E. Winklhofer

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• Dr.
• Head of Department at AVL LIST GMBH

div class="section abstract"> Hydrogen promises to provide some highly desired features for clean and efficient combustion, but harvesting efficiency and emission potentials as well as meeting engine durability requirements needs careful adaption of both, combustion system components and engine operation strategies. Key points for H₂-ICE...

A thermodynamic method for the evaluation of charge “parcel” temperatures at the moment of self-ignition in SI engines has been applied to a series of combustion cycles which were ignited by pre-ignition events. The temperature evaluation method is based on measurement of the degree crank angle at which the rate of heat release surpasses the backgr...

A heavy-duty diesel engine has been constructed to provide full optical access to the piston bowl with a window forming the bottom of the “optical” piston. The engine is operated up to 1400 rpm, with peak firing pressure of up to 160 bar and IMEP levels of up to 20 bar. Fuel injection is accomplished with a common rail system and an externally driv...

Welche Eigenschaften einer Verbrennung erfordern optische Messverfahren, welcher Nutzen wird daraus für den Motorentwicklungsvorgang gewonnen? Mit der Vorgabe dieser Fragestellung ist in den nachfolgenden Tabellen eine Übersicht über verschiedene optische Messtechniken und deren Anwendungsmöglichkeiten angeführt. Von den vielfältigen Methoden, die...

Piston to liner friction is responsible for a significant part (up to 50%) of total engine friction losses. Engine manufacturers use liner offset designs to address this issue and potentially reduce friction losses as is to be expected from theoretical considerations. A “floating liner” single cylinder engine was used to directly measure the effect...

The paper describes a method to identify and analyze pre-ignition (PI) events appearing in engine and vehicle RDE drive cycle tests or similar transient and stationary test schedules. A specific requirement in such long duration drive cycles is the large amount of data to be recorded for each combustion cycle and the data processing during and afte...

In the workflow of SI engine development, focus is given to the selection, integration and calibration of three way catalyst units (TWC). The need for efficient and clean combustion in RDE test situations imposes restrictions to fuel enrichment as otherwise used for component protection. Furthermore, as highly dynamic driving modes require precise...

The paper discusses the application of routine engine strip down tests for the assessment of an engine's friction behavior and the contribution of individual engine components. Cylinder pressure effects are frequently tested with the boost / motored test procedure. Some results are presented together with a discussion of the tests applicability. Th...

Welche Eigenschaften einer Verbrennung erfordern optische Messverfahren, welcher Nutzen wird daraus für den Motorentwicklungsvorgang gewonnen? Mit der Vorgabe dieser Fragestellung ist in den nachfolgenden Tabellen eine Übersicht über verschiedene optische Messtechniken und deren Anwendungsmöglichkeiten angeführt. Von den vielfältigen Methoden, die...

As fuel injection pressures keep rising, questions focus on additional benefits to be gained from the considerable efforts to achieve and handle the fuel pressure increments. The aim of fuel injection processes is to support the mixing of fuel molecules with oxygen. The steps towards this goal include fuel atomization, evaporation, heat transfer fr...

As fuel injection pressures keep rising, questions focus on additional benefits to be gained from the considerable efforts to achieve and handle the fuel pressure increments. The aim of fuel injection processes is to support the mixing of fuel molecules with oxygen. The steps towards this goal include fuel atomization, evaporation, heat transfer fr...

Verbrennungsdiagnostik wird in der Motorenentwicklung immer dann eingesetzt, wenn bei Messungen von Verbrauch, Leistung und Emissionen ungenutztes Potenzial im Vergleich zu thermodynamisch möglichen Zielwerten festgestellt wird. Bei den hohen Zielanforderungen, die an moderne Motoren gestellt werden, ist zumindest eine thermodynamische Verbrennungs...

Flame analysis techniques are shown to identify combustion issues relevant in the development of modern spark ignition (SI) engines. Access to the combustion chamber is gained with fiber optic spark plug sensors, crank angle resolved, broadband flame radiation signals are recorded for as many combustion cycles as requested by a specific engine or v...

Gasoline direct injection (GDI) and turbocharging (TC) are central techniques for modern SI engines to enable the control of combustion features over a wide range of operating modes. Engine modules to handle the gas exchange together with fuel injection equipment to support mixture formation for clean combustion are key elements to meet fuel effici...

Piston to liner friction is responsible for up to 50% of total engine friction losses. A "floating liner" single cylinder engine together with measurement and test bed modules has been developed to enable high precision piston to liner friction measurement at engine operation conditions relevant for today's and future engine test cycles. The engine...

