High-performance Internal Combustion Engines Research Articles

Analysis of the tribological behaviour of the lubricated contacts of a connecting rod equipped with a direct pin oiling gallery

This paper describes a methodology for identifying a suitable design of a Direct-Pin-Oiling (DPO) gallery, drilled through the conrod shank of a high-performance internal combustion engine, to directly supply pressurized lubricant to the piston pin/small-end interface. Initially, a multibody elastohydrodynamic model is set up to analyse the tribological behaviour of conrod bearings, when considering a standard configuration employing a passive lubricating hole drilled on the top of the small-end. Then, a preliminary DPO gallery is introduced to examine how it affects the oil flows at lubricated interfaces and their tribological behaviour. The numerical results and parallel experimental evidence underline the need to modify the initial configuration of the DPO gallery and a more performing gallery design is proposed.

Numerical modelling of the cavitation damage in the conrod big end bearing of a high-performance internal combustion engine

In this contribution a complementarity formulation for the solution of the elastohydrodynamic problem in the presence of cavitation is employed to investigate the tribological behaviour of the conrod big end bearing in a high-performance internal combustion engine. The continuous effort towards higher engine efficiencies, poses new challenges related to the increased specific loads to which engine components are subjected. In particular, the connecting rod big end bearing is subjected to both high loads and high relative velocity of the mating surfaces. Therefore, its tribological behaviour plays a crucial role. In fact, on one side, possible asperity contact pressures can produce wear of the interested components, and on the other side, a parallel possible cavitation of the lubricant can additionally damage the mating interfaces. Unfortunately for quantifying the cavitation damage, a universally established theory does not exist, even if it is well accepted that it is related to the sudden rapid implosion of the vapour bubbles near the surface. The precise investigation of this damage mechanism is usually neglected in big end bearing analysis since the implosion of the bubbles is difficult to quantify and it is not a standard output of any commercial software. Thus, in this work, a quantitative index previously proposed is reviewed and adopted to quantify the cavitation damage in a connecting rod big end bearing.

Development of an experimental/numerical validation methodology for the design of exhaust manifolds of high performance internal combustion engines

Several typical failure modes in the exhaust manifold of an internal combustion engine are commented on. In particular, thermal loading and the related thermal fatigue damage mechanism are addressed. The component under investigation is a cast exhaust manifold including the turbine involute. Finite Element simulations are performed, and a numerical methodology is presented to interpret and understand the observed failures, with the aim of developing a useful tool to virtually validate the component, before the manufacturing phase. The Finite Element analysis closely mimics the experimental validation procedure that considers several heating and rapid cooling cycles to simulate typical engine operating conditions. A static mechanical characterization at high temperatures of the materials involved is carried out, aimed at identifying a suitable alloy and its mechanical characteristics useful for feeding the numerical models. The developed design methodology proposes a damage criterion for thermal fatigue investigation, considering the elastoplastic behaviour of the material when subjected to high temperature cycles. In particular, the accumulated equivalent plastic strain range for a single thermal cycle (ΔPEEQ) is used, following the Ferrari expertise. The methodology appears to be well correlated with the experimental evidence, thus limiting the number of tests necessary for the approval of the component.

Correlation between heat transfer and flow in an internal combustion engine evaluated with a MEMS sensor

Understanding heat transfer is important for developing high-performance internal combustion engines, but heat transfer mechanisms have not yet been elucidated. The objective of this study is to clarify the correlation between flow and heat transfer in an engine. Local instantaneous heat flux and advection speed adjacent to a wall were measured using a resistance-type three-point heat flux sensor to achieve this purpose. Furthermore, local instantaneous Nusselt and Reynolds numbers were calculated based on the measured heat flux and the advection speed using two characteristic lengths: (1) bore diameter and (2) penetration depth. Consequently, it was found that the ensemble-averaged Nusselt numbers varied exponentially as a function of the ensemble-averaged Reynolds numbers in both models, and good correlation equations could be derived. The penetration-depth model reproduced the experimental values more precisely. On the other hand, the Reynolds number index of the bore-diameter model corresponds with the heat transfer on the rear wall of a cylinder installed in a flow. This suggests an analogy between the engine and rear wall of a cylinder. Additionally, the impacts of each heat transfer factor were evaluated. As a result, it was found that a dominant factor until the heat flux peak is the temperature difference between the gas and wall. However, its effect becomes small after the heat flux peak, and it was found that the density and advection speed mainly affect the heat flux decrease.

