Joyce MO, Christopher GALEA, Michael PALUSZEK

DOI Number: N/A

Conference number: HiSST-2025-232

Airbreathing engines have been studied for improving the efficiencies of hypersonic propulsion systems, whereby all the needed oxygen for combustion is captured from the atmosphere as opposed to carried oxidizers. Airbreathing engines include turbojets, ramjets, scramjets, and dual-combustion ramjets. For a hypersonic, two stage to orbit
launch vehicle, turbo-ramjets have been proposed for the first stage to reach Mach 6.8, as seen in Germany’s Sanger II. Turbo-ramjets have also been flown successfully on the SR-71 Blackbird, which harnessed 2 Pratt & Whitney’s F58 turbojets and transitioned to ramjet behavior at Mach 2. Princeton Satellite Systems has been developing a smaller hypersonic, two stage to orbit launch vehicle called Space Rapid Transit for a 500 kg payload to LEO. Space Rapid Transit uses a dual-flow path turbofan-ramjet engine for the first stage to reach Mach 5 and 40 km altitude. This consists of 2 Pratt&Whitney F135 turbofans and 1 ramjet. The turbofans operate on jet fuel. The ramjet is designed for hydrogen fuel and is comprised of an inlet, a combustor, and a nozzle. For optimal ramjet behavior, the inlet needs to be designed to form a series of oblique shocks to sufficiently
compress the air flow to subsonic speeds for combustion in the combustor. As air passes through the inlet, it loses kinetic energy and increases in pressure. As the velocity of the vehicle increases, the oblique shock positions change, leading to off-optimal behavior for the operation envelope of the ramjet. Thus, ramjets are currently limited to Mach 3 to 6. Another challenge of the 2-turbofan and ramjet configuration for Space Rapid Transit is the controlled blocking of the incoming freestream airflow during transitions from the turbofans to the ramjets at Mach 1.2. Insufficient control may lead to inlet upstart, whereby shockwaves are expelled upstream out of the inlet aperture due to instabilities. This paper examines variable inlet geometry to improve upon the pressure recovery ratio of the ramjet inlet through SUPIN.

Read the full paper here

In Categories: 1.Events, 1.HiSST 2025, Propulsion Systems & Components
Email
Print
LinkedIn
The paper above was part of  proceedings of a CEAS event and as such the author has signed a publication agreement to have their paper published in the repository. In the case this paper is found somewhere else CEAS always links to the other source.  CEAS takes great care in making the correct content available to the reader. If any mistakes are found  in the listings please contact us directly at papers@aerospacerepository.org and we will correct the listing promptly.  CEAS cannot be held liable either for mistakes in editorial or technical aspects, nor for omissions, nor for the correctness of the content. In particular, CEAS does not guarantee completeness or correctness of information contained in external websites which can be accessed via links from CEAS’s websites. Despite accurate research on the content of such linked external websites, CEAS cannot be held liable for their content. Only the content providers of such external sites are liable for their content. Should you notice any mistake in technical or editorial aspects of the CEAS site, please do not hesitate to inform us.