Verbrennungsdiagnostik wird in der Motorenentwicklung immer dann eingesetzt, wenn bei Messungen von Verbrauch, Leistung und Emissionen ungenutztes Potenzial im Vergleich zu thermodynamisch möglichen Zielwerten festgestellt wird. Bei den hohen Zielanforderungen, die an moderne Motoren gestellt werden, ist zumindest eine thermodynamische Verbrennungs...

Tests have been performed of fuel pressure's influence on injector fuel flow, on spray and mixture formation and on combustion. Optical diagnostics were applied to measure fuel flow in 2D model spray hole geometries, to study spray stability and analyze flow in the bowl of combustion chambers. Main finding was that spray-togas momentum transfer int...

A method for evaluating the state of a fuel-air mixture and/or the combustion in a combustion chamber of an internal combustion engine, with sample signals of flame light signals being stored in a database, and with flame light signals of the combustion in the combustion chamber being detected and compared with the stored sample signals, and with a...

Der Verbrennungsmotor bezieht seine Energie aus der Umsetzung der chemischen Energie in Wärme. Diesen Vorgang zu verstehen, so effizient und schadstoffarm wie möglich zu gestalten ist das Ziel der Verbrennungsdiagnostik. Das Kapitel beschreibt die Indiziermessung nebst ihren Bestandteilen Sensoren, Signalaufbereitung, Datenerfassung und Steuerung d...

Das Auftreten von Flammenruß und die damit verbundene Partikelemission bei Ottomotoren sind auf eine unzureichende Kraftstoffverdampfung während der Gemischbildung zurückzuführen. Um dies zu vermeiden, müssen Vorgänge der Kraftstoffeinspritzung, Sprayverdampfung und Durchmischung mit der Brennraumluft gezielt aufeinander abgestimmt werden. Dieser B...

The invention relates to a method for evaluating the state of a fuel/air mixture and/or the combustion in a combustion chamber of an internal combustion engine, with sample signals of flame light signals, preferably the flame intensity (FI), with associated mixture states being saved to a database, with flame light signals, preferably the flame lig...

We report on essential design elements of optically accessed research engines and describe selected examples of their applications in engine development. Whereas research topics most often address specific generic topics and are focused on comprehensive analysis of selected engine phenomena, the priority in using optical engines for engine developm...

We report on essential design elements of optically accessed research engines and describe selected examples of their applications in engine development. Whereas research topics most often address specific generic topics and are focused on comprehensive analysis of selected engine phenomena, the priority in using optical engines for engine developm...

Pressure measurement is as old as the development of internal combustion engines themselves. A confirmation of this can be seen in Fig. 3.1, which shows a cylinder pressure profile recorded with a mechanical indicator by August Nikolaus SI on 18th of May, 1876. This moment in time is often considered to be the starting point of the historical devel...

We have developed an optical measurement technique with a very high spatial and temporal resolution that allows the analysis as well as quantification of emitted shock waves and aggressive cavities that cause erosion. By a pulsed transmitted light technique with an exposure time of 15 ns the collapse of either single bubbles or cavitation clouds ca...

Gasoline engine development has to respond to requirements for fuel efficient and clean combustion. In meeting such targets, the automotive industry has responded with the introduction and continuous improvement of turbocharged gasoline direct injection (TC GDI) combustion systems. Specific challenges to such engines include irregular ignition and...

The miniaturization of hydraulic systems together with ever increasing static and dynamic fluid pressure as is happening in fuel injection systems leads to complex flow effects with very high local and temporal pressure gradients. System optimization for hydraulic efficiency, components durability or spray formation quality needs the understanding...

Gasoline engines have perfect emissions quality in stationary part load operation — how to ensure such ideal operation also at engine start, at tip-in tip-out, and at full load conditions? Key to the solution of these issues is the optimum use of components for mixture formation, combustion and exhaust gas aftertreatment with the focus on actuator...

Gasoline direct injection and turbocharging are essential technologies to enable development and mass production of fuel efficient, clean and robust engines. Testing and refining the mixture formation system has been found to be at the center of GDI combustion system development. The paper describes the tasks related to selection of components and...

We present experimental and theoretical investigations of the spectral series 2 3P–n 3Q (n=3–10, Q=S, P, D, ..., n-1) in electric fields up to 1600 kV cm−1. Such fields cause—for n>6—shifts of the upper levels of the observed transitions which are larger than the separation between levels with different principal quantum numbers. The patterns belon...

