Synergy Aircraft 'Powered' Drag Reduction скачать в хорошем качестве

Synergy Aircraft 'Powered' Drag Reduction

Synergy designer John McGinnis discusses 'natural laminar flow' and 'powered drag reduction' at AirVenture Oshkosh 2012. Most aircraft fuselages provide little laminar flow, due to their shape and irregular surfaces. Achieving 'natural laminar flow' over a high percentage of a fuselage would cut their drag in half (!) Moving another step beyond this important (but rare) result for powered aircraft requires using power differently. Powered drag reduction can cut the drag, even of natural laminar flow, in half yet again... even more at higher Reynolds numbers. When power from an energy source is used to reduce drag, rather than simply to make thrust, the traditional drag and lift equations no longer provide accurate results. Mathematical consideration of the total energy balance in aircraft flight requires a step into the field known as "open thermodynamics". In such applications where the energy is applied for drag reduction, simple equations using the term called 'dynamic pressure' have to be balanced by every influence of outside energy on the behavior of the system. Most preliminary calculation does not do this, leading to overly pessimistic performance estimation and a lack of large scale experimentation. Recent work by Mark Drela, PhD at MIT avoids the kinetic energy controversy by providing a power balance framework from which to accurately explore the entropy and enthalpy of the system as a whole. https://info.aiaa.org/tac/ASG/APATC/S... In this talk, (recorded Wednesday July 25, 2012) McGinnis explores several of the basic ways to use open-thermodynamic principles for drag reduction, such as wake propulsion, boundary layer control, and pressure thrust.