Development of a Small Project on Spray Combustion for an Undergraduate Fluid Dynamics Class

Abstract

Abstract This work describes the development and evaluation of short project on spray combustion for a junior-level fluid dynamics course. A perennial question heard by educators in the United States is “When am I ever going to use this?” The standard format of most engineering courses involves lecturing students on various topics in mathematics and sciences related to their engineering discipline. Often students are not asked to apply the knowledge of said sciences in an engineering focused context until a capstone senior design course. In the mean time, students in freshman, sophomore, and junior courses become demotivated by the often dry nature of the theoretical focus. Evidence suggests that use of short projects and cases studies in the engineering classroom promotes motivation for the subject material. Some evidence also suggests that such motivation improves student learning outcomes. Accordingly, the development of such projects is important. This project focuses on topics that are often left out of the undergraduate engineering curriculum: combustion and two phase flows. These topics are major areas of interest for research in the automotive and aerospace industries, and are especially important for the design of engines for said vehicles. However, their discussion is often restricted to graduate courses if discussed at all. This project will introduce students to said topics in a novel context associated to applications in their field. The project focuses on spray combustion because it is an important phenomenon in aviation gas turbine engines. The standard description of combustion in that context is as follows. First, the liquid fuel is injected into the engine where it is broken down into small droplets. The droplets vaporize, and the resulting fuel vapor mixes with the air around it. Combustion occurs for the fuel-air mixture, and energy is released as heat. For this project, students will engage with these processes at a cursory level using the tools of the fluid dynamics class. The project focuses on developing the students’ skills in control volume analysis, potential flows, and similitude. These topics roughly correspond to one of three major modules in the fluid dynamics course, and accordingly the project also serves as a mini-capstone for the module. The project divides students into small teams. Each team of students is tasked to design a combustor according to certain mission constraints which are varied between teams. Project evaluation is performed by a survey of the students after the project is completed. The goal of the survey is to assess student opinions of the project including its effects on student motivation in the class and learning of the class material. This initial study focuses on gaining insight to improve the project design for future semesters.