Dieser Beitrag der AVL List GmbH beschreibt eine Messtechnik, mit der die Gemischqualität in jedem Zyklus und in jedem Zylinder eines Ottomotors bewertet wird. Emissionsrelevante Kalibrieraufgaben an Ottomotoren werden damit schnell und präzise durchgeführt. Die dafür verwendeten Sensoren, die Mess- und Bewertungsmethoden reihen sich in den vertrau...

AVL List GmbH presents a measurement technique which enables evaluation of mixture formation quality in order to support calibration of emissions relevant SI engine operation. The method is especially suited to identify individual cycles’ particulate emissions contributions at engine start and in transient operation. Sensors, signal recorders and s...

Developing and calibrating engines to meet emissions targets requires the optimum balance of all system components and their effects on mixture formation, combustion as well as gas and heat flux into the aftertreatment system. Composition and temperature of the exhaust gas need to be adapted to the system components behind. This article by AVL List...

Die Erfüllung der Emissionsgrenzwerte erfordert eine ganzheitliche Abstimmung von Vorgängen der Gemischbildung, Verbrennung und Belieferung des Nachbehandlungssystems. Das Abgas muss in Zusammensetzung und Temperatur an die Erfordernisse der nachgeschalteten Komponenten angepasst sein. Dieser Beitrag der AVL List GmbH beschreibt Geräte und Methoden...

Modern injection systems in engines operate at very specific conditions with different fuels at high pressure gradients, small nozzles sizes and during short temporal intervals. The complicated nature of the accompanying processes, such as cavitation and surface erosion at these conditions, needs some experimental data base for theoretical model ve...

The objective of the presented work was to investigate the effects of high pressure cavitating diesel flows similar to those in real diesel engines with common rail injectors. Accurate experimental information about the flow is necessary for further development of the numerical models for prediction of cavitation and subsequent erosive effects. A t...

A detailed experimental study of the surface erosion process due to cavitation of the high-pressure diesel flows was performed. The flow conditions and hydraulic geometry were selected similar to ones in the common rail engine equipment. The measurements were realised with a high-pressure optical throttle, which has an optical access into the area...

A set of optical methods was developed and applied for diagnostics of high-pressure diesel flows at stationary and transient conditions. The high-pressure equipment is based on the common rail pump and included an original optical throttle with optical access through sapphire windows into the flow discharge area. This equipment supports the inlet p...

Der Serienentwickler verschafft sich rechtzeitig Gewissheit darüber, ob das Potenzial des Brennverfahrens tatsächlich so ausgeschöpft wird, wie es Konzept und Zielsetzung verlangen. Weil Verfahrensmängel nicht nur zu schlechten Leistungs- und Emissionsdaten führen, sondern zuallererst ihre Spuren in der Art und Weise hinterlassen, wie eine Flamme b...

Engine series development gets fast and in-time confirmation if a combustion system is as exhaustively exploited as concept design and pre-development have promised. Combustion deficiencies not only compromise performance and emissions, they first of all leave noticeable traces in the signature of the flame. AVL’s Visiolution technology systems ena...

An interferometrical technique was developed and applied for measurements of density distributions of high pressure diesel flows in an optical throttle and nozzle under stationary and transient flow conditions. A spatial resolution of the density measurements up to 0.8 µm/pix and recording time of 400 ns of single image were achieved. The single-i...

The spatial and temporal features of ultraviolet laser light absorption and laser induced fluorescence (LIF) by diesel fluid were studied. On the basis of these data a new method for liquid high-pressure diesel flow and spray velocities was developed. A short UV laser pulse prepared as a spatially narrow light sheet is absorbed by diesel. The temp...

Fuel injection systems (FIS) for diesel engines aim at ever higher injection pressures as this has proven to effectively support emissions reduction strategies. Part of manufacturing FIS components for best practical use requires the thorough understanding of fuel flow behaviour and how the injection and spray formation process can be influenced by...

Throttle flow phenomena are documented for conditions before and after the start of cavitation. The throttle flow properties are described in the conventional way with data for mass flow versus pressure drop. Such hydraulic characterisation is in widespread use to assess flow properties of high pressure fluid systems. As cavitation areas start to r...

In der Entwicklung anspruchsvoller Verbrennungssysteme werden in zunehmendem Ausmaß Visualisierungsmethoden eingesetzt, um die theoretisch möglichen Potenziale eines virtuell voroptimierten Brennverfahrens auch zielstrebig im Motorenversuch realisieren zu können. In speziell adaptierten Versuchsmotoren haben sich dafür eine Reihe von optischen Mess...

Methods for optical access to combustion chambers of internal combustion engines are shown. The optical access is either maximized to allow application of complex optical diagnostic techniques while maintaining minimum necessary operability of the engine or engine components, or full engine operability is maintained while optical access and diagnos...

The methods and results of an experimental analysis of diesel fuel sprays and internal flow properties of diesel fuel are reported. The spray analysis describes the fluctuation and break-up phenomena of diesel sprays observed by time resolved spray shadowgraphy with a fast line camera. Spray core break-up, ligament frequency spectra and ligament ve...

A series of experimental studies of diesel spray and combustion characteristics was carried out using circular, elliptic and step orifices. The experiment was performed on a 3-litre single-cylinder engine with optical access. In the engine tests, an elliptic-orifice nozzle with an aspect ratio of approximately 2:1, and a step-orifice nozzle were co...

Die effektive Auslegung der Kühlung ist ein Arbeitsschwerpunkt der AVL List GmbH, um wichtige Ecksteine einer Motorenentwicklung wie Abgasemissionen, Kraftstoffverbrauch und Komponentenhaltbarkeit zu unterstützen und zu verbessern. Nicht zuletzt die immer höheren spezifischen Leistungen von Motoren, bei gleichzeitiger Forderung eines niedrigeren Ve...

Der vorliegende Beitrag stellt den Verfahrensablauf von drei einander ergänzenden Entwicklungstechniken vor, die auf optischen Indiziermethoden aufbauen und die bei AVL integrierter Bestandteil bei Entwicklungsarbeiten von DI-Ottomotoren sind: Injektoreigenschaften werden in Hinblick auf Strahlform und Strahlzerstäubung bei unterschiedlichen Zylind...

This contribution describes optical techniques to analyse mixture formation and flame propagation in combustion chambers of gasoline engines. The optical access to the combustion chamber is provided by windows which are inserted into the piston and liner of a standardised single cylinder engine. Full engine functionality is then achieved by mountin...

An experimental study has been made in an optically accessed research diesel engine to measure the influence of fuel injection proessure and nozzle hole diameter on spray penetration, spray cone angle, and flame liftoff distance. The experiments are documented with data for the fuel injection pressure, the rate of injection, rate of heat release, a...

The development of engine combustion systems aims at exploiting the targets set by thermodynamics within the constraints of practical mechanical systems. This, in particular, involves the supply of a combustible mixture, its ignition and combustion. The fluid dynamic and thermo-chemical processes involved therein must be controlled in a way to prov...

The paper describes the design of a single cylinder base engine which provides optical access to the combustion chamber via glass cylinders and a piston with a glass crown. The application of this engine to the visual analysis of gasoline mixture formation and combustion is demonstrated with examples given for two- and four-valve cylinder heads. Th...

Combustion in a propane/air burner is analyzed by means of imaging molecular constituents present in the plane of a laser light sheet and by recording the local refractive index distribution with a shearing interferometer. The pulsed illumination with a UV light sheet yields an instantaneous image of the distribution of propane by elastic scatterin...

Fuel distribution in gasoline engines has significant influence on the cyclic stability of charge ignition and combustion, and hence on engine performance parameters related to the variation of combustion and heat release. There are numerous ways to influence in-cylinder fuel distribution by means of mixture preparation systems, engine aspiration o...

A current strategy in the development of direct injection (DI) diesel engine combustion systems is the control and limitation of the initial ‘premixed’ combustion heat release ensuing from the auto-ignition of the injected fuel. This requires control of the amount of fuel vaporization and mixing taking place during the ignition delay time. Since th...

Two optical techniques are presented which provide qualitative and semi-quantitative data about the distribution of fuel sprays in an optically accessed diesel research engine. The space and time resolved average distribution of fuel sprays is investigated with a light extinction method. A dual beam co-axial arrangement using visible and infrared H...

Light scattering and light absorption of hydrocarbon fuels was utilized to gain information about the presence and the space-time distribution of liquid and vaporized fuel inside the combustion chambers of optically accessed research engines. The design and application of the experimental method is described. In this paper, semiquantitative results...

A program of development and experimental validation of a multidimensional spray prediction method, based on the discrete droplet model, has been broadened to include computational investigations of the effects of random perturbations of the injection velocity on the spray characteristics, and further detailed examination of the spray structure and...

The paper describes the development and initial testing of a two-component backscatter Laser Doppler Anemometer for measuring spatial velocity scales. The effects of the number-of-samples, coincidence time and data rate upon the correlation coefficient are examined. Measurements of both the transverse and longitudinal correlation coefficients are m...

A primary breakup model has been developed based on locally resolved properties of the cavitating nozzle flow. According to this model the turbulent length scale determines the droplet size. A mixed aerodynamic/turbulent approach is used to calculate the break-up rate. The droplets are released from the surface of a coherent liquid core calculated...