Computational Analysis Of A Two Slot Circulation Control Airfoil

Computational Analysis of a Two-slot Circulation Control Airfoil

Computational Analysis of a Two-Slot Circulation Control Airfoil

A two-slot circulation control airfoil was analyzed using the two-dimensional, compressible, mass-averaged, Navier-Stokes equations. The implicit Beam-Warming approximate factorization technique was used to calculate airfoil characteristics for a flight Mach number of 0.3 and a reynolds number near 3 million. The results were then compared to a previous one-slot solution. An existing circulation control airfoil was modified to include a second slot. Different blowing rates were then applied to each slot in various combinations. The lift generated for a given total blowing momentum for the two-slot airfoil was nearly identical to that for a single-slot airfoil when the lowest blowing rate was applied to the first slot. Although the lift per unit blowing momentum did not increase over the single-slot case, the maximum lift coefficient was increased due to the increased momentum available from the additional slot. Separation angle increased when a small amount of blowing was applied to the first slot, and additional blowing applied to the second slot. The airfoil moment followed the same trend as the single slot, and was less dependent on which the flow was applied. Due to the lack if experimental data, and the difficulty in modeling drag for the circulation control airfoil, it is difficult to compare drag. Keywords: Theses. (KR).

Foundations of Circulation Control Based Small-Scale Unmanned Aircraft

This book focuses on using and implementing Circulation Control (CC) - an active flow control method used to produce increased lift over the traditionally used systems, like flaps, slats, etc. - to design a new type of fixed-wing unmanned aircraft that are endowed with improved aerodynamic efficiency, enhanced endurance, increased useful payload (fuel capacity, battery cells, on-board sensors) during cruise flight, delayed stall, and reduced runway during takeoff and landing. It presents the foundations of a step-by-step comprehensive methodology from design to implementation and experimental testing of Coandǎ based Circulation Control Wings (CCWs) and CC system, both integral components of the new type of aircraft, called Unmanned Circulation Control Air Vehicle. The methodology is composed of seven coupled phases: theoretical and mathematical analysis, design, simulation, 3-D printing/prototyping, wind tunnel testing, wing implementation and integration, and flight testing. The theoretical analysis focuses on understanding the physics of the flow and on defining the design parameters of the geometry restrictions of the wing and the plenum. The design phase centers on: designs of Coandǎ surfaces based on wing geometry specifications; designing and modifying airfoils from well-known ones (NACA series, Clark-Y, etc.); plenum designs for flow uniformity; dual radius flap designs to delay flow separation and reduce cruise drag. The simulation phase focuses on Computational Fluid Dynamics (CFD) analysis and simulations, and on calculating lift and drag coefficients of the designed CCWs in a simulation environment. 3-D printing and prototyping focuses on the actual construction of the CCWs. Wind tunnel testing centers on experimental studies in a laboratory environment. One step before flight testing is implementation of the qualified CCW and integration on the UAV platform, along with the CC system. Flight testing is the final phase, where design validation is performed. This book is the first of its kind, and it is suitable for students and researchers interested in the design and development of CCWs for small-scale aircraft. Background knowledge on fundamental Aerodynamics is required.