No abstract

Theoretical results on gaseous convective turbulent diffusion in steady axisymmetric flows are found to compare well with experimental results already in the literature. The investigation starts with the formulation of a highly idealized “slug-flow” model of the process for a quick estimate of the importance of turbulent boundary layer convection and for a comparison of previously published experimental and analytical results which had revealed order-of-magnitude discrepancies between calculated and measured air diffusion rates. Next, an existing two-dimensional convective diffusion model is adapted to axisymmetric cavity flow. Good agreement between experimental and calculated mass flow rates is found with a proper choice of turbulent diffusively from a Launder-Spaulding mixing-length model. The adapted “wrap around” model predicts a concentration boundary-layer thickness of the order of the cavity radius at the cavity terminus. Consequently, an axisymeetric analysis is also presented. From this it is found that the important part of the gaseous mass flow into the cavity occurs near the very front of the cavity where the concentration gradients are most severe. Downstream flow regions near the cavity are thereby depleted of dissolved air and the resulting concentration gradients are greatly reduced. Therefore the mass flow rate through downstream cavity surfaces are relatively unimportant and the simpler wrap around calculation can give useful engineering estimates of total mass flow rates.

in 1978 and worked in the aerospace industry (mostly in flight simulation) full-time up until returning to academia in 1992. He received his M.S. in AE in 1994 and became full-time faculty at Parks in 1995. Lawrence still retains part-time status in industry. Lawrence has varied hobbies including flying (private pilot), church choir directing, pipe organ restoration and playing, various types of dancing and Contra Dance calling.

This paper gives an analysis of convective gaseous diffusion into a full cavity behind an oscillating flat-plate hydrofoil in a turbulent flow. The unsteady diffusion theory accounts for fluctuations of cavity gas pressure and length which are assumed to be harmonic oscillations but are not necessarily in phase with the hydrofoil motion. A diffusive lag function is found which, for a given reduced frequency, determines the instantaneous diffusion rate as a product of the lag function and the quasisteady mass diffusion. The present results can be used to study the rate of gas entrainment from the cavity into the wake behind the oscillating cavity.

A basic shop course was typical in the early days of mechanical engineering studies. However, in the late seventies, the shop course was dropped from the engineering curriculum in most schools for various reasons. The need for a preparatory manufacturing course became apparent after recognizing the lack of modest shop skills exhibited by our students in design-build projects which are routinely assigned in several junior and senior level courses. The traditional manufacturing course, that all students are required to take during the senior year, requires higher-level prerequisites. In addition, being a senior level course, it provides very little opportunity for the students to utilize those skills in other courses. To address this void, a new engineering workshop course has been objectively designed and implemented for the sophomore mechanical and aerospace engineering students, beginning fall 2003. The goals of the course are to develop an appreciation for manufacturing in engineering design, prepare students for follow-up manufacturing course, and develop necessary skills for design-build projects at various levels of the curriculum. The engineering shop course is designed around nine laboratory content modules that introduce the students to the fundamentals of shop safety, measurement, and manufacturing. The present paper describes the development and implementation of the course. The effectiveness of the course in meeting the goals is also assessed through surveys conducted both before and after the course is completed. Long-term success will be measured in the future by a survey of graduating seniors to assess the effectiveness of the engineering shop course in the students’ ability to successfully complete design-build projects assigned in other courses. The modular design would allow this course to be adapted for achieving similar objectives elsewhere.