Steven P. Nichols

Use of Fractal Geometry to Model Turbulent Combustion in SI Engines

Abstract Use of fractal geometry to model the effects of turbulence on flame propagation in an engine is explored using a quasidimensional, 4-stroke, homogeneous charge, SI engine code. This application of fractal geometry requires a new interpretation of the effect of turbulence on the combustion process in an engine. Specifically, flame wrinkling, rather than entrainment, is assumed to be the dominant effect of turbulence on the combustion process. Various simplifications are made in the formulation of the engine model to allow this fractal technique to be investigated as expeditiously as possible. Model predictions are compared to experimental data from an engine with an axisymmetric pancake-shaped combustion chamber. The sensitivity of the model predictions to the fractal dimension, to the effects of flame stretch, and to the ratio of maximum-to-minimum flame wrinkling scales is investigated. It is shown that the predicted initial rate of pressure rise is a strong function of the fractal dimension but...

Special session — Henry's Daughters: A new Engineering Ethics movie

The National Institute for Engineering Ethics has produced a new movie, Henrys Daughters, to aid in teaching professional ethics in engineering. The movie highlights ethical issues at both individual and societal levels. In this special session, participants will learn how to use two cooperative learning strategies together with the new movie. Participants will also learn a classroom assessment technique.

Incident at Morales: an engineering ethics video

The National Institute for Engineering Ethics has produced a new video that dramatizes a fictional but realistic case in which an engineer addresses numerous ethical issues in designing a new chemical plant in Mexico. In a special session at the conference, participants will learn to use a new video to teach professional and ethical issues in engineering effectively, with two basic cooperative learning techniques: generating questions in pairs and structured discussions in small groups.

Design and analysis of the tracker bridge for the Hobby-Eberly Telescope* wide field upgrade

A large structural weldment has been designed to serve as the new star tracker bridge for the Wide Field Upgrade to the Hobby-Eberly Telescope at McDonald Observatory in support of the Hobby-Eberly Telescope Dark Energy Experiment‡. The modeling approach, analysis techniques and design details will be of interest to designers of large structures where stiffness is the primary design driver. The design includes detailed structural analysis using finite element models to maximize natural frequency response and limit deflections and light obscuration. Considerable fabrication challenges are overcome to allow integration of precision hardware required for positioning the corrector optics to a precision of less than 5 microns along the 4-meter travel range. Detailed descriptions of the bridge geometry, analysis results and challenging fabrication issues are discussed.