Abstract:
Ground effect is a significant phenomenon that requires evaluation during the design
phase of any flight, particularly during take-off and landing. To ensure a successful
flight, careful consideration of this phenomenon is critical. Experimental testing is
typically done later in the design process due to complexity, time, and cost factors;
however, Computational Fluid Dynamics (CFD) is an alternative technique that
provides good accuracy in less time.
This research aims to study the aerodynamics and dynamic stability of the Blended
Wing Body (BWB) aircraft in close proximity to the ground. For this purpose, the
SACCON UCAV model is selected, and its static aerodynamics and dynamic stability
data have been validated to develop an accurate computational framework.
The numerical study is performed at five different non-dimensionalized heights (h/b)
near the ground, starting from value 0.2 to 1.0 for static aerodynamics. Three different
non-dimensionalized heights (h/b) are simulated for dynamic stability, starting from 0.8
to 1.0. Geometry has been created using CAD software and validated with experimental
data for steady and dynamic stability data. The grid has been generated in ICEM with
tri-tetra unstructured elements, and two different models (SA & SST-kw) have been
used for the validation study.
The results of the research demonstrate that observable effects are present in the flight
mechanics and steady aerodynamics when non-dimensionalized height (h/b) ≤ 0.2 and
the angle of attack (α) ≥ 15o
. This phenomenon in aerodynamic and stability
coefficients occurs due to the high-pressure region beneath the Small BWB (SACCON
UCAV) in close proximity to the ground. However, at low angle of attacks, the variation
in flight mechanics and aerodynamic characteristics is less than 1%. While ground
effect has a small impact on the pitch and roll dynamic stability of SACCON UCAV,
the pitch and roll dynamic damping coefficient does not vary considerably with changes
in height (h/b). Furthermore, no significant change in flow characteristics of SACCON
UCAV has been observed in pitch and roll dynamic simulations. The variation in
aerodynamic and dynamic stability coefficients is less than 5% for small BWB
(SACCON UCAV).
