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In-cylinder spray imaging by Mie scattering has been taken with frame rates up to 27,000 fps, along with high speed video photography of chemiluminescence and soot thermal radiation. Spectroscopic measurements have confirmed the presence of OH*, CH* and C2* emissions lines, and their magnitude relative compared to soot radiation. Filtering for CH* has been used with both the high speed video and a Photo-Multiplier Tube (PMT). The PMT signals have been found to correlate with the rate of heat release derived from in-cylinder pressure measurements. A high power photographic strobe has been used to illuminate the fuel spray. Images show that the fuel spray can strike the ground strap of the spark plug, break up, and a fuel cloud then drifts over and under the strap through the spark plug gap. Tests have conducted at two different spark plug orientations using a single spark strategy.

Particulate emissions from gasoline direct injection (GDI) engines continue to be a topic of substantial research interest. Forthcoming regulation both in the USA and the EU will further reduce their emission and drive innovation. Substantial research effort is spent undertaking experiments to understand, characterize, and research particle number (PN) emissions from engines and vehicles. Recent advances in computing power, data storage, and understanding of artificial intelligence algorithms now mean that these are becoming an important tool in engine research. In this work a random forest (RF) algorithm is used for the prediction of PN emissions from a highly boosted (up to 32 bar BMEP) GDI engine. Particle size, concentration, and the accumulation mode geometric standard deviation (GSD) are all predicted by the model. The results are analysed and an in depth study on parameter importance is carried out.

The introduction of transient test cycles and the focus on real world driving emissions has increased the importance of ensuring the NOx and soot emissions are controlled during transient manoeuvres. At the same time, there is a drive to reduce the number of calibration variables used by engine control strategies to reduce development effort and costs. In this paper, a control orientated combustion model, [1], and model predictive control strategy, [2], that were developed in simulation and reported in earlier papers, are applied to a Diesel engine and demonstrated in a test vehicle. The paper describes how the control approach developed in simulation was implemented in embedded hardware, using an FPGA to accelerate the emissions calculations. The development of the predictive controller includes the application of a simplified optimisation algorithm to enable a real-time calculation in the test vehicle.

In-cylinder temperature measurements are vital for the validation of gasoline engine modelling and useful in their own right for explaining differences in engine performance. The underlying chemical reactions in combustion are highly sensitive to temperature and affect emissions of both NOx and particulate matter. The two techniques described here are complementary, and can be used for insights into the quality of mixture preparation by measurement of the in-cylinder temperature distribution during the compression stroke. The influence of fuel composition on in-cylinder mixture temperatures can also be resolved. Laser Induced Grating Spectroscopy (LIGS) provides point temperature measurements with a pressure dependent precision in the range 0.1 to 1.0 % when the gas composition is well characterized and homogeneous; as the pressure increases the precision improves.

Models for the convective heat transfer from the combustion gases to the walls inside a spark ignition engine are an important keystone in the simulation tools which are being developed to aid engine optimization. The existing models have, however, been cited to be inaccurate for hydrogen, one of the alternative fuels currently investigated. One possible explanation for this inaccuracy is that the models do not adequately capture the effect of the gas properties. These have never been varied in a wide range because air and ‘classical’ fossil fuels have similar values, but they are significantly different in the case of hydrogen. As a first step towards a fuel independent heat transfer model, we have investigated the effect of the gas properties on the heat flux in a spark ignition engine.

Knowledge of fuel mass injected in an individual cycle is important for engine performance and modeling. At the moment, such measurements are not possible on engine or in real time. In this article, a new method using Coriolis flow meters (CFMs) and a new, patented, signal processing technique, known as the Prism, are introduced. CFMs are extensively used for flow measurement both in the automotive industry and further afield and, when coupled with the Prism, have the potential to make these challenging high-speed measurements. A rig-based feasibility study was conducted injecting very small quantities of diesel (3 mg) at pressures of up to 1000 bar at simulated engine speeds of up to 4000 rpm. The results show that these small quantities can in principle be measured. The results also reveal a previously unknown behavior of CFMs when measuring very low flow rates at high speed.

Spray guided Direct Injection Gasoline Engines are a key enabler to reducing CO2 emissions and improving the fuel economy of light duty vehicles. Particulate emissions from these engines have been shown to be lower than from first generation direct injection gasoline engines, but they may still be significantly higher than port fuel injected engines due to the reduced time available for mixture preparation and increased incidence of fuel impingement on the piston crown and combustion chamber surfaces. These factors are particularly severe in the period following a cold start. Both nuclei and accumulation mode particle size and number concentration were measured using a Cambustion differential mobility spectrometer. These data are reported for different coolant temperature intervals during the warm-up period. The bulk composition was determined using thermo-gravimetric analysis, and PM mass fractions are given for different volatility ranges and for elemental carbon.

Particulate Emissions from Homogeneous Charge Compression Ignition (HCCI) combustion are routinely assumed to be negligible. It is shown here that this is not the case when HCCI combustion is implemented in a direct injection gasoline engine. The conditions needed to sustain HCCI operation were realized using the negative valve overlap method for trapping high levels of residual exhaust gases in the cylinder. Measurements of emitted particle number concentration and electrical mobility diameter were made with a Cambustion DMS500 over the HCCI operating range possible with this hardware. Emissions of oxides of nitrogen, carbon monoxide and unburned hydrocarbons were also measured. These data are presented and compared with similar measurements made under conventional spark ignition (SI) operation in the same engine. Under both SI and HCCI operation, a significant accumulation mode was detected with particle equivalent diameters between 80 and 100 nm.

The blending of oxygenated compounds with gasoline is projected to increase because oxygenate fuels can be produced renewably, and because their high octane rating allows them to be used in substitution of the aromatic fraction in gasoline. Blending oxygenates with gasoline changes the fuels' properties and can have a profound affect on the distillation curve, both of which are known to affect engine-out emissions. In this work, the effect of blending methanol and ethanol with gasoline on unburned hydrocarbon and particulate emissions is experimentally determined in a spray guided direct injection engine. Particulate number concentration and size distribution were measured using a Cambustion DMS500. These data are presented for different air fuel ratios, loads, ignition timings and injection timings. In addition, the ASTM D86 distillation curve was modeled using the binary activity coefficients method for the fuel blends used in the experiments.

Planar Laser-Induced Fluorescence has been widely accepted and applied to measurements of fuel concentration distributions in IC engines. The need for such measurements has increased with the introduction of Direct Injection (DI) gasoline engines, where it is critical to understand the influence of mixture inhomogeneity on ignition and subsequent combustion, and in particular the implications for cyclic variability. The apparent simplicity of PLIF has led to misunderstanding of the technique when applied to quantitative measurements of fuel distributions. This paper presents a series of engineering methods for optimizing, calibrating and referencing, which together demonstrate a quantitative measure of fuel concentration with an absolute accuracy of 10%. PLIF is widely used with single component fuels as carriers for the fluorescent tracers.

Increasing biodiesel content in mineral diesel is being promoted considerably for road transportation in Europe. With positive benefits in terms of net CO2 emissions, biofuels with compatible properties to those of conventional diesel are increasingly being used in combustion engines. In comparison to standard diesel fuel, the near zero sulphur content and low levels of aromatic compounds in biodiesel fuel can have a profound effect not only on combustion characteristics but on engine-out emissions as well. This paper presents analysis of particulate matter (PM) emissions from a turbo-charged, common rail direct injection (DI) V6 Jaguar engine operating with an RME (rapeseed methyl ester) biodiesel blended with ultra low sulphur diesel (ULSD) fuel (B30 - 30% of RME by volume). Three different engine load and speed conditions were selected for the test and no modifications were made to the engine hardware or engine management system (EMS) calibration.

Particulate Matter (PM) legislation for gasoline engines and the introduction of gasoline/ethanol blends, make it important to know the effect of fuel composition on PM emissions. Tests have been conducted with fuels of known composition in both a single-cylinder engine and V8 engine with a three-way catalyst. The V8 engine used an unleaded gasoline (PURA) with known composition and distillation characteristics as a base fuel and with 10% by volume ethanol. The single-cylinder engine used a 65% iso-octane - 35% toluene mixture as its base fuel. The engines had essentially the same combustion system, with a centrally mounted 6-hole spray-guided direct injection system. Particle size distributions were recorded and these have also been converted to mass distributions. Filter samples were taken for thermo-gravimetric analysis (TGA) to give composition information. Both engines were operated at 1500 rpm under part load.

Model M15 gasoline fuels have been created from pure fuel components, to give independent control of volatility, the heavy end content and the aromatic content, in order to understand the effect of the fuel properties on Gasoline Direct Injection (GDI) fuel spray behaviour and the subsequent particulate number emissions. Each fuel was imaged at a range of fuel temperatures in a spray rig and in a motored optical engine, to cover the full range from non-flashing sprays through to flare flashing sprays. The spray axial penetration (and potential piston and liner impingement), and spray evaporation rate were extracted from the images. Firing engine tests with the fuels with the same fuel temperatures were performed and exhaust particulate number spectra captured using a DMS500 Mark II Particle Spectrometer.

The increased efficiency and specific output with Gasoline Direct Injection (GDI) engines are well known, but so too are the higher levels of Particulate Matter emissions compared with Port Fuel Injection (PFI) engines. To minimise Particulate Matter emissions, then it is necessary to understand and control the mixture preparation process, and important insights into GDI engine mixture preparation and combustion can be obtained from optical access engines. Such data is also crucial for validating models that predict flows, sprays and air fuel ratio distributions. The purpose of this paper is to review a number of optical techniques; the interpretation of the results is engine specific so will not be covered here. Mie scattering can be used for semi-quantitative measurements of the fuel spray and this can be followed with Planar Laser Induced Fluorescence (PLIF) for determining the air fuel ratio and temperature distributions.

To optimize internal combustion engines (ICEs), a good understanding of engine operation is essential. The heat transfer from the working gases to the combustion chamber walls plays an important role, not only for the performance, but also for the emissions of the engine. Besides, thermal management of ICEs is becoming more and more important as an additional tool for optimizing efficiency and emission aftertreatment. In contrast little is known about the convective heat transfer inside the combustion chamber due to the complexity of the working processes. Heat transfer measurements inside the combustion chamber pose a challenge in instrumentation due to the harsh environment. Additionally, the heat loss in a spark ignition (SI) engine shows a high temporal and spatial variation. This poses certain requirements on the heat flux sensor. In this paper we examine the heat transfer in a production SI ICE through the use of Thin Film Gauge (TFG) heat flux sensors.

The emission of nanoparticles from combustion engines has been shown to have a poorly understood impact on the atmospheric environment and human health, and legislation tends to err on the side of caution. Researchers have shown that Gasoline Direct Injection (GDI) engines tend to emit large amounts of small-sized particles compared to diesel engines fitted with Diesel Particulate Filters (DPFs). As a result, the particulate number emission level of GDI engines means that they could face some challenges in meeting the likely EU6 emissions requirement. This paper presents size-resolved particle number emissions measurements from a spray-guided GDI engine and evaluates the performance of an Evaporation Tube (ET). The performance of an Evaporation Tube and hot air dilution system with a 7:1 dilution ratio has been studied, as the EU legislation uses these to exclude volatile particles.

In light of forthcoming particle number legislation for light-duty passenger vehicles, time-resolved Particle Mass (PM) and Particle Number (PN) emissions over the New European Drive Cycle (NEDC) are reported for four current vehicle technologies; modern diesel, with and without a Diesel Particulate Filter (DPF), Direct Injection Spark Ignition (DISI) gasoline and multi-point Port Fuel Injection (PFI) gasoline. The PN and PM emissions were ordered (highest to lowest) according to: Non-DPF diesel ≻ DISI ≻ PFI ~ DPF diesel. Both the non-DPF diesel and DISI vehicles emitted PN and PM continuously over the NEDC. This is in contrast with both the DPF diesel and PFI vehicles which emitted nearly all their PN and PM during the first 200 seconds. The PFI result is thought to be a consequence of cold-start mixture preparation whilst several possible explanations are offered for the DPF diesel trend.

A Cambustion Differential Mobility Spectrometer (DMS500), Dekati Electrical Low Pressure Impactor (ELPI), TSI Condensation Particle Counter (CPC) and AVL Photo-Acoustic Soot Sensor (PASS) were compared for measurements of emitted Particulate Matter (PM) from a Direct Injection Spark Ignition (DISI) vehicle on the New European Drive Cycle (NEDC) and at steady speed operating points. The exhaust was diluted in a Constant Volume Sampler (CVS) before being measured. Transient size spectral data from the DMS500 and ELPI is presented. PM Number rate and total PM number emissions are presented for the DMS500, ELPI and CPC. The DMS500 and ELPI data are post-processed for PM mass, and presented with data from the PASS. The instrument responses were correlated against each other. Qualitative agreement was generally found between all instruments. The agreement was closer for PM mass measurements than for measurements of PM number.

A Spray Guided Direct Injection (SGDI) engine has been shown to emit less Particulate Matter (PM) than a first generation (wall guided) Direct Injection Spark Ignition (DISI) engine. The reduction is attributed to the reduced incidence of fuel-wall impingement and higher fuel injection pressure. The extent to which this is true was investigated by comparison between single cylinder SGDI and DISI engines. Both engines were also operated with conventional port injection to provide a baseline. Feedgas PM number concentration and size spectra were measured using a Cambustion differential mobility spectrometer for the fuels iso-octane and toluene with a range of Air-Fuel Ratios (AFRs), ignition and injection timings.

Color-ratio pyrometry (CRP) is a technique for estimating the temperature and loading of soot, based on its thermal emission spectrum. This technique is contrasted with conventional two-color pyrometry which requires absolute measurements of the radiation intensity, either at two specific wavelengths or ranges of wavelengths. CRP uses two ratios, obtained by measuring the radiation intensity for three wavelengths or wavelength bands. CRP has been implemented here by using a digital CCD camera, and full details of the calibration are reported. Because of uncertainties in the emissivity of reference sources (such as tungsten ribbon lamps, in which the emissivity depends on temperature and wavelength), then a spectroscopic calibration of the CCD camera has been used. Use of a CCD camera is not straightforward because of internal digital signal processing (DSP), so full details are given of the calibration and technique implementation.