S-duct inlet analysis and design for small turbojet applications

Abstract

This report outlines the process of designing an S-duct inlet for a JetCat PlO0-RX engine that satisfies the requirements of the 2020-2021 APOP design challenge. For the inlet design three design parameters were optimized. These are: axial length, capture area, and inlet geometry. Through the use of a moment arm test stand and mass flow rate parameter, a variety of inlets were tested on the JetCat engine with the goal being to minimize performance losses by changing the design parameters. These inlets were 3-D printed using a Creatbot F430 3-D printer. A testing matrix along with computational fluid dynamic simulations in the CAD software Solidworks was used in order to pinpoint the optimum inlet design. Experimental results for pressure recovery were evaluated utilizing a static pressure ring and Kiel probes for total pressure measurement. Experimentation indicated that the primary criteria of pressure recovery was negligible and decreasing axial length proved to have negligible effects as well so the capture area could be further decreased as all engine parameters, except potentially the SFC values, meet the requirements set out by AFRL. While there is some question as to the validity of the SFC, testing has demonstrated that a short inlet with two 90 degree turns will perform acceptably while maintaining a relatively small volume. Further testing and validation may need to be performed for the fmal inlet design choice as experimental results were not able to be obtained within the bounds of this project.