Olaf Toedter

A simple laser-based distance measuring device

Abstract We report on a simple laser-based sensor for distance, velocity and shape measurements. The distance between the sensor and the measurement object is evaluated by a new triangulation principle. A laser beam providing a high spatial resolution is scanned across the measurement object. The triangulation angle is determined by means of a time difference measurement of reflected light focused on two different detectors. The measurement range covers several centimeters to some 10 m, the relative error of a single shot measurement is less than I I% and could be reduced by multiple shot measurements of less than 5%. The measurement repetition rate is up to 200 kHz depending on the emitted laser intensity and the evaluation circuit. Applications of the instrument in industry, quality control and traffic control are discussed.

Investigations on Spark and Corona Ignition of Oxymethylene Ether-1 and Dimethyl Carbonate Blends with Gasoline by High-Speed Evaluation of OH* Chemiluminescence

Bio-fuels of the 2nd generation constitute a key approach to tackle both Greenhouse Gas (GHG) and air quality challenges associated with combustion emissions of the transport sector. Since these fuels are obtained of residual materials of the agricultural industry, well-totank CO2 emissions can be significantly lowered by a closed-cycle of formation and absorption of CO2. Furthermore, studies of bio-fuels have shown reduced formation of particulate matter on account of the fuels’ high oxygen content therefore addressing air quality issues. However, due to the high oxygen content and other physical parameters these fuels are expected to exhibit different ignition behaviour. Moreover, the question is whether there is a positive superimposition of the fuels ignition behaviour with the benefits of an alternative ignition system, such as a corona ignition. To shed light on these questions two oxygenic compounds, oxymethylene ether-1 (OME1) and dimethyl carbonate (DMC) have been studied with respect to OH* emission throughout ignition and onset of flame-front propagation in a combustion chamber with a large optical access via a quartz window. OH* measurements have been recorded via a highspeed optical camera (5 kHz) coupled with 308 nm optical filter and image intensifier. Sealing material swelling tests have yielded a perfluoroelastomer (FFKM 72) as an ideal, cost-efficient material regardless of the applied fuel. Comparative measurements with both ignition systems for combustion of gasoline as well as moderate blend admixtures of OME1 and DMC have demonstrated the superior ignition stability with likewise implications on flame-kernel development for the corona ignition. Furthermore a strong influence of the mode of discharge on OH* formation rates was observed especially for the oxygenic blends. Finally, for admixture variations of both oxygenates, an increased OH* level was shown during discharge thereby proving the hypothesis of a positive superimposition of oxygenic fuel and corona ignition system.

Der Einfluss des Dieselmotors auf die Luftqualität = Influence of Diesel Engines on the Air Quality

Der Dieselmotor ist in vielen Anwendungsbereichen unverzichtbar, kommt aber durch seine Emissionen immer wieder in Kritik. Mit moderner Abgasnachbehandlung konnen aber inzwischen die Stickoxid-Emissionen und die Partikelemissionen deutlich reduziert werden. Ein Blick auf die Immissionsbelastung der vom Dieselmotor verursachten Emissionen zeigt bereits, dass hier eine deutlichere Verbesserung stattgefunden hat.

Second generation ISS diesel cold start technology with pre-heated intake air

Market share in diesel engines has almost reached the 50 percent mark in Europe, and, in the USA, is increasing at a much more significant rate than that of petrol hybrids. Increasingly strict emission limits, coupled with endeavors to continue reductions in fuel consumption, are already indicating significant effects on future diesel engine design. Beru AG is taking account of this development with its enhanced Instant Start System (ISS).

An improved laser sensor for surface velocity measurement

A compact sensor for velocity, size and contour measurements in traffic and production control has been designed and tested. The sensor head consists of modulated laser diodes emitting two parallel eye-safe probing beams and a sensitive detection unit. The primary advantages are long-range reflectorless detection, high spatial resolution and low cost.

Impact of Non-Thermal Plasma on Particulate Emissions in Application in a Diesel Engine Exhaust Duct

Particulates and nitrogen oxides comprise the main emission components of the Diesel combustion and therefore are subject to exhaust emission legislation. Yet, with more stringent emission standards and test-procedures, such as in passenger vehicle applications, resulting exhaust gas after-treatment systems are complex and costly. Hence, new technologies for emission control have to be explored. The application of non-thermal plasma (NTP) as a means to perform exhaust gas after-treatment is one such promising technology. One way to generate a NTP is by a corona high-frequency discharge. Apart from few other publications dealing with NTP exhaust gas aftertreatment where a NTP was generated via dielectric barrier discharges (DBD), the experiments in this publication were conducted on an operated series-production Diesel engine with an industrial pilot-type corona ignition system. Originally developed as an alternative for a spark-plug system in SI engines its attributed properties, such as large penetrated volume and high radical concentration, may also be utilized in the exhaust gas stream as it has been done in this publication. To investigate the effects of a corona discharge on Diesel engine emissions, four igniters were integrated in the exhaust duct of a CRDI 2.0 liter engine equipped with DPF. The impact on particle number, size distribution as well as on nitrogen oxides has been studied for various operational parameters of the corona system. The particle number was measured downstream of the DPF to observe the level of improvement for remaining unfiltered nanoparticles. In this first series of tests, a reduction in particle number of up to 10 % was achieved depending on engine load. Particle size distribution was measured upstream of the DPF. In this case, the highest reduction of 10 % was observed in the mid-range particle size of about 60 nm. No increase in other particulate size ranges has been observed.

Comparing Visualization of Inflammation at Transient Load Steps Comparing Ignition Systems

The comparison of spark ignition systems and corona ignition systems is performed by changing a spark plug to a corona igniter in an existing engine configuration on an Engine-in-the-Loop test bed. In this investigation visual inspection of the inflammation is done comparing visible image with spectral resolved two-dimensional information investigating the for flame initiation relevant OH*, CH* and \({\rm C}_{2}^{*}\) chemiluminescence. A general comparison between optical and thermodynamic analysis is performed. The observations are then used to evaluate transient cycle-to-cycle comparisons of the two ignition systems.