Thrust and Specific Impulse Optimization of Eight-Centimeter Valveless Pulsejets at Low Subsonic Flight Speeds

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Title: Thrust and Specific Impulse Optimization of Eight-Centimeter Valveless Pulsejets at Low Subsonic Flight Speeds
Author: Boyette, Wesley Ryan
Advisors: Dr. William Roberts, Committee Chair
Dr. Terry Scharton, Committee Member
Dr. Andrey Kuznetsov, Committee Member
Abstract: The purpose of this research was to develop a method of accurately measuring the thrust and specific impulse of valveless pulsejets that are approximately eight centimeters in length. Previous methods of doing such were largely unsuccessful. A vertically arranged thrust stand and electronic balance were ultimately able to produce reliable results. Seven inlets were then tested on a forward facing arrangement. The maximum thrust achieved was 24.4 mN and specific impulse peaked at 295 seconds. Comparison revealed that increasing inlet length has a positive effect on pulsejet performance. Each inlet was tested at simulated forward flight speeds as well, showing that shorter inlets perform optimally at lower speeds than longer inlets. Additionally, a relationship between pulsejet performance, frequency and exhaust temperature was identified. Similar tests were performed on hybrid configurations as well, which combine forwardfacing and rearward-facing inlets. Of the five hybrid configurations tested, maximum thrust was 31.2 mN and maximum specific impulse was 232 seconds. This series of tests revealed that these configurations also showed improvement in performance at higher forward flight speeds and at smaller inlet areas. In all cases, hydrogen was used as the fuel, due to its very short chemical time. Pulsejets at this scale are also shown to be capable of operating on acetylene, although with reduced performance.
Date: 2008-12-02
Degree: MS
Discipline: Aerospace Engineering
URI: http://www.lib.ncsu.edu/resolver/1840.16/43


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