A laser-absorption sensor for in situ detection of biofuel blend vapor in engine intakes

A novel, mid-infrared laser-absorption sensor was developed for measurements of biofuel blend (E85) vapor in the intake runner of a single-cylinder internal combustion engine. The sensor used two mid-infrared interband cascade lasers to target a region of strong E85 absorbance near 3.35 µm. The lasers were co-aligned and fiber-coupled into the engine, and a two-color, online-offline differential absorption strategy was used to provide sensitive measurements of E85 vapor mole fraction and reject interference due to beam-steering and fuel droplet spray. An intensity-modulation spectroscopy (IMS) sensing scheme was employed to reject low-frequency additive noise and allow for frequency-domain multiplexing of the two lasers. High-resolution E85 absorption cross-section measurements were conducted in a static cell at a range of intake-relevant conditions. Validation experiments were performed in a laboratory setting to demonstrate sensor accuracy and noise rejection capability. The sensor was deployed on a single-cylinder development engine during dynamometer testing to provide time-resolved E85 vapor mole fraction measurements at a measurement rate of 40 kS/s, which corresponds to one measurement per crank angle degree at 6700 rpm. Time-resolved and average sensor measurements provide key performance insights for the development of intake systems in high-performance internal combustion engines.

Influence of the thermal deformation on the lubricating performance of the piston-gudgeon pin interface in an internal combustion engine

This contribution describes a methodology to evaluate the influence of bellmouth profiles on the elastohydrodynamic behaviour of the contact interface between the gudgeon pin and the piston of a high-performance internal combustion engine. First, a thermo-mechanical simulation is performed to evaluate the piston bosses thermal strains. Consequently, a Multibody elastohydrodynamic model is set up to evaluate the tribological behaviour of this lubricated interface considering a perfectly cylindrical shape of the piston bosses and their thermal deformation. Then, a preliminary bellmouth profile is adopted and a second Multibody model is performed. Nevertheless, the results, together with issues encountered analysing some tested pistons, suggest that modifications of piston bosses have to be introduced. Finally, an optimised bellmouth geometry is proposed and analysed.

The Renewable Hydrogen–Methane (RHYME) Transportation Fuel: A Practical First Step in the Realization of the Hydrogen Economy

The permanent introduction of green hydrogen into the energy economy would require that a discriminating selection be made of its use in the sectors where its value is optimal in terms of relative cost and life cycle reduction in carbon dioxide emissions. Consequently, hydrogen can be used as an energy storage medium when intermittent wind and solar power exceed certain penetration in the grid, likely above 40%, and in road transportation right away, to begin displacing gasoline and diesel fuels. To this end, the proposed approach is to utilize current technologies represented by PHEV in light-duty and HEV in heavy-duty vehicles, where a high-performance internal combustion engine is used with a fuel comprised of 15–20% green hydrogen and 85–89% green methane depending on vehicle type. This fuel, designated as RHYME, takes advantage of the best attributes of hydrogen and methane, results in lower life cycle carbon dioxide emissions than BEVs or FCEVs and offers a cost-effective and pragmatic approach, both locally as well as globally, in establishing hydrogen as part of the energy economy over the next ten to thirty years.

