effects on Al forged pistons. The more suitable characterisation techniques were evaluated. The results highlighted that roughness measurements, as well as visual, optical and scanning microscopy analyses on specific zones of the top land and piston crown are useful techniques to qualitatively relate piston damage to combustion regime. Moreover, a significant quantitative relationship was observed between the MAPO (Maximum Amplitude Pressure Oscillations) index and residual piston hardness.

Investigation of Performance and Emission Characteristics of VCR Engine by Using Ceramic Coating on the Piston Crown with Using Methanol Fuel

The world faces the energy demand, exaggerated crude rates and reduce of fuel resources. Methanol has been considered as an alternate fuel. . The current study takes out an experiment of using methanol in VCR engine. They are blended with diesel at various mixing ratios. The results of methyl alcohol works in engine were checked in an exceedingly single cylinder, direct injection, water cooled and high speed VCR internal combustion engine at varied engine load with constant engine speed of 1500rpm conjointly we tend to mistreatment the limit coated piston with MgO-ZrO2 and Al2O3-13%TiO2 to investigation on performance and emission characteristics. The limit coating materials has low thermal conduction, low thermal expansion and high young’s modules. The influences of blends on CO, CO2, HC, NOX were investigated by emission tests. The brake thermal efficiency of mix M20 was found on top of diesel. The emissions of smoke, hydro carbon and chemical element oxides of methyl alcohol blends were on top of that of diesel. However the CO2 emission is higher once we compare with diesel.

Effect of injection timing on combustion and soot formation in a direct injection spark ignition engine fueled with butanol

Ever tighter restrictions on pollutant emissions, energy security and a continuous drive for improving fuel economy have extended the range of application for direct injection in spark ignition engines and promoted the use of alternative fuels. Direct injection features higher soot formation compared to external mixture preparation, and therefore, intensive research is performed for understanding the processes related to this pollutant category. This study looked into the effect of injection timing in a wall-guided direct injection spark ignition engine when gasoline was completely replaced with n-butanol. Thermodynamic measurements were coupled with optical investigations that provided improved insight into local distribution of diffusive flames during late combustion stages. These data were correlated with exhaust gas measurements of CO, HC and NOx, as well as opacity. The optimum setting for injection timing was found to be a compromise between intake airflow velocity and piston positioning that influenced wall impingement. Late injection resulted in reduced soot but higher HC emissions, as well as lower performance compared to the optimum point. Early fuel delivery had roughly the same effect on indicated mean effective pressure and stability, with the downside of increased opacity. These observations were detailed with data obtained through cycle-resolved imaging that showed different integral luminosities with respect to injection phasing and confirmed that fuel impingement on the piston crown is the main factor of influence for soot formation. Ultraviolet–visible spectroscopy in the late combustion phase was also applied in repetitive mode in order to provide better insight into cyclic variability of the emission intensity in the range specific for carbonaceous structures.

Thermal Effect on the Automobile Piston: A Review

Background/Objectives: Mechanical and thermal properties of aluminum-based piston alloys are mainly depend on the heat treatment. Conventional heat treatment techniques are also not resulted to that level where it can be used for piston of downsized engine. Methods/Statistical Analysis: Around 30 papers were reviewed to understand the thermal effects and consequences on the Al Si piston alloy. Findings: From the literature it can be understood that two-step solution treatment of the Al Si alloy resulted the good mechanical properties then the single step solution treatment. Heat treatment at 540°C for 8 h and aging at 190°C for 8 h is correctly choice to achieve optimum mechanical properties by heat treatment. To calculate the temperature effect and heat transfer to the engine piston crown, the spatial and time averaged combustion side boundary condition is a most favorable and suitable treatment method within engineering approximations. For temperature and thermal stress distributions for a coated surface piston crown, the coating surface temperature increased with coating thickness by decreasing rate and the best results are at 1 mm coating. Application/Improvements: The coated piston has low thermal conductivity then the uncoated piston.

EFFECT OF INJECTION TIMING IN LHR DIESEL ENGINE USING SIMAROUBA BIODIESEL BLENDS AS FUEL

Experiments were conducted on a single cylinder air cooled Conventional Engine (CE) and Low Heat Rejection (LHR) diesel engine using Simarouba Biodiesel Blends (SBD10, SBD20 and SBD30) as substitute fuel. Piston crown is coated with 300 microns of Partially Stabilized Zirconia (PSZ) to operate as LHR engine. Conventional Engine was run with diesel andbiodiesel blends at 200 bar injection pressure and injection timing of 23 o before top dead centre (btdc) to get base line data at varying load conditions (0, 25%, 50%. 75% and 100% of full load). LHR engine was made to run with blends at three injection timings of 23 o , 20 o (retarded) and 26 o (advanced) btdc respectively. The performance parameters such as Brake Thermal Efficiency (BTE), Brake Specific Fuel Consumption (BSFC), and Exhaust Gas Temperature (EGT) were considered, emissions (CO2, HC, NOXand Filter Smoke Number-FSN) were recorded for both engines. The results showed that LHR engine with injection timing of 20 o btdc,significantly reduces emissions (in particular NOX) for all blends compared to conventional diesel engine with slight loss in BTE.LHR engine with advanced injection timing showedenhanced BTE, reduced CO and HC emissions with NOxincreasing rapidly.

