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A KIA Soul was instrumented to measure the relative velocity (magnitude and yaw angle) at the front of the vehicle and in-cabin sound at a location close to the side glass near the A-pillar vortex impingement. Tests were conducted at a proving ground under a range of conditions from low wind conditions (~3 m/s) to moderate (7-8 m/s) wind speeds. For any given set of atmospheric conditions the velocity and sound data at any given position on the proving ground were noted to be very repeatable, indicating that the local wakes dominated the "turbulent" velocity field. Testing was also conducted in an aeroacoustic wind tunnel in smooth flow and with a number of novel turbulence generating methods. The resulting sounds were analyzed to study the modulation at frequencies likely to result in fluctuation strength type noise.

Wind tunnels provide a convenient, repeatable method of assessing vehicle engine cooling, yet important draw-backs are the lack of a moving ground and rotating wheels, blockage constraints and, in some tunnels, the inability to simulate ambient temperatures. A series of on-road and wind-tunnel experiments has been conducted to validate a process for evaluating vehicle cooling system performance in a high blockage aerodynamic wind tunnel with a fixed ground simulation. Airflow through the vehicle front air intake was measured via a series of pressure taps and the wind-tunnel velocity was adjusted to match the corresponding pressures found during the road tests. In order to cope with the inability to simulate ambient temperatures, the technique of Specific Dissipation (SD) was used (which has previously been shown to overcome this problem).

The vehicle WLTP and RDE homologation test cycles are pushing the engine technology toward the implementation of different solutions aimed to the exhaust gases emission reduction. The tightening of the policy on the Auxiliary Emission Strategy (A.E.S.), including those for the engine component protection, faces the Spark Ignited (S.I.) engines with the need to replace the fuel enrichment as a means to cool down both unburnt mixture and exhaust gases to accomplish with the inlet temperature turbine (TiT) limit. Among the whole technology solutions conceived to make SI engine operating at lambda 1.0 on the whole operation map, the water injection is one of the valuable candidates. Despite the fact that the water injection has been exploited in the past, the renewed interest in it requires a deep investigation in order to outcome its potential as well as its limits.

Recent and forthcoming fuel consumption reduction requirements and exhaust emissions regulations are forcing the development of innovative and particularly complex intake-engine-exhaust layouts. In the case of Spark Ignition (SI) engines, the necessity to further reduce fuel consumption has led to the adoption of direct injection systems, displacement downsizing, and challenging intake-exhaust configurations, such as multi-stage turbocharging or turbo-assist solutions. Further, the most recent turbo-GDI engines may be equipped with other fuel-reduction oriented technologies, such as Variable Valve Timing (VVT) systems, devices for actively control tumble/swirl in-cylinder flow components, and Exhaust Gas Recirculation (EGR) systems. Such degree of flexibility has a main drawback: the exponentially increasing effort required for optimal engine control calibration.

This paper presents a 14 degrees of freedom vehicle model. Despite numerous software are nowadays commercially available, the model presented in this paper has been built starting from a blank sheet because the goal of the authors was to realize a model suitable for real-time simulation, compatible with the computational power of typical electronic control units, for on-board applications. In order to achieve this objective a complete vehicle dynamics simulation model has been developed in Matlab/Simulink environment: having a complete knowledge of the model's structure, it is possible to adapt its complexity to the computational power of the hardware used to run the simulation, a crucial feature to achieve real-time execution in actual ECUs.

New and upcoming exhaust emissions regulations and fuel consumption reduction requirements are forcing the development of innovative and particularly complex intake-engine-exhaust layouts. Especially in the case of Compression Ignition (CI) engines, the HC-CO-NOx-PM after-treatment system is becoming extremely expensive and sophisticated, and the necessity to further reduce engine-out emission levels, without significantly penalizing fuel consumption figures, may lead to the adoption of intricate and challenging intake-exhaust systems configurations. The adoption of both long- and short-route Exhaust Gas Recirculation (EGR) systems is one example of such situation, and the need to precisely measure (or estimate) mass flow rates in the various elements of the gas exchange circuit is one of the consequences.

While the Diesel Particulate Filter (DPF) is actually a quasi-standard equipment in the European Diesel passenger cars market, an interesting solution to fulfill NOx emission limits for the next EU 6 legislation is the application of a Selective Catalytic Reduction (SCR) system on the exhaust line, to drastically reduce NOx emissions. In this context, one of the main issues is the performance of the SCR system during cold start and warm up phases of the engine. The exhaust temperature is too low to allow thermal activation of the reactor and, consequently, to promote high conversion efficiency and significant NOx concentration reduction. This is increasingly evident the smaller the engine displacement, because of its lower exhaust system temperature (reduced gross power while producing the same net power, i.e., higher efficiency).

