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Design of an Endoscopic Fully Optically Accessible High-Speed Large-Bore Engine
- Stephan Bernhard Karmann - Technical University of Munich, Germany ,
- Hannes Röhrle - Technical University of Munich, Germany ,
- Bernhard Klier - Technical University of Munich, Germany ,
- Maximilian Prager - Technical University of Munich, Germany ,
- Georg Wachtmeister - Technical University of Munich, Germany
Journal Article
03-15-06-0042
ISSN: 1946-3936, e-ISSN: 1946-3944
Sector:
Topic:
Citation:
Karmann, S., Röhrle, H., Klier, B., Prager, M. et al., "Design of an Endoscopic Fully Optically Accessible High-Speed Large-Bore Engine," SAE Int. J. Engines 15(6):773-789, 2022, https://doi.org/10.4271/03-15-06-0042.
Language:
English
Abstract:
Rising engine efficiency and exhaust limitations demand a deeper knowledge of the
combustion process. State-of-the-art investigations use laser optical test
equipment that relies on optical accesses into the engine. In this article, a
new endoscopic, fully optical access for a high-speed large-bore engine is
demonstrated. The successfully realized concept consists of two individually
usable accesses: The lateral access with a vertical field of view is realized
via a ring, which is inserted between the cylinder liner and cylinder head. The
ring offers several screw-in positions for an ultraviolet (UV)-enhanced
endoscope. This access can be used independently for full-load investigations of
the mixture formation and combustion processes taking place inside the cylinder;
The second access from above is realized by inserting a self-developed fisheye
endoscope. The endoscope replaces one of the exhaust valves and supplements the
lateral access with a horizontal field of view covering nearly the whole
combustion chamber. The development of the optical design of the fisheye
endoscope using ray tracing is detailed for this type of all-optical engine. The
materials and design changes made for the second access reduce the convertible
engine load. Thus finite element method (FEM), conjugate heat transfer (CHT),
and multibody simulations validate strength and temperature behavior under
engine conditions. A similar concept was already implemented and successfully
tested at a dual-fuel engine with 40 l displacement. With the current
investigations, it is shown that this concept represents a reasonable and
feasible solution for in situ engine investigations for smaller engines as well,
here with a bore of 170 mm and a stroke of 210 mm resulting in a 4.8 l
displacement. For this reason, the design shown here approximately halves the
diameter of the fisheye optics compared to the design already implemented. The
main focus is thus on reducing the installation space of the optical accesses
while at the same time optimizing the optical imaging properties and the field
of view. The significantly reduced concept shown here, in turn, has the
possibility of being integrated more efficiently into an engine with a larger
displacement class through a reduced modification effort, thus simplifying the
in-situ investigations and enhancing the likeness to the original engine.