피스톤 크라운용 단강에 인코넬 718 용접재료로 용접된 용접부의 특성 평가

피스톤 크라운용 단강에 인코넬 718 용접재료로 용접된 용접부의 특성 평가

Thermal analysis of holes created on ceramic coating for diesel engine piston

This paper deals with the steady state thermal analysis of diesel engine piston coated with ceramic coating having holes on its surface. Temperature distribution on the piston's top surface and substrate surface is investigated by using finite element based software called Ansys. Yttria-stabilized Zirconia is used as ceramic coating applied on Al–Si piston crown. The 2 thickness of ceramic top coating is about 0.4mm and for NiCrAl bond coat it is taken to be 0.1mm. Temperature distribution is investigated by choosing various radiuses of holes created on the ceramic coating surface about 1.5mm, 2mm and 2.5mm. From the results it is observed that the top surface (coated surface) temperature is increasing with increase the radius of the holes. Maximum temperature of coated surface is occurs for highest hole radius of about 2.5mm. Compared with coating have no hole, a significant increase in the pistons top surface temperature occurs with coating having holes. Although, the substrate temperature is decreasing with increase the radius of the holes.

EXPERIMENTAL INVESTIGATION ON PERFORMANCE OF SINGLE CYLINDER FOUR STROKE SPARK IGNITION ENGINE WITH MODIFICATION OF PISTON CROWN

A decent swirl advances the quick burning and enhances the efficiency for engine which is preferably running at low speeds in order to have low mechanical losses and empowering good combustion efficiency. Subsequently to create high turbulence preceding burning inside the cylinder, swirl prompted by the bay channel inside the cylinder head will be useful. The automobile vehicles still satisfying demands for high performance, requires immense efforts to create new engine ideas and deliver less emission. Swirl is used in SI engine to speed up the combustion process in four stroke engines It increases turbulence and accelerates chemical action by intimating mixing of fuel and oxygen there by weak mixtures can be burnt effectively. In Petrol engine, swirl can increase the rate of fuel-air mixing, reducing the combustion duration for re-entrant chambers at retarded injection timings. Swirl interaction with compression induced squish flow increases turbulence levels in the combustion bowl, promoting mixing. In order to achieve the swirl the piston crown of the conventional petrol engine was suitably modified by forming different shaped grooves on it. This facilitates increased intensity of the swirl for proper mixing of air fuel and to examine their effects on the performance of this engine fuelled with petrol and its blends with ethanol. In the present work Experiment was carried out with unmodified and modified piston with different shapes without much changing compression ratio comparative results shows that better combustion in gasoline engine was obtained with single groove hemispherical piston. Brake thermal efficiency increased by 1.39% and Brake specific fuel consumption reduced by 3% for E10P90 blend compared to unmodified piston

A novel method for correction of temporally- and spatially-variant optical distortion in planar particle image velocimetry

In-cylinder flow measurements are necessary to gain a fundamental understanding of swirl-supported, light-duty Diesel engine processes for high thermal efficiency and low emissions. Planar particle image velocimetry (PIV) can be used for non-intrusive, in situ measurement of swirl-plane velocity fields through a transparent piston. In order to keep the flow unchanged from all-metal engine operation, the geometry of the transparent piston must adapt the production-intent metal piston geometry. As a result, a temporally- and spatially-variant optical distortion is introduced to the particle images. To ensure reliable measurement of particle displacements, this work documents a systematic exploration of optical distortion quantification and a hybrid back-projection procedure that combines ray-tracing-based geometric and in situ manual back-projection approaches.The proposed hybrid back-projection method for the first time provides a time-efficient and robust way to process planar PIV measurements conducted in an optical research engine with temporally- and spatially-varying optical distortion. This method is based upon geometric ray tracing and serves as a universal tool for the correction of optical distortion with an arbitrary but axisymmetric piston crown window geometry. Analytical analysis demonstrates that the ignorance of optical distortion change during the PIV laser temporal interval may induce a significant error in instantaneous velocity measurements. With the proposed digital dewarping method, this piston-motion-induced error can be eliminated. Uncertainty analysis with simulated particle images provides guidance on whether to back-project particle images or back-project velocity fields in order to minimize dewarping-induced uncertainties. The optimal implementation is piston-geometry-dependent. For regions with significant change in nominal magnification factor, it is recommended to apply the proposed back-projection approach to particle images prior to PIV interrogation. For regions with significant dewarping-induced particle elongation (), it is recommended to apply the proposed dewarping method to the vector fields resulting from PIV interrogation of raw particle image pairs.

Thermal Analysis of Ceramic Coated Aluminum Alloy Piston using Finite Element Method

The objective of this paper is to establish the temperature distributions in plasma sprayed Yttria Stabilized Zirconia (YSZ) and magnesia stabilized zirconia (MgZrO 3 ) thermal barrier coating on an aluminum alloy piston crown to raise the potential of a diesel engine. The influence of ceramic coating thickness on temperature variations are studied by finite element method using ANSYS. The temperature distribution analyses were conducted for the ceramic coating thickness of 0.3 mm over the piston crown surface. The results of the piston coated with two different coatings were analyzed. It is observed that, the peak exterior surface temperature of the ceramic piston with the material MgZrO 3 is increased by 32% and 20% for the piston coated with yttria stabilized zirconia compared with conventional aluminum alloy piston. It is concluded that the substrate temperature of the piston coated with MgZrO 3 and yttria stabilized zirconia is reduced by 25% and 17% compared with uncoated aluminum alloy piston. The lower substrate surface temperature by coating results in improved heat to work conversion efficiency of the engine.