Date of Award
2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Mechanical and Aerospace Engineering
Committee Chair
Chang-kwon Kang
Committee Member
Haiyang Hu
Committee Member
Kunning G. Xu
Committee Member
Farbod Fahimi
Research Advisor
Konstantinos Kanistras
Subject(s)
Airplanes--Wings--Aerodynamics, Trailing edges (Aerodynamics), Airplanes--Control surfaces
Abstract
Active Flow Control (AFC) techniques are a class of methods that improve aerodynamic efficiency by affecting the flow field through actuation or interaction to produce a desired change in flow behavior. Circulation control (CC), which is considered one of the most effective AFC methods, holds significant potential to enhance aircraft efficiency and has been researched for lift enhancement and boundary layer control, among other applications. However, its practical application has been constrained by high mass flow requirements and several unanswered questions in current research. A critical area of investigation is the interaction between trailing-edge blowing and 3D unsteady effects under complex flow conditions, such as leading-edge vortices, tip vortices, or crossflow instabilities, which can affect performance and cause flight instability, especially in small-scale unmanned aerial vehicles (UAVs) with low aspect ratio wings. Understanding the complex flow phenomena associated with unsteady flap motion combined with CC is essential for the design and optimization of efficient AFC systems. This research experimentally investigates these complex flow structures and addresses the gaps in applying CC for lift enhancement in small-scale UAVs. It also investigates spanwise segmented blowing in an attempt to reduce mass flow requirements. Two low aspect ratio wing configurations are designed and developed for wind tunnel testing: one with a single plenum chamber and a second with multiple plenum chambers. Both wings feature a modified NACA0012 profile, and direct-force and particle image velocimetry (PIV) measurements are performed at a free stream Reynolds number of 1.05 x 10^5 based on the airfoil chord. 2D and stereoscopic phase-locked PIV measurements are collected at three spanwise locations for both steady and actuating flap conditions at various actuation speeds and blowing intensities. Proper orthogonal decomposition and modified Q-criterion methods are employed to analyze the PIV data. The wake dynamics revealed that flap actuation strengthens the tip vortex in the absence of active blowing. However, the combination of flap actuation and continuous active blowing proved more effective in controlling the boundary layer compared to a stationary flap at the same blowing intensities. Force measurements demonstrate that a 33.33% reduction in mass flow is achieved by employing spanwise segmented blowing while maintaining the same lift coefficients.
Recommended Citation
Vechalapu, Tulasi Ram, "Experimental investigation of steady and unsteady effects of a circulation control wing with spanwise segmented blowing" (2024). Dissertations. 422.
https://louis.uah.edu/uah-dissertations/422