PhD Defense by Amanda Grubb
(Advisor: Marilyn Smith)
will defend a doctoral thesis entitled,
Computational Investigation of Separated Flow and Stall Events on Rotating
Wednesday, April 13 at 10:00 a.m.
Helicopters have traditionally been largely associated with military use. Over the past decade,
new and diverse commercial applications have been discovered for vehicles that can
takeoff/land vertically and achieve mid-flight hover. The need for a new military rotorcraft
fleet, coupled with the explosion of potential commercial applications, has created a sense of
urgency in developing next generation rotorcraft with improved speed, range, and agility.
Rotorcraft are highly complex, dynamic vehicles with aeromechanics that are conducive to
challenging problems. Many problems encountered by rotorcraft are a result of flow
separation on the rotor. Increased speed, range, and agility requirements will only exacerbate
these effects. Understanding flow separation on the rotor plane and the effects it has on the
vehicle is fundamental to solving problems facing the next generation of rotorcraft
development. The best approach to fully understand flow separation on the rotor plane is
through a combination of experimentation and computational fluid dynamics.
This dissertation couples high fidelity CFD with trusted experimental data sets to create a
complete picture of rotorcraft flowfields for study. State-of-the-art CFD modeling techniques,
many of which have not been addressed recently, are evaluated to identify and quantify their
capabilities and limitations. This includes grid refinement approach, numerical approach,
turbulence model effectiveness, and aeroelastic coupling bias. Rich flowfield data from CFD,
coupled with experimental data, are explored to further understand separated flow on the
rotor and its effects on rotorcraft performance. Separated flow is classified by separation
mechanism via isolation of blade motion from shed tip vortices. Dominant flowfield vortices
are studied to understand their impact on rotor performance using the Biot-Savart Law.
• Mr. Rohit Jain
• Dr. Juergen Rauleder
• Dr. Christina Riso
• Dr. Daniel Schrage