Helmut Pucher

Characterization of Combustion and NO Formation in a Spray-Guided Gasoline Direct-Injection Engine using Chemiluminescence Imaging, NO-PLIF, and Fast NO Exhaust Gas Analysis

The spatial and temporal formation of nitric oxide in an optical engine operated with iso-octane fuel under spray-guided direct-injection conditions was studied with a combination of laser-induced fluorescence imaging, UV-chemiluminescence, and cycle resolved NO exhaust gas analysis. NO formation during early and late (homogeneous vs. stratified) injection conditions were compared. Strong spatial preferences and cyclic variations in the NO formation were observed depending on engine operating conditions. While engine-out NO levels are substantially lower for stratified engine operation, cyclic variations of NO formation are substantially higher than for homogeneous, stoichiometric operation.

Development and Evaluation of a High Resolution Turbine Pyrometer System

Optical pyrometers provide many advantages over intrusive measuring techniques in determining the spatial and time varying temperature distribution of fast rotating components in gas turbines. This paper describes the development and evaluation of a versatile high resolution pyrometer system and its application to radial turbine rotor temperature mapping as has been done in a R&D project at the Technical University Berlin under funding from Siemens Power Generation (KWU). The development goal was a pyrometer system with a temporal resolution of 1μs, a minimum field of view of 1 mm, and a measurement range from 600 to 1500°C. A prototype of the pyrometer system has been built and tested at the small gas turbine test facility of the Technical University Berlin. The system yielded excellent results with respect to measurement uncertainty, resolution, and reliability. Finally, measurement results obtained with the new system on a radial turbine rotor and on a heavy duty industrial gas turbine are compared with measurements conducted with a commercially available turbine pyrometer system.© 2001 ASME

Steigerung des Wirkungsgrads von Ottomotoren Durch eine Abgaswärmegetriebene Kälteanlage

Eine viel versprechende Moglichkeit, die Abgaswarme sinnvoll zu nutzen, besteht im Antrieb einer Kalteanlage. Diese kann zur Kuhlung der Ladeluft unter Umgebungstemperatur eingesetzt werden. Durch den hierdurch vergroserten Abstand von der Klopfgrenze konnen aufgeladene Ottomotoren mit wirkungsgradgunstigeren Werten fur Verdichtungsverhaltnis und/oder Zundzeitpunkt betrieben werden. Im FVV-geforderten Projekt Heat2Cool (Nr. 965) befasst sich die TU Berlin mit der Erarbeitung des Potenzials und der Umsetzung dieses Konzepts.

Development and Evaluation of a High-Resolution Turbine Pyrometer System

Optical pyrometers provide many advantages over intrusive measuring techniques in determining the spatial and time varying temperature distribution of fast rotating components in gas turbines. This paper describes the development and evaluation of a versatile high-resolution pyrometer system and its application to radial turbine rotor temperature mapping as has been done in a R&D project at the Technical University Berlin under funding from Siemens Power Generation (KWU). The development goal was a pyrometer system with a temporal resolution of 1 μs, a minimum field of view of 1 mm, and a measurement range from 600 to 1500°C. A prototype of the pyrometer system has been built and tested at the small gas turbine test facility of the Technical University Berlin. The system yielded excellent results with respect to measurement uncertainty, resolution, and reliability. Finally, measurement results obtained with the new system on a radial turbine rotor and on a heavy duty industrial gas turbine are compared with measurements conducted with a commercially available turbine pyrometer system.

Gas Exchange and Supercharging

Beginning at the conclusion of the expansion stroke, the gas exchange phase basically performs two functions, namely: – replacing the utilized cylinder charge (exhaust) with fresh gas (air in a diesel engine), a basic prerequisite for an internal combustion engine, and – dissipating the heat as required to conclude the thermodynamic cycle.

A Unique Small Gas Turbine Test Facility for Low-Cost Investigations of Ceramic Rotor Materials and Thermal Barrier Coatings

The paper describes a test facility for small-scale gas turbines, which basically has been designed and assembled at the Institute of Combustion Engines of the Technical University Berlin. The facility exposes ceramic rotor components to the most significant loads that occur during real gas turbine operation in a clearly predefined manner (high circumferential velocities and highest turbine inlet temperatures). The test facility allows the investigation of bladed radial inflow turbine rotors, as well as — in a preceding step — geometrically simplified ceramic or coated metallic rotors. A newly designed, ceramically lined, variable geometry combustion chamber allows turbine inlet temperatures up to 1450°C (2640 F). A fast thermal shock unit (switching time of about 1s), which is integrated into the test facility between the combustion chamber and the turbine scroll, can be used to create, for example, severe transient temperature gradients within the rotor components to simulate gas turbine trip conditions. In order to generate steady state temperature gradients, especially during disk testing, the rotor components can be subjected to an impingement cooling of the rotor back face (uncoated in case of TBC-testing). The test facility is additionally equipped with a non-contact transient temperature measurement system (turbine radiation pyrometry) to determine the test rotor surface temperature distribution during operation. Apart from the possibilities of basic rotor material investigations, the test facility can also be used to automatically generate compressor and turbine performance characteristics maps. The latter might be used to assess the aerodynamic performance of bladed ceramic radial inflow or mixed flow turbine rotors with respect to manufacturing tolerances due to near-net-shape forming processes (e.g., gelcasting or injection molding).Copyright

Ladungswechsel und Aufladung beim Dieselmotor

Der Beitrag befasst sich eingangs mit den Grundlagen des Ladungswechsels von Viertakt- und Zweitaktmotoren. Dazu zahlen die Ladungswechselkenngrosen, die Arten der Steuerorgane (Ventile, Schlitze), die Wahl der Steuerzeiten, die Berechnung des Ventildurchflusses und die Zweitaktspulverfahren. Auch auf das Potenzial variabler Ventilsteuerungen wird eingegangen. Der Abschnitt Aufladung beschreibt das Zusammenwirken von Motor und Lader, mit dem Schwerpunkt Abgasturboaufladung. Dabei geht es um Stos- und Stauaufladung, ein- und zweistufige Aufladung und Turbocompounding. Ein Einblick in die Verfahren und Moglichkeiten der Ladungswechselberechnung schliest den Beitrag ab.

Increased gasoline engine efficiency due to an exhaust heat-driven cooling system

Charge air cooling below ambient temperature by an exhaust heat driven cooling system provides a promising approach to engine waste heat recovery. Due to decreased knocking probability at these conditions gasoline engines can be operated with increased compression ratio and/or advanced ignition timing to increase engine efficiency. The FVV project Heat2Cool (No. 965) conducted at TU Berlin investigates the potential and implementation possibilities of this concept.

Valve train optimisation using cycle simulation

Variable valve trains play an important part in enhancing engine efficiency. In order to gain maximum benefit from this, thorough concept optimisation has to be carried out in advance. This task is ideally performed by means of engine simulation.

A fuzzy-based optimisation algorithm for the online calibration of common rail injection systems

This article by the Technical University of Berlin presents a knowledge-based approach for the online optimisation of the engine control maps of common rail diesel engines. Unlike the hill climbing methods usually used for numerical optimisation, the knowledge-based fuzzy optimiser works by interpreting already known expert knowledge of the internal combustion engine under investigation. For this purpose, a set of engine-specific linguistic rules stored in a so-called fuzzy rule base are interpreted by the optimiser depending on the actual fuzzy input figures. The investigations were carried out as part of a research project supported by the Deutsche Forschungsgemeinschaft e.V.