Desulfurization Behavior of Incoloy\xae 825 Superalloy by CaO-Al2O3-MgO-TiO2 Slag

Ni-based superalloy, which has excellent high-temperature strength and corrosion resistance, is mainly used in aviation materials, high-performance internal combustion engines, and turbines for thermal and nuclear power generation. For this reason, refining the impurities in Ni-based superalloys is a very important technical task. Nevertheless, the original technology for the melting and refining of Ni-based superalloys is still insufficient. Therefore, in this study, the effect of the CaO-Al2O3-MgO-TiO2 slag on the removal efficiency of an impurity element sulfur in Incoloy® 825 superalloy, one of the representative Ni-based superalloys, was investigated. The desulfurization behavior according to the change of TiO2 content and CaO/Al2O3 (=C/A, basicity) ratio as experimental variables was observed at 1773 K (1500 °C). Although the TiO2 content in the slag increases to 15 mass pct, the mass transfer coefficient of sulfur in molten alloy showed a constant value. Alternatively, under the condition of C/A > 1.0 of slag, the mass transfer coefficient of sulfur showed a constant value, whereas under the condition of C/A < 1.0, the mass transfer coefficient of sulfur greatly decreased as CaO decreased. Hence, in the desulfurization of Incoloy® 825 superalloy using the CaO-Al2O3-MgO-TiO2 slag, the TiO2 content in the slag does not have a considerable effect on the desulfurization rate and desulfurization mechanism (metal phase mass transfer controlled regime), but the basicity of the slag has a significant effect on desulfurization mechanism. When the slag basicity decreases below the critical level, i.e., C/A < 1.0, which is corresponding to sulfur distribution ratio, Ls < 200, it was confirmed that the desulfurization mechanism shifts from the metal phase mass transfer-controlled regime to the slag phase mass transfer-controlled regime due to the variation in the physicochemical properties of the slag such as viscosity and sulfide capacity. In addition, the different desulfurization rates between steel and Ni alloy melts were discussed by employing the diffusivity of sulfur in both systems.

Dynamic behaviour modelling of an internal combustion engine water pump transmission belt drive

Belt drives are commonly used in various types of transmissions to link two or more rotating shafts. In order to transmit the motion, an effective grip on the pulley has to be set by imposing a pre-load on the belt. Moreover, the dynamics of the system is strongly affected not only by the geometrical and inertial properties but also by the imposed belt tension force as a functional parameter affecting the vibration characteristics. In the present work, it is presented an integrated methodology, experimental and numerical, to determine the dynamic behaviour of a water pump drive in a high-performance internal combustion engine.

A Novel Electromechanical Solution for Cam-Switching in High Performance Internal Combustion Engines

Abstract The variation of the valve lift is a fairly common strategy currently adopted in several in-service internal combustion engines to optimize their performance depending on the operating conditions of the vehicle. The most critical aspect to consider during the conceptual design phase of a cam switch system is the extremely narrow window of opportunity to perform the cam change, which duration is defined by the time during which the corresponding valve lift is null. To meet this requirement and ensure safe, repeatable movements, a novel architecture based on the combination of a new electromechanical actuator and its dedicated control system is presented. The architecture is at first introduced with reference to the numerous examples available in the literature, and hence mathematically described. The dynamic model of the system derived from the presented equation is then used to study the performance of the presented solution and define its control strategy. Results are finally presented and discussed.

Friction Reduction in Unidirectional Lubricated Sliding Due to Disc Surface Texturing

Surface texturing is an option of surface engineering resulting in reduction of friction due to the creation of isolated dimples or grooves on sliding surfaces. The purpose of this work is to find the effect of the groove bottom profiles on the reduction of the friction force. Investigations were conducted using an Optimol SRV5 tribotester equipped with a pin-on-disc module. A disc made of 42CrMo4 steel, with a 100 mm diameter acted as a sample. A counter-sample was made of the same material, however, its diameter was 20 mm. The sliding conditions were selected to be similar to those of a sliding crankpin bearing pad operating in a high-performance internal combustion engine. Surface texturing was found to be beneficial for a reduction in the friction coefficient up to 55% in comparison to the untextured disc. Tribological performances of discs with spiral groove patterns were better than those with a radial layout. In most cases the convergent profile of the groove bottom was superior to the dam shape.

