Research at CeFPaC

The center has two main thrusts: (i) Aerodynamics of aerial, ground and underwater vehicles, (ii) wind energy (smart wind turbine blades, and buildings integrated wind).   

CeFPaC’s primary research areas include:

  • Flow Physics: 2-D, 3-D, and unsteady flows
  • Flow Control: Fundamental and applied experimental, numerical and theoretical investigations of flow control in macro and micro systems
  • Actuators: Design, fabrication, optimization, and modeling of actuators for flow control
  • Flow Sensing:  Flow sensors and controls to enable autonomous systems

Current Projects

sample TS cancellation

A turbulent boundary layer greatly increases the drag on a wing, and therefore aircraft fuel consumption.  By delaying the transition of organized, laminar flow into disorganized, turbulent flow, billions a year can be saved in fuel costs.  One way that this transition can be delayed is by using a vibrating surface element to suppress the Tollmien-Schlichting (TS) waves responsible.

In high speed helicopters, the reverse flow region present in the retreating side of the rotor disc can cause adverse effects on helicopter blades. During forward flight, the reverse flow region can form in the inboard section of the retreating blades due to the forward airspeed of the helicopter overcoming the local flow over the blades.

Sample OFV results over a NACA0015 airfoil using static tips

Drones and High Altitude Long Endurance vehicles typically operate at moderate to high Reynolds numbers based on airfoil chord length, i.e., Rec ≈ 105 to 106.  These vehicles are becoming increasingly important to applications like national security-related surveillance, search and rescue in dangerous terrain, scientific research, and animal conservation, among others. As such, the understanding flow conditions in such a way to ensure the safety of these aircraft is of paramount importance.

Separation is an adverse aerodynamic effect resulting in loss of aerodynamic performance. Previous studies on separation have mainly dealt with a two-dimensional analysis due to the assumption that the third dimension was negligible or that it was too complicated to analyze, leading to an incomplete analysis on separation. However, literature has indicated that this is insufficient in understanding separation and needs to be studied as such.

Previously tested 1/19th scale vertical tail model based on Boeing 767 tail with synthetic jet actuators

The addition of active flow control devices, such as synthetic jet actuators, on three-dimensional aerodynamic surfaces (i.e. vertical tail, wings, etc.) can lead to significant flowfield modification for beneficial improvements in aerodyanmic performance.  Previous work by Dr. Nicholas Rathay and collaborators on this project focused on augmenting the side force generated by synthetic jets through separation control on scaled vertical tail models.  Since commercial airplane tails are sized based on a single engine failure situation, they are larger than necessary for normal flight.

This project is acutely focused on the fundamental fluid physics governing the unsteady loads experienced by non-streamlined objects. Bluff bodies, as they are commonly known, experience abrupt separation of the flow which subjects them to the consequences of flows which may be unsteady and in many cases, transitioning from laminar towards turbulence. Examples of bluff bodies include tall buildings, bridge decks, and slung-load containers. One archetype geometry which has proven itself to be a benchmark for other studies is the rectangular prism.

As wind turbines increase in size in order to capture more power, so do much of the adverse natural effects such as wind gusts and atmospheric turbulence. Specifically, one of the largest factors in wind turbine fatigue has been shown to be dynamic stall, a phenomena where the angle of attack seen by the turbine blade passes in and out of its stall angle, resulting in highly fluctuating blade loading. Our goal is to mitigate these loads by using active flow control to make wind turbines last longer.

Sketch of SIA concepts (a) single-disk configuration (b) dual-disk configuration

Synthetic jet actuators (SJA) are zero net mass flux (ZNMF) devices traditionally constructed by forming a cylindrical cavity with an orifice in either its side or one of its bases (See Figure 1).  Piezoelectric disks are used as either one (a) or both (b) of the bases.  The disks are then vibrated by means of AC voltages.  As the disks move inward and outward, the volume of the cavity changes and air is rapidly ingested and ejected through the orifice.