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Spray formation and break-up are crucial phenomena for mixture formation inside diesel engines, both for combustion control and pollutant formation. Since the emission restrictions have become more and more severe in the last years, many studies have been conducted in order to improve diesel injection. Numerical simulations have proven to be reliable in producing results in a faster and cheaper way than experimental measures. The recent great progresses in computer science, then, have allowed to reach great accuracy in the simulations. In this work, a novel methodology based on Boltzmanns Kinetic Theory is applied to diesel injection. Lattice Boltzmann BGK (LBGK) provides and alternative method for solving fluid-dynamic problems and allows even superior accuracy as compared to conventional CFD. The multiphase approach used in this paper to study spray formation and primary is based on the works by Shan and Chen and their successive modifications.

In the recent past, an always increasing attention have been addressed to the definition and optimization of the HVAC system for fully electric vehicles. The new vehicle layouts and the different operating temperatures of the whole powertrain ask for a re-thinking of the HVAC concept for the modern architectures. In this ballpark, the possibility to deal with a compact and efficient apparatus without moving parts and capable to provide both cold and hot fluxes is really attractive. This is the reason why this work deals with the design and optimization of a vortex tube for automotive applications. Such a component, in fact, is capable to separate a highly swirled flow in two different branches, a cold one and a hot one (one inlet - two outlets). The balance in between the two obtained mass flows can be simply realized via ruling the backpressure at the hot side, with keeping constant the cold one.

Turbulence modeling is a key aspect for the accurate simulation of ICE related fluid flow phenomena. RANS-based turbulence closures are still the preferred modeling framework among industrial users, mainly because they are robust, not much demanding in terms of computational resources and capable to extract ensemble-averaged information on a complete engine cycle without the need for multiple cycles simulation. On the other hand, LES-like approaches are gaining popularity in recent years due to their inherent scale-resolving nature, which allows the detailed modeling of unsteady flow features such as cycle-to-cycle variations in a DI engine. An LES requires however a large number of simulated engine cycles to extract reliable flow statistics, which coupled to the higher spatial and temporal resolution compared to RANS still poses some limits to a wider application of such methodology on realistic engine geometries.

The interest in Unsteady Reynolds-Averaged Navier-Stokes (URANS)/Large Eddy Simulation (LES) hybrids, for the simulation of turbulent flows in Internal Combustion Engines (ICE), is consistently growing. An increasing number of applications can be found in the specialized literature for the past few years, including both seamless and zonal hybrid formulations. Following this trend, we have already developed a Detached Eddy Simulation (DES)-based zonal modeling technique, which was found to have adequate scale-resolving capabilities in several engine-like reference tests. In the present article we further extend our study by evaluating the effects of the underlying turbulence model and of the grid quality/morphology on the scale-resolved part of the flow. For that purpose, we consider DES formulations based on an enhanced version of the k-g URANS model and on the URANS form of the popular RNG k-ε model.

In this paper, a multiphase Lattice Boltzmann approach is adopted to directly simulate flow conditions that lead to the inception of cavitation in an orifice. Different values of fluid surface tension are considered, which play a dramatic role in the evolution of vapour cavity, as well as different inlet velocities at the computational domain boundary. The results of the flow simulations in terms of density and velocity magnitude fields are examined, with special focus on the components of the stress tensor inside the cavitating region: a comparison with cavitation inception criteria known form literature is proposed, highlighting the good agreement between our direct numerical simulations and theoretical predictions.

The effects of the internal geometry of catalytic converter channels on flow characteristics; exhaust backpressure and overall conversion efficiency have been investigated by means of both numerical simulations and experimental investigations. The numerical work has been carried out by means of a micro scale numerical tool specifically tailored for flow characteristics within converter channels. The results are discussed with aid of flow distribution patterns within the single cell and backpressure figures along the catalyst channel. The results of the numerical investigation provide information about the most efficient channel shapes. An experimental validation of the simulated results has been carried out with a production 3.6 liter, 6-cylinder engine on a dynamic test bench. Both modal and bag emission data have been measured during the FTP-Cycle.

