Influence of dynamic motions on the flow physics of a tailless chine-forebody slender delta wing aircraft
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Authors
Remneff, Paul
Issue Date
2025-12
Type
Electronic thesis
Thesis
Thesis
Language
en_US
Keywords
Aeronautical engineering
Alternative Title
Abstract
At moderate to high angles of attack, delta wing aircraft develop vortices over their wingsthat form at the sharp leading edge. The vortex formation over a chined-forebody delta
wing aircraft is affected at different pitch, roll, or yaw angles. Differences between static and
dynamic motions on vortex development were also observed. Experimental wind tunnel tests
conducted at a Reynolds number of Rec = 2.53 × 10^5 using strain gauge load balance showed
how the aerodynamic loads were impacted by different maneuvers and aircraft attitudes.
Changes observed in loads were then correlate the changes in the flow field using stereo
particle image velocimetry data. The results show that at angles of attack α > 28◦, the
model experienced an asymmetric vortex breakdown, causing a decrease in the lift and drag,
as well as a pitch moment and roll moment. Increasing a roll or yaw angle can further decrease
the overall lift and drag at these higher angles (α > 25◦), while further compounding the
asymmetries led to an increase in side force, roll moment, and yaw moment. Performing
dynamic pitch, roll, and yaw motions at low angles of attack (α < 25◦) showed negligible
hysteresis in the forces or moments, while similar dynamic motions performed at α > 25◦
showed larger hysteresis loops. From the SPIV data, it was concluded the hysteresis was
caused by a delay in breakdown during dynamic pitching up or increasing the roll angle, while
pitching down or decreasing the roll angle promoted breakdown. The changes in the axial
velocity and the circulation were evaluated to quantify the effects of the dynamic motions
on the flow field. A decrease in the axial velocity within the vortex, as well as a decrease in
the circulation was calculated in most of the dynamic cases compared to the corresponding
static case.
Additional SPIV work was conducted to observe how a synthetic jet interacted with
a steady vortex for possible flow control applications. A rectangular orifice synthetic jet
was placed downstream of a vortex generator. The jet orifice was pitched downstream, and
skewed by 45◦ with respect to the freestream to generate a vortex that would augment the
steady vortex. The synthetic jet was operated at two blowing ratios of C_b = 1.0 and C_b = 0.5.
The location (relative to the synthetic jet) and height of the vortex generator was also varied
from 1δ, 2δ, or 3δ with respect to the local boundary layer height at the vortex generator
location, while the spanwise location was adjusted from z/δ = 0 − ±1.3 with respect to the centerline of the synthetic jet. Results showed that the synthetic jet was able to forma streamwise vortex downstream even in the absence of the vortex generator. When the
vortex generator was placed at the center or closer to the side the synthetic jet was facing,
the steady vortex and the vortex from the synthetic jet compounded and formed a larger
vortex with higher vortex core velocity. However, when the vortex generator was placed at
the side the synthetic jet was facing away from, separate vortices remained downstream, that
were comparably weaker. A stronger synthetic jet, with C_b = 1.0, had greater influence over
the interactions. However, for the smallest 1δ vortex generator, that formed a weaker and
smaller streamwise vortex, the synthetic jet destroyed it and only the structures from the
synthetic jet propagated downstream.
Description
December2025
School of Engineering
School of Engineering
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY