Dragonflies and CoFlow Technology

Dean Sigler Biomimicry, Electric Powerplants, Sustainable Aviation Leave a Comment

A Different Approach to Regional Aerial Mobility

Dr. Gecheng Zha sees a relationship between dragonflies and his CoFlow technology.  Mimicking the look, and more importantly, the aerodynamics of the creature.  Director of the Aerodynamic and CFD Lab, University of Miami (UM), Zha is expanding his research into eVTOL (electric Vertical Take Off and Landing) aircraft, Martian exploration, and large scale sailing ships.

His talk at the 2019 Sustainable Aviation Symposium at UC Berkeley was a revelation and his subsequent work shows the multiple directions in which his CoFlow technology can be applied.

Urban and Regional Air Mobility

CoFlow Jet does the improbable trick of pushing air over the wing, only to have it sucked in near the trailing edge, passed through an internal compressor and blown out through slots in the wing’s leading edge, creating a steady stream that increases the lift coefficient and lowers the drag coefficient.  Zha claims that this enables the use of battery power because the propulsors can be smaller and draw less current.  This dragonfly-like configuration features prominently in MAGGIE, described below.

The craft can be flown in electric Conventional Take Off and Landing (eCTOL) or electric Vertical Take Off and Landing modes, although eVTOL requires over thee times the energy of eCTOL.  Zha’s CoFlow technology is not limited to dragonfly configurations, though, as shown in his design for a four-seat touring craft that resembles a high performance sailplane.  A canard configuration can be seen in the image topping this blog entry.

GreenCarCongress.com reported on the four-seater, noting its design work with NASA and what they termed “Deflected Slip Steam (DSS) technology.”

CoFlow four-seat craft would carry,  “4 passengers with a range of 360 miles and cruise speed of 221 Miles/h. It is based on current Li-Ion battery power density of 250Wh/kg. ”  Expect more with next generation batteries.

The publication described the workings for the system.  “DSS facilitates vertical takeoff and landing as well as hovering and cruising without tilt rotors, tilt wings or lift plus. CoFlow Jet’s CFJ technology is composed of an active-flow control airfoil with micro-compressors mounted inside the airfoil that vacuum air into the trailing edge and then inject it near the leading edge, tangential to the main air flow.

“CoFlow Jet’s CFJ technology was tested in a DARPA-funded wind tunnel experiment, and the company says a preliminary design of the overall vehicle is complete.

“’We are developing advanced fully electric vertical and short takeoff and landing (eV/STOL) vehicles using DSS enabled by CFJ, which will make urban transportation and eCommerce economically viable,’ said CoFlow Jet CEO and University of Miami Professor Dr. Gecheng Zha. ‘Tilt rotors, tilt wings and lift plus may soon be part of history. Such a vehicle could also be used on Mars, as it could generate a nearly 10 times higher cruise lift coefficient compared to existing fixed-wing aircraft, making it the most effective vehicle not only here on Earth but also on Mars where the air density is one-hundredth that of Earth.’”

A Mars Mission

It isn’t the Blue Danube Waltz from 2001, but Tchaikovsky’s Piano Concerto Number One  accompanies MAGGIE (Mars Aerial and Ground Global Intelligent Explorer) to Mars in an incredibly complex multi-stage mission.  Similarly exotic approaches have delivered long-lived ground-based rovers and a dauntless little helicopter to the Martian terrain.  In this case, MAGGIE has to contend with the thin Martian atmosphere, one or two percent of earth’s atmospheric “weight.”  Having a series of internal compressors “turbo-charging” that thin atmosphere will probably assist MAGGIE in its flights.

CoFlow technology is not limited to the terrestrial, but can be applied to maritime use, which could have more climate impact than that gained from aerial applications.

CoFlow Rotors Replace Bunker Oil

Cruise ships, cargo container vehicles, and large marine vessels all use prodigious amounts of energy, much of it heavily polluting the sea and sky.  Bunker oil, also known as Heavy Fuel Oil (HFO) powers much of the world’s shipping because of its low price.   Zha’s CoFlow cylinders would take the place of traditional sails to propel a ship along its course at even lower cost.

Zha is as enthusiastic for the seaborne cylinders as he is for CoFlow technology in urban or regional aerial transit.  “What’s old is new again,” he says.  “With the technological advancements of today, wind-assisted propulsion is an efficient alternative to diesel engines. And the major advantage is that it’s environmentally friendly – an effective way to decarbonize the shipping industry which is responsible for about 3% of global greenhouse gas emissions.”

Zha’s CoFlow approaches can be used even on wind turbines, further expanding the potential for generating energy for the grid.  We have covered only a small part of what CoFlow’s web sites include.  With the exciting potential inherent in Zha’s designs, not even the sky is the limit.

Leave a Reply

Your email address will not be published. Required fields are marked *