In the last three decades, with the growing concern on environmental impact and with the market demand for safety and lower fuel consumption, aerodynamic development has become a standard part of the automobile design area and it is easy to foresee that this is going to happen very fast also for motorcycles. Furthermore, a new concept of motorcycle called maxiscooter has successfully entered the European market. Maxiscooters represent an evolution of the small size engine scooters (from 50 to 125 cc) that were created in the 50s for city use. This category of motorcycles is aimed to a wealthy and more adult market, which needs a pleasant design, riding comfort and stability at higher speed. On the other hand, such vehicles for city use are passing a critical moment in terms of development of the engines, because of the stricter limits imposed by the environmental regulations and for the consequent and significant effects on performance.

The aerodynamic evaluation that influences the shape of new vehicles is only one of the many different aspects that must be carefully considered in a vehicle design program. However, the aerodynamic development enters from the earliest stages, in the shape optimization program, and continues up to full production level, until the detail is optimized. As wind tunnel measurements continue to be the most common and extensively used approach, the rapid evolution of computers in terms of electronic data processing and storage and the progress achieved in computational fluid dynamics (CFD), suggest its utilization in supporting and reducing experimental tests.

A two-equation Zonal-DES (ZDES) approach has been recently proposed by the authors as a suitable hybrid URANS/LES turbulence modeling alternative for Internal Combustion Engine flows. This approach is conceptually simple, as it is all based on a single URANS-like framework and the user is only required to explicitly mark which parts of the domain will be simulated in URANS, DES or LES mode. The ZDES rationale was initially developed for external aerodynamics applications, where the flow is statistically steady and the transition between zones of different types usually happens in the URANS-to-DES or URANS-to-LES direction. The same “one-way” transition process has been found to be fairly efficient also in steady-state internal flows with engine-like characteristics, such as abrupt expansions or intake ports with fixed valve position.

An engine head for microcar applications has been analysed and optimized by means of uncoupled CFD and FEM simulations in order to assess the strength of the component. This paper deals with a structural stress analysis of the cylinder head considering the thermal loads computed through an uncoupled CFD simulations of cylinder combustion and in cooling flow passages. The FE model includes the contact interaction between the main parts of the cylinder head assembly and it also considers the effects of bolts tightening and valve springs. Temperature dependent non-linear material properties are considered. The results, in term of temperature field, are validated by comparing with those obtained by means of experimental analyses; the engine has been instrumented with thermocouples on crank case and on cylinder head.

The onset of cavitating conditions inside the nozzle of diesel injectors is known to play a major role on spray characteristics, especially on jet penetration and break-up. In this work, for the first time a Direct Numerical Simulation (DNS) based on the Lattice Boltzmann Method (LBM) is applied to study the fluid dynamic field inside the nozzle of a cavitating diesel injector. The formation of the cavitating region is determined via a multi-phase approach based on the Shan-Chen Equation of State and its most recent enhancements. The evolution of cavitation bubbles is followed and the characteristic numbers, i.e., Cavitation Number (CN) and discharge coefficient (Cd) are evaluated. The results obtained by the LBM simulation are compared to both numerical and experimental data present in literature.

An engine head of a common rail direct injection engine with three in line cylinders for Light Transportation Vehicle (LTV) applications has been analyzed and optimized by means of uncoupled CFD and FEM simulations in order to assess the strength of the components. This paper deals with a structural stress analysis of the cylinder head considering the thermal loads computed through an CFD simulation and a detailed FV heat-transfer analysis. The FE model of the cylinder head includes the contact interaction between the main parts of the cylinder head assembly and it is subjected to the gas pressure, thermal loads and the effects of bolts tightening and valve springs. The results, in term of temperature field, are validated by comparing with those obtained by means of experimental analyses. Then a fatigue assessment of the cylinder head has been performed using a multi-axial fatigue criterion.

Fuel droplet collision plays an important role in the mixture formation mechanism in Internal Combustion Engines (ICE), since this process significantly modifies the droplet sizes and subsequent spray development and combustion. But one of the major problems in the simulation of the droplet collision process is that the criteria employed to determine outcomes of collisions have not been assessed for accuracy under diesel spray conditions. The numerical simulation of multiphase flows is a challenging subject due to the difficulty in the tracking of interfaces, the mass conservation of each fluid and the treatment of large density ratio and surface tension. In this paper a fully 3D two-phase Lattice-Boltzmann Method (LBM) is used to perform Direct Numerical Simulation (DNS) of droplet collision at diesel-like conditions.

