The proposed SBIR program by Virtual AeroSurface Technologies (VAST) focuses on the development of a novel variant of pulsed blowing active flow control in which chemically-based flow control actuators are utilized to create high-impulse pulsed jets from discrete reaction chambers with a flowable propellant mixture provided to each. Chemically-based actuation is capable of producing high-impulse jets with sufficient control authority for full-scale flight vehicles and speeds, and, compared to other pulsed blowing flow control schemes, this type of actuation inherently requires less energy from other flight systems as the energy used to create the high jet momentum is stored chemically within the propellant. This general actuation approach has been successfully demonstrated before in the form of COMPACT (in which gaseous fuel and air are repetitively combusted to form pulsed jets for control of separation) and gas generator actuators (in which microfabricated combustion chambers with solid propellant mixtures are utilized for single-shot trajectory control of spin-stabilized projectiles). The innovation proposed here (in which flowable propellant is dynamically supplied to the chambers from an integrated local reservoir) will eliminate the challenges and infrastructure associated with supplying large volumes of air which are necessary for most pulsed blowing approaches and, to a lesser extent, for COMPACT. The proposed Phase I program will investigate multiple propellant chemical compositions, mechanisms for delivering the fuel and oxidizer compounds to the actuator chamber, and methodology for successful repetitive initiation of the chemical reaction within the chamber. A benchtop prototype with repetitive firing will be demonstrated at the end of the Phase I program. A prospective Phase II follow-on program will proceed to develop and demonstrate large arrays of these actuators and perform wind tunnel demonstrations of their utility for active flow control.
Potential NASA Commercial Applications: (Limit 1500 characters, approximately 150 words) Active flow control can have a wide range of applications for modifying and improving aerodynamic properties on fixed and rotary wing flight platforms. Successful implementations can yield reductions in the size of physical control surfaces on fixed wing aircraft with resultant improvements in weight and drag, and subsequently reduced fuel consumption. Similar improvements in fuel economy may also be envisioned with separation control and drag reduction applied to the fuselage or external stores of rotorcraft. Active flow control can also enable improved performance at off-design conditions with subsequent extensions of the flight envelope (e.g., short takeoff and landing for fixed wing aircraft and suppression of retreating blade stall for rotorcraft). Actuators with high control authority and minimized infrastructure and energy requirements will be vital to practical implementation of all of these applications and may enable shock manipulation control strategies at even higher flight speeds.
Potential NON-NASA Commercial Applications: (Limit 1500 characters, approximately 150 words) The benefits of aerodynamic flow control as described above for NASA applications will extend broadly to the commercial and military aerospace industry. In addition to external flow control applications for increased lift and reduced drag (with subsequently improved fuel economy and potential extensions of the flight envelope), active control of separation for internal flows is also of interest, including at serpentine engine inlets and even within gas turbines.
Technology Taxonomy Mapping: (NASA's technology taxonomy has been developed by the SBIR-STTR program to disseminate awareness of proposed and awarded R/R&D in the agency. It is a listing of over 100 technologies, sorted into broad categories, of interest to NASA.) Aerodynamics