A Finite Element Numerical Methodology for the Fatigue Analysis of Cylinder Liners of a High Performance Internal Combustion Engine

In this paper a numerical methodology is proposed, which aims at predicting the fatigue behaviour of engine cylinder liners in an eight-cylinder V-type four-stroke turbocharged engine. A preliminary kinematic and dynamic study of the crank mechanism is fulfilled in order to properly identify the load cycle that involves the cylinder liner. Finite Element analyses, both thermal and thermo-mechanical, are performed to evaluate the stress and the strain of the component. In particular, non-linear models are developed to mimic the piston-liner interaction when subjected to different loading conditions. A simplified approach is proposed in order to reduce the computational effort of the simulations. FEM results are then processed employing the multiaxial Dang Van fatigue criterion.

An assessment of gas power leakage and frictional losses from the top compression ring of internal combustion engines

A multi-physics integrated analysis of piston top compression ring of a high-performance internal combustion engines is presented. The effects of transient ring elastodynamics, thermal gas flow through piston crevices upon chamber leakage pressure and parasitic frictional losses are investigated. The multi-physics analysis comprises integrated flexible ring dynamics, ring-liner thermo-mixed hydrodynamics and gas blow-by, an approach not hitherto reported in literature. The predictions show close conformance to frictional measurements under engine motored dynamometric conditions. It is shown that power losses due to gas leakage can be as much as 6 times larger than frictional losses, which are usually considered as the main sources of inefficiency.

The combined effect of surface texturing and DLC coating on the functional properties of internal combustion engines

A reduction in frictional loss is an important aspect of efficiency in high-performance internal combustion engines. This can be achieved by the well-designed surface texturing of the cylinder bore, which can reduce friction at the ring/bore interface. In this work, dimples were created using plastic deformation on the cylinder surfaces of high-performance motorcycle engines. Prior to texturing, these cylinders had Nikasil coating. One cylinder was subjected to the deposition of DLC coating and then surface texturing. The results of the functional performance of internal combustion engines with textured cylinder surfaces were compared to untextured ones. The engine performance was analysed in terms of maximum power and maximum torque output. The results showed that cylinder surface texturing improved the functional properties of internal combustion engines. The maximum power increased by up to 5.8%. Best performance was achieved for internal combustion engines with textured cylinders and DLC coating. Such surface modification allows the powering of the motorbike with higher maximum speed and provides better vehicle dynamics at high speeds.

Assessment of friction from compression ring conjunction of a high-performance internal combustion engine: A combined numerical and experimental study

The paper presents direct measurement of in-cylinder friction from a single cylinder motocross race engine under motored conditions and compares the same with a new analytical predictive method. These conditions are encountered in piston–cylinder system with the application of cylinder deactivation (CDA) technology, which is a growing trend. The analytical method takes into account the various regions within instantaneous contact of compression ring–cylinder liner, including lubricant film rupture, cavitation zone and the subsequent lubricant film reformation. The analysis also includes the effect of boundary friction and lubricant rheology. The predictions and direct measurements of cyclic friction show good agreement and indicate dominance of viscous friction under the investigated engine running conditions. In particular, it is shown that the compression ring contribution to in-cycle friction is most pronounced in the region of high cylinder pressures because of combined Poiseuille friction and some boundary solid interactions. The combined experimental-analytical approach has not hitherto been reported in literature.

