Ph.D. Thesis Proposal

J. Richard D'cruz

(Faculty Advisor: Professor Dimitri Mavris)

Slosh Mitigation Methodology Development for Cryogenically-Fueled Fixed-Wing Aircraft Missions During Transient Maneuvers

Monday, July 13

8:00 - 9:00 a.m.

Weber, CoVE

Abstract: 

With the increased interest in reducing emissions in the aviation industry, it is expected that cryogens will have a larger share as energy carriers in future propulsion systems for atmospheric flight missions. Due to differences in their physical chemistry, cryogenic propellants will impose new aircraft design requirements, especially on fuel storage and fuel delivery. It is highly likely that due to relatively lower volume densities, cryogenic fuel tanks will be located exclusively in the fuselage.

While such large-volume propellant management is routine for spacecraft missions, the complex underlying phenomena such as slosh and boil-off have not been studied extensively for fixed-wing missions. Since spacecraft missions and fixed-wing missions differ in their scope, timescales and trajectories, it is necessary to study the impact that these phenomena will have on the vehicle performance. It is expected that cryogen slosh during and at the end of maneuvers can cause large loads leading to fatigue, cracks, excite unstable dynamic modes and, may also lead to higher rates of cryogen boil-off.

It is apparent that the existing slosh mitigation methodologies used in the transportation industry are biased towards passive control methods that may be unable to adapt to the changing flight dynamics unique to fixed-wing maneuvers. Therefore, a new methodology is needed to improve the overall effectiveness of cryogenic fuel storage pertinent to flight maneuvers. This research proposes an alternate methodology, by leveraging the unresolved physics that the underlying strategies of legacy methodologies are unable to exploit.

First, a general formulation of the cryogenic fuel management problem is defined. Using a coupled-dynamics model of the vehicle and the cryogen tank, the effects of fuel slosh through various fixed-wing maneuvers are investigated and quantified. The significance of the effects of slosh on cryogen boil-off is studied. Analyses are performed against baseline smooth-bore tanks and tanks equipped with legacy slosh suppression strategies.

Second, candidate active control strategies for slosh suppression are explored. Metrics for evaluating the alternatives are then developed to compare the effectiveness of the strategies. These metrics are used to determine which technologies meet the feasibility requirements to solve the problem. The control strategy is then implemented on the coupled-dynamics model and evaluated against the baseline legacy case to assess the trade-offs in maneuver performance.

Finally, a control strategy that augments the legacy technology with the active control strategy is proposed to address the cryogenic fuel management problem and will be demonstrated by evaluating its maneuver effectiveness.

Committee:

Dr. Dimitri Mavris (advisor), School of Aerospace Engineering
Jonnalagadda Prasad, School of Aerospace Engineering
William Singhose, School of Mechanical Engineering
Christian Perron , School of Aerospace Engineering