Keywords

Air-breathing propulsion, multiphase flows, fuel injection, liquid jet in crossflow, ultrasonics, combustion

Abstract

The liquid fueling methods used in aircraft propulsion have undergone extensive optimization, with Liquid Jets in Crossflow (LJIC) emerging as a simple yet effective injection scheme. LJIC enables sufficient fuel mass flow rates and penetration for high-speed operation, however fuel trajectory and droplet size remain highly sensitive to crossflow conditions. As a result, wide flight envelopes introduce variability in atomization, leading to unsteady combustion performance. Recent work has incorporated a pintile, a solid obstruction placed in the path of the fuel jet, to redistribute momentum and reduce trajectory variability across varying flow conditions. While this approach improves trajectory uniformity, it does not significantly reduce droplet size. To address this limitation, a novel ultrasonically excited pintile-assisted LJIC injector was developed, combining the trajectory control of the pintile with acoustic excitation to enhance atomization. Mie scattering and phase Doppler interferometry were used to characterize jet breakup of a kerosene flow interacting with the ultrasonically excited pintile, while CH* chemiluminescence was employed to assess combustion performance. Relative to a stationary pintile configuration, the ultrasonically excited injector reduced breakup length and droplet size across both low and high Weber number conditions. Chemiluminescence analysis further revealed reduced variability in flame structure, increased effective flame speed, and extended lean blowout limits at lower equivalence ratios. These results demonstrate that ultrasonic excitation in pintile-based LJIC injectors enhances atomization and improves combustion performance for advanced air-breathing propulsion systems.

Completion Date

2026

Semester

Spring

Committee Chair

Ahmed, Kareem

Degree

Master of Science in Aerospace Engineering (M.S.A.E.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Format

PDF

Document Type

Thesis

Identifier

DP0053290

Download

Share

COinS
 

Accessibility Statement

This item was created or digitized prior to April 24, 2027, or is a reproduction of legacy media created before that date. It is preserved in its original, unmodified state specifically for research, reference, or historical recordkeeping. In accordance with the ADA Title II Final Rule, the University Libraries provides accessible versions of archival materials upon request. To request an accommodation for this item, please submit an accessibility request form.