AME Seminar Series: Israel Wygnanski
Thursday, March 21, 2024 - 4:00 p.m.
Israel Wygnanski
Professor
Aerospace and Mechanical Engineering
University of Arizona
"On the Need to Reassess the Design Tools for Active Flow Control or Back to Square One on Active Flow Control by Blowing"
AME Lecture Hall, Room S212 | Zoom Link
Abstract: The pressure distribution on a surface, over which a wall-jet is blowing, is altered by the wall jet’s entrainment. It renders the boundary layer approximation – that justifies the use of an inviscid flow solution to determine the pressure over the surface – invalid. Thus, for Active Flow Control (AFC) by blowing to become a viable technology, some of the preconceptions associated with Boundary Layer Control (BLC) must be discarded. In particular, the momentum coefficient used to characterize BLC should be replaced by another variable that represents a conserved quantity that is independent of specific installations. Injected momentum is a vector quantity whose effect on a surface like a wing depends on its specific design, location, and orientation. Therefore, a new approach is proposed based on the AFC system’s power consumption and its mass flowrate. Moreover, all flow installations suffer from unavoidable losses, which must be determined in an unambiguous manner, allowing for an impartial comparison of AFC systems. Examples are provided from tests carried out at various universities and at NASA, exposing some popular misconceptions. Unfortunately, a design tool cannot be provided at this stage due to the complexity of the needed approach, but a method to assess the efficacy and efficiency of an evolving platform that includes AFC is suggested.
Bio: Israel J. Wygnanski, PhD, is professor of aerospace rngineering at the University of Arizona and professor emeritus at Tel Aviv University, in Tel Aviv Israel. In 2022, he was awarded the College of Engineering Extraordinary Faculty Award and ranked among top 250 scientists in aerospace and mechanical engineering worldwide. He is a Fellow, AIAA, APS and member of the National Academy of Engineering (NAE) with 300+ Scholarly publications (368 according to Google Scholar), 5 U.S. patents (all related to Active Flow Control). According to “Google Scholar” these publications were cited more than 17,000 times. Supervised more than 50 post-graduate students, some of them became distinguished professors in the US, in Germany and in Israel, while some others obtained leadership positions in industry (Israel Aerospace Industry, Airbus, Boeing, Raytheon, BMW etc.). He served as a PI on two major programs that originated at the university and ended in successful flight tests on manned airplanes. The first was sponsored by DARPA, leading to the flight test of the XV-15 tiltrotor airplane and the other was sponsored jointly by NASA & Boeing and was demonstrated on the Boeing 757 airplane after being tested at the AMES 40x80 wind tunnel.