This paper summarises the effects of turbulence on the aerodynamics of road vehicles, including effects on forces and aero-acoustics. Data are presented showing that a different design of some vehicles may result when turbulent flow is employed. Methods for generating turbulence, focusing on physical testing in full-size wind tunnels, are discussed. The paper is Part Two of a review of turbulence and road vehicles. Part One (Cooper and Watkins, 2007) summarised the sources and nature of the turbulence experienced by surface vehicles.

This paper is the first of two papers that address the simulation and effects of turbulence on surface vehicle aerodynamics. This, the first paper, focuses on the characteristics of the turbulent flow field encountered by a road vehicle. The natural wind environment is usually unsteady but is almost universally replaced by a smooth flow in both wind tunnel and computational domains. In this paper, the characteristics of turbulence in the relative-velocity co-ordinate system of a moving ground vehicle are reviewed, drawing on work from Wind Engineering experience. Data are provided on typical turbulence levels, probability density functions and velocity spectra to which vehicles are exposed. The focus is on atmospheric turbulence, however the transient flow field from the wakes of other road vehicles and roadside objects are also considered.

In PFI and GDI engines the tumble motion is the most important charge motion for enhancing the in-cylinder turbulence level at ignition time close to the spark plug position. In the open literature different studies were reported on the tumble motion, experimental and not. In the present paper the research activity on the tumble generation at partial load and very partial load conditions was presented. The added value of the analysis was the study of the effect of the throttle valve rotational direction on the tumble motion and the final level of turbulence at the ignition time close to the spark plug location. The focus was to determine if the throttle rotational direction was crucial for the tumble ratio and the turbulence level. The analyzed engine was a PFI 4-valves motorcycle engine. The engine geometry was formed by the intake duct and the cylinder. The CFD code was FIRE AVL code 2013.1.

New gasoline engine design is highly influenced by CO2 and emission limits defined by legislations, the demand for real conditions fuel economy, higher torque, higher specific power and lower cost. To reach the requirements coming from the end-users and legislations, especially for SI engines, several technologies are available, such as downsizing, including turbocharging in combination with direct injection. These technologies allow to solve the main issues of gasoline engines in terms of efficiency and performance which are knocking, part-load losses, and thermal stress at high power conditions. Moreover, other possibilities are under evaluation to allow further steps of enhancement for the even more challenging requirements. However, the benefits and costs given by the mix of these technologies must be accurately evaluated by means of objective tools and procedures in order to choose among the best alternatives.

Alternative and oxygenated fuels are nowadays being studied in order to increase engine efficiency and reduce exhaust emissions and also to limit the automotive industry's economical dependency from crude oil. These fuels are considered more ecological compared to hydrocarbons because they are obtained using renewable sources. Fuels like anhydrous/hydrous ethanol, methanol or alcohol/gasoline blends which are injected in liquid form must vaporize quickly, especially in direct injection engines, therefore their volatility is a very important factor and strongly depends on thermodynamic conditions and chemical properties. When a multi-component fuel blend is injected into a low pressure environment below its saturation pressure, a rapid boiling of the most volatile component triggers a thermodynamic atomization mechanism. These kinds of sprays show smaller droplets and lower penetration compared to mechanical break up.

Knock is a non-deterministic phenomenon and its intensity is typically defined by a non-symmetrical distribution, under fixed operating conditions. A statistical approach is therefore the correct way to study knock features. Typically, intrinsically deterministic knock models need to artificially introduce Cycle-to-Cycle Variation (CCV) of relevant combustion parameters, or of cycle initial conditions, to generate different knock intensity values for a given operating condition. Their output is limited to the percentage of knocking cycles, once the user imposes an arbitrary knock intensity threshold to define the correlation between the number of knocking events and the Spark Advance (SA). In the first part of the paper, a statistical analysis of knock intensity is carried out: for different values of SA, the probability distributions of an experimental Knock Index (KI) are self-compared, and the characteristics of some percentiles are highlighted.

Vortices formed around the A-pillar region dictates the pressure distribution on the side panels of a passenger vehicle and also can lead to aerodynamic noise generation. This paper compares the suitability of various turbulence models in simulating the flow behind a vehicle A-pillar region under laboratory operating conditions. Commercial software's (FLUENT and SWIFT) were used to compare the performance of various turbulence models. In FLUENT, a simplified vehicle model with slanted A-pillar geometry was generated using GAMBIT and in SWIFT, the simplified vehicle model was generated using Fame Hybrid. Computational Fluid Dynamics (CFD) simulations were carried out using FLUENT under steady state conditions using various turbulence models (k-, k- Realize, k- RNG, k- and Spalart Allamaras). In SWIFT, k-, A-RSM and HTM2 turbulence models were used for the steady state simulations. Investigations were carried out at velocities of 60, 100 and 140km/h and at 0-degree yaw angle.