DESENVOLVIMENTO DE NOVOS AÇOS VÁLVULA PARA APLICAÇÃO EM MOTORES DE ALTO DESEMPENHO

UNS N07751 and UNS N07080 alloys are commonly applied for automotive valves production for high performance internal combustion engines. These alloys present high hot resistance to mechanical strength, oxidation, corrosion, creep and microstructural stability. However, these alloys presents low wear resistance and high cost due to the high nickel contents. In this work it is presented the development of two new Ni-based alloys for application in high performance automotive valve as an alternative to the alloys UNS N07751 and UNS N07080. The new developed alloys are based on a high nickel-chromium austenitic matrix with dispersion of γ’ and γ’’ phases and containing different NbC contents. Due to the nickel content reduction in the developed alloys in comparison with these actually used alloys, the new alloys present an economical advantage for substitution of UNS N07751 and UNS N0780 alloys

Experimental investigation of the fluid dynamic efficiency of a high performance multi-valve internal combustion engine during the intake phase: Influence of valve-valve interference phenomena

The purpose of the present work is the analysis of the fluid dynamic behavior of a high performance internal combustion engine during the intake phase. In particular, a four-valve spark-ignition engine has been characterized at the steady flow rig. Dimensionless discharge coefficients have been used to define the global fluid dynamic efficiency of the intake system, while the Laser Doppler Anemometry (LDA) technique has been employed to evaluate the mean flow in the valve curtain area and to characterise the interference phenomena between the two intake valves. The investigation has shown the significant influence of the valve lift on the volumetric efficiency of the intake apparatus. Moreover, the experimental analysis has highlighted that the valve-valve interference phenomena have a relevant impact on the head breathability, on the flow development within the combustion chamber and on the velocity standard deviations.

A century of high performance engine testing

The past century has seen significant developments in the high performance internal combustion engine. These changes were driven in the first 50 years by accelerated technology due to two World Wars. A study of the engines in the period 1914–1918 and 1939 to 1944 is interesting in so much as many of the current designs of modern engines were in place. The materials and most importantly the computing power were simply not available. In 1960, a four cylinders normally aspirated race engine produced less than 100 BHP (74 kW) per liter capacity; today this is the norm for standard production car engines. A major thrust in the development of high performance engines came with the introduction of Formula 1 racing, as we understand it today in the early 1960’s when the engine capacity was reduced to 1.5 liters and the engines were normally aspirated. This lead to the onset of high revving engines than ran through to 12,000 rev/min, but still retained a flat BMEP (brake mean effective pressure) curve in excess of 1.4 MPa peak and at least 1.1 MPa from 4,500 rev/min through to 12,000 rev/min. In the course of some 45 years power per liter has risen from 100 BHP to 300 BHP (74–220 kW) and dynamometers and specialist instrument design has kept pace with this rise in efficiency. The paper will follow these trends and discuss in some detail the instrumentation that was available to early engineers and follow progress through today, culminating in low inertia dynamometers that are capable of continuous running at 30,000 rev/min and absorbing 2,500 BHP (1,800 kW).

Load-free sliding overplate for highly loaded big end bearings

Lead has always been an important metal in plain bearing technology. Completely lead-free solutions for high-end engine applications are still not considered to be technically achievable. Therefore, the European End of Life Directive (2000/53/EC), which took effect on 1 July 2003, lists copper-based lead/bronze bearings as an exception. The bearing group of Federal-Mogul has now announced its exit from the lead industry and addresses the issue layer by layer. A recently introduced adaptive bearing offers a lead-free overplate for high-performance internal combustion engine applications. This new bearing changes its technical characteristics during the running-in phase.

Some considerations concerning lubrication in high‐performance internal combustion engines

AbstractThe increasing rotational speeds and the weight reduction of high‐performance internal combustion engines are accompanied by problems of lubrication, heat transfer, and vibration that are mostly negligible in medium‐ and low‐performance engines. To deal with such phenomena under demanding operating conditions necessitates a specific design. The dynamics of the power system between crankshaft and related sub‐components, e. g., bending and torsional vibrations of the connecting rod, ovalisation of the head and eye of the connecting rod, and vibrations of thin cylinder liners, are critical for the lubrication system in general, and for oil film pressure fields in particular. In some cases, no information on these features has existed until now, so no quantification of the variables involved has been possible. Over the last few years a systematic investigation has been performed to take into account the critical points and their fundamental importance in the design of such engines.The present paper considers some of the phenomena related to lubrication in high‐performance engines. The need is highlighted for further investigations using computational and experimental methodologies.