• Assembly of Turboprop without exhaust next to Jet Engine

  • Close-up view of Turboprop components assembly

  • Turboprop power turbine inlet view

  • CAD Model cross-sectionview

  • Full Turboprop working prototype assembly

  • Parts ligned up before assembly

  • Power turbine and gearbox assembly

  • Gearbox

  • Guiding vanes and coupler assembly, power turbine in the back

GenJet

Project Sponsor: Aerospace Propulsion Outreach Program (APOP)
Technical Advisor: Dr. Timothy B. Smith

PROJECT DESCRIPTION

The U.S. Air Force Research Laboratory’s (AFRL) Aerospace Propulsion Outreach Program (APOP) is sponsoring an intercollegiate competition that gives undergraduate students the opportunity to modify a JetCat P-80SE gas turbine engine. This year’s task is to design an attachment to a JetCat gas turbine that is capable of extracting 500 Watts of DC electrical power at 24 Volts while maintaining as much of the stock thrust as possible.

OJECTIVE

Extract 500 Wats of DC Electrical Power at 24V from a JetCat P-80SE gas turbine while mainting the stock thrust.

WORK

Our solution to the task presented by APOP was to convert the JetCat P-80SE jet engine into a turboprop engine and drive an alternator through a timing belt connected to the propeller shaft. To do so we use the JetCat as a gas generator, remove the nozzle and bolt on our designed power section add-on turboprop (Figure 1). This modular approach to building a turboprop is not currently used for full-size models.

Figure 1: CAD Model of turboprop add-on. Note the alternator is not include in this model.

We are harnessing the exhaust gases from the JetCat gas turbine and using them to drive a power turbine. By the time the gases pass the turbine there is little pressure left to create thrust. So, a propeller is coupled to the power turbine through a gear reduction train to generate thrust. The gear reduction train is required to convert the high RPM, low torque of the power turbine shaft to low RPM, high torque in the propeller shaft. The speed of the propeller has to be reduced to prevent efficiency losses if the tips of the propeller reach supersonic speeds. Further, high torque is required to pull sufficient air through to generate thrust. To generate the 500 W of electrical power required the propeller shaft will drive a timing belt connected to an alternator.

The add-on device is greatly influenced by the publicly available WREN MW54 Turboprop [1] design by WREN Turbines USA [2]. We have made substantial modifications to the design to meet our needs and manufacturing capabilities.

  • N. Alve, A. Dun, A. Kini, K. Patel, R. Shu, "Alignment Platform for Multilayer Soft Lithography". MechEng 450: Design and Manufacturing III Final Report, University of Michigan, 2013. [PDF]
  • N. Alve, A. Dun, A. Kini, K. Patel, R. Shu, "Alignment Platform for Multilayer Soft Lithography". MechEng 450: Design and Manufacturing III Design Expo, University of Michigan, 2013. [PDF]