T. KORAKIANITIS Piston assembly dynamics	"Korakianitis" is pronounced phonetically
email: tk@mecf.wustl.edu	link: [ 183 kB audio wav]

May 1999 -

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Research in piston engines	Research in turbomachines	Engineering practice	Opinions on education
Internal combustion engines laboratory Emissions Combustion (you are here) Piston dynamics Valve train dynamics Nutating-disk engine Turbochargers	Airfoil and blade design Stator-rotor interactions Aircraft inlets Combustion Emissions Gas-turbine transients Gas-turbine performance	Machine design topics Thermofluids design Blood flow in human heart Surgical instruments Power generation Aeronautical applications Piston engines	Graduate thermodynamics (ME 512) Graduate piston engine design (ME 578) Graduate turbomachinery design (ME 574) Senior design course (ME 404/404a/404b) Junior thermodynamics (ME 320A) Freshman internal combustion engines (ME 147)

Archival publications

Do your numerical computations on one-piece and two-piece (articulated) pistons match experimental observations or engine experience? What numerical integrator are you using? Your computations may be converging in what appears a correct periodic solution, but does that solution represent nature? If not, why not? How can you be sure? How can you improve your model to compute what experiments tell you you should be computing?

HOW DOES ALL THIS AFFECT ENGINE EMISSIONS?

The figure shows converged computations with implicit and explicit integrators for a journal bearing with eccentric mass. For this case there is an analytic solution with which we can compare. The performance of explicit Euler solvers... Our solver predict the correct trajectory with crank-angle increments (time steps) from less than 1 degree and up to 120 degrees. We need to limit the time step in order to resolve the trajectory rather than accuracy or stability of computation. How does your numerical computation compare?

Include here two or three figures from journal bearings showing integrator performance. Delete from figures any hints on what is the suitable integrator.

Our models for piston dynamics include:
one and two-piece piston geometries with various eccentricities;
cylindrical and non-cylindrical pistons;
lubricant-cavitation models on the piston skirts;
dynamic models with one or two corners impacting or scraping the liner;
the effect of surface asperities; and
other aspects not available in the literature.

Include here the figures of one and two-piece piston, six figures of H(i) from a two-piece piston with scrapes and impacts, and one figure of pressure on skirt with lubricant cavitation.

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