External gear pumps are widely used in many different applications because of their relatively low costs and high performances, especially in terms of volumetric and mechanical efficiency. The main weaknesses of external gear pumps can be summarized as follows: 1 Sudden increase or decrease of pressure inside volumes between teeth, which could lead respectively to noise emissions and to cavitation onset; 2 Necessity of limiting power losses and increasing volumetric efficiency, obtainable by reducing leakage flows between components; 3 Need of maintaining an ad-hoc minimum lubrication film thickness. In recent years many efforts, in terms of mathematical models and experimental tests, were done in order to limit energy losses and noise emissions. With the aim of deeply studying dynamic behaviour of external gear pumps and addressing their design, a 1D model was developed by means AMESim® code.

This paper summarizes the main studies carried out by the authors for the development of indexes for remote combustion sensing applicable to different combustion types, i.e. conventional gasoline and diesel combustions, diesel PCCI and dual fuel gasoline-diesel RCCI. It is well-known that the continuous development of modern Internal Combustion Engine (ICE) management systems is mainly aimed at complying with upcoming increasingly stringent regulations throughout the world, both for pollutants and CO2 emissions. Performing an efficient combustion control is crucial for efficiency increase and pollutant emissions reduction. Over the past years, the authors of this paper have developed several techniques to estimate the most important combustion indexes for combustion control, without using additional cylinder pressure sensors but only using the engine speed sensor (always available on board) and accelerometers (usually available on-board for gasoline engines).

The increasing request for pollutant emissions reduction spawned a great deal of research in the field of innovative combustion methodologies, that allow obtaining a significant reduction both in particulate matter and NOx emissions. Unfortunately, due to their nature, these innovative combustion strategies are very sensitive to in-cylinder thermal conditions. Therefore, in order to obtain a stable combustion, a closed-loop combustion control methodology is needed. Prior research has demonstrated that a closed-loop combustion control strategy can be based on the real-time analysis of in-cylinder pressure trace, that provides important information about the combustion process, such as Start (SOC) and Center of combustion (CA50), pressure peak location and torque delivered by each cylinder. Nevertheless, cylinder pressure sensors on-board installation is still uncommon, due to problems related to unsatisfactory measurement long term reliability and cost.

Exhaust heat recovery systems are used to make use of otherwise wasted heat from a car engine. The purpose of exhaust heat recovery systems is to reduce the fuel consumption of the car and consequently reduce CO2 emissions. The unique system design described herein utilises thermoelectric generators (TEGs) and heat pipes with its key advantage being it is a passive solid state design. The use of these components creates a few design constraints. For example, both the TEGs and heat pipes have operating temperature limitations. In this paper, a naphthalene heat pipe preheat exchanger is proposed to deal with this problem. Exhaust conditions measured from a representative spark ignition engine were used in a numerical simulation to predict the performance of the exhaust heat recovery system. If 8 modules are used and the engine is producing 8kW of mechanical power, the system is predicted to produce 53.75W of electrical power.

The overall performance of direct injection (DI) engines is strictly correlated to the fuel liquid spray evolution into the cylinder volume. More in detail, spray behavior can drastically affect mixture formation, combustion efficiency, cycle to cycle engine variability, soot amount, and lubricant contamination. For this reason, in DI engine an accurate numerical reproduction of the spray behavior is mandatory. In order to improve the spray simulation accuracy, authors defined a new atomization model based on experimental evidences about ligament and droplet formations from a turbulent liquid jet surface. The proposed atomization approach was based on the assumption that the droplet stripping in a turbulent liquid jet is mainly linked to ligament formations. Reynolds-averaged Navier Stokes (RANS) simulation method was adopted for the continuum phase while the liquid discrete phase is managed by Lagrangian approach.

In the past years, stringent emission regulations for Internal Combustion (IC) engines produced a large amount of research aimed at the development of innovative combustion methodologies suitable to simultaneously reduce fuel consumption and engine-out emissions. Previous research demonstrates that the goal can be obtained through the so-called Low Temperature Combustions (LTC), which combine the benefits of compression-ignited engines, such as high compression ratio and unthrottled lean operation, with a properly premixed air-fuel mixture, usually obtained injecting gasoline-like fuels with high volatility and longer ignition delay. Gasoline Partially Premixed Combustion (PPC) is a promising LTC technique, mainly characterized by the high-pressure direct-injection of gasoline and the spontaneous ignition of the premixed air-fuel mixture through compression, which showed a good potential for the simultaneous reduction of fuel consumption and emissions in CI engines.