Turbulence modeling for fuel spray simulation plays a prominent role in the understanding of the flow behavior in Internal Combustion Engines (ICEs). Currently, a lot of research work is actively spent on Large Eddy Simulation (LES) turbulence modeling as a replacement option of standard Reynolds averaged approaches in the Eulerian-Lagrangian spray modeling framework, due to its capability to accurately describe flow-induced spray variability and to the lower dependence of the results on the specific turbulence model and/or modeling coefficients. The introduction of LES poses, however, additional questions related to the implementation/adaptation of spray-related turbulence sources and to the rise of conflicting numerics and grid requirements between the Lagrangian and Eulerian parts of the simulated flow.

Scale-resolving turbulence modeling for engine flow simulation has constantly increased its popularity in the last decade. In contrast to classical RANS modeling, LES-like approaches are able to resolve a larger number of unsteady flow features. In principle, this capability allows to accurately predict some of the key parameters involved in the development and optimization of modern engines such as cycle-to-cycle variations in a DI engine. However, since multiple simulated engine cycles are required to extract reliable flow statistics, the spatial and temporal resolution requirements of pure LES still represent a severe limit for its wider application on realistic engine geometries. In this context, Hybrid URANS-LES methodologies can therefore become a potentially attractive option. In fact, their task is to preserve the turbulence scale-resolving in the flow core regions but at a significantly lower computational cost compared to standard LES.

The LES hybridization of standard two-equation turbulence closures is often achieved leaving formally unchanged the turbulent viscosity expression in the URANS and LES modes of operation. Although generally convenient in terms of ease of implementation, this choice leaves some theoretical consistency questions unanswered, the most obvious being the actual meaning of the two transported turbulent scalars and their exact role in the modeled viscosity build-up. A possible remedy to this is represented by the simultaneous modification of one or both the turbulent transport equations and of the turbulent viscosity formula, for which a standard LES behavior is enforced whenever needed. The present work compares a conventional DES-based hybrid model with a consistency-enforcing modified variant for turbulent fuel spray simulation. In our case, LES-mode consistency is accomplished by excluding the second turbulent scalar quantity from the viscosity calculation.

Batteries are the key elements for the massive electrification of the transport sector. With the rapidly growing popularity of electric vehicles, it is becoming increasingly important to characterize the behavior of battery packs through fast and accurate numerical models, in order to support experimental activities. A coupled electro-thermal simulation framework is required, as it is the only way to realistically represent the interactions between real world battery pack performances and the vehicle-level thermal management strategies. The purpose of this work is to pave the way for a comprehensive methodology for the development of a supporting modeling framework, to efficiently complement experiments in the optimal design and integration of battery packs.

Due to their ability to store higher electrical energy, lithium ion batteries are the most promising candidates for electric and hybrid electric vehicles, whose market share is growing fast. Heat generation during charge and discharge processes, frequently undergone by these batteries, causes temperature increase and thermal management is indispensable to keep temperature in an appropriate level. In this paper, a coupled Lattice Boltzmann-Finite Volume model for the three-dimensional transient thermal analysis of an air-cooled Li-ion battery module is presented. As it has already been successfully used to deal with several fluid-dynamics problems, the Lattice Boltzmann method is selected for its simpler boundary condition implementation and complete parallel computing, which make this approach promising for such applications.

The port-logistic industry has a significant impact on the urban environment nearby ports and on the surrounding coastal areas. This is due to the use of large auxiliary power systems on ships operating during port stays, as well as to the employment of a number of fossil fuel powered road vehicles required for port operations. The environmental impact related to the use of these vehicles is twofold: on one hand, they contribute directly to port emissions by fuel consumption; on the other hand, they require some of the ship auxiliary systems to operate intensively, such as the ventilation system, which must operate to remove the pollutants produced by the vehicle engines inside the ship. The pathway to achieve decarbonization and mitigation of energy use in ports involves therefore the adoption of alternative and cleaner technology solutions for the propulsion systems of such port vehicles.