Design and Validation of a New Experimental Setup for Dynamic Stall and Preliminary ControlResults

Design and Validation of a New Experimental Setup for Dynamic Stall and Preliminary ControlResults

Bibliographic Details
Main Author: Whiting, Nicole Lynn
Language:English
Published: The Ohio State University / OhioLINK 2019
Subjects:
Aerospace Engineering
Online Access:http://rave.ohiolink.edu/etdc/view?acc_num=osu1565823943355036
id ndltd-OhioLink-oai-etd.ohiolink.edu-osu1565823943355036
record_format oai_dc
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language English
sources NDLTD
topic Aerospace Engineering
spellingShingle Aerospace Engineering
Whiting, Nicole Lynn
Design and Validation of a New Experimental Setup for Dynamic Stall and Preliminary ControlResults
author Whiting, Nicole Lynn
author_facet Whiting, Nicole Lynn
author_sort Whiting, Nicole Lynn
title Design and Validation of a New Experimental Setup for Dynamic Stall and Preliminary ControlResults
title_short Design and Validation of a New Experimental Setup for Dynamic Stall and Preliminary ControlResults
title_full Design and Validation of a New Experimental Setup for Dynamic Stall and Preliminary ControlResults
title_fullStr Design and Validation of a New Experimental Setup for Dynamic Stall and Preliminary ControlResults
title_full_unstemmed Design and Validation of a New Experimental Setup for Dynamic Stall and Preliminary ControlResults
title_sort design and validation of a new experimental setup for dynamic stall and preliminary controlresults
publisher The Ohio State University / OhioLINK
publishDate 2019
url http://rave.ohiolink.edu/etdc/view?acc_num=osu1565823943355036
work_keys_str_mv AT whitingnicolelynn designandvalidationofanewexperimentalsetupfordynamicstallandpreliminarycontrolresults
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spelling ndltd-OhioLink-oai-etd.ohiolink.edu-osu15658239433550362021-08-03T07:12:25Z Design and Validation of a New Experimental Setup for Dynamic Stall and Preliminary ControlResults Whiting, Nicole Lynn Aerospace Engineering Dynamic stall is a time-dependent flow separation and stall phenomenon that can occur in any application where the lifting surface or airfoil is subjected to an unsteady motion. The main adverse characteristics associated with dynamic stall include the production of high torsional and vibratory loads on the lifting surface. In rotorcraft, this combination of blade torsion and vibration significantly reduces the life of the blade and can lead to rotor component fatigue and eventually structural failure. Therefore, conditions capable of generating aerodynamic flutter are avoided, limiting the flight envelope of rotorcraft, specifically the forward flight speed. For this reason, understanding and controlling dynamic stall is of great interest to the rotorcraft community.Nanosecond dielectric barrier discharge (NS-DBD) plasma actuators are minimally complex, require relatively low power, and can maintain control efficacy in high speed flows making them an ideal flow control technique. In a NS-DBD plasma actuator, a high-voltage nanosecond pulse produces rapid, localized heating that results in a thermal perturbation. The thermal perturbations over a certain frequency range, when introduced in a region of receptivity of the shear layer over the separated region on an airfoil, can excite natural instabilities in the shear layer and generate coherent flow structures. These structures can entrain high-momentum free stream air into the low-momentum region near the airfoil surface, energizing the flow and mitigating or eliminating separation. Previous work in The Ohio State University’s Gas Dynamics and Turbulence Laboratory included the development of an experimental setup for preliminary investigation of dynamic-stall control using NS-DBD plasma actuators. The results showed promise at suppressing the DSV and reattaching the flow over a NACA 0015 airfoil, significantly reducing unsteady loads. However, there were some shortcomings related to the experimental setup that generated significant uncertainties in the experimental results. This work improves upon the previous effort by redesigning the experimental setup and control system to diminish the uncertainty in the data. After the upgraded experimental setup was constructed, baseline static and dynamic data for a clean NACA 0012 airfoil was collected and compared to results and trends seen in literature to validate the new system. Overall, the aerodynamic coefficients matched the trends seen in literature, thereby validating the experimental setup hardware and software.A NACA 0012 airfoil with a plasma actuator located at the leading edge was then tested at Re=300,000, for three motion reduced frequencies k = [0.05, 0.075, 0.10], two motion profiles: ∝(t)=10+6 sin(ωt) (light dynamic stall) and ∝(t)=10+10 sin(ωt) (deep dynamic stall), and excitation frequencies ranging from 0 to 2,000 Hz (St<sub>e</sub>=0 to St<sub>e</sub>≈13.40). The overall excitation trends were similar for all combinations of motion reduced frequency and motion profile. All excited cases exhibited reduced lift and drag leading to a significant overall increase in the lift to drag ratio. This is attributed to a reduction in accumulated vorticity at the leading edge and thereby a reduction in the DSV strength. The maximum lift to drag ratio increase at k=0.075 was 85.1% and 15.1% for light dynamic stall and deep dynamic stall, respectively. As the motion reduced frequency increased a higher peak lift to drag ratio was observed in control cases. This suggests that control effectiveness will increase as the motion reduced frequency is increased towards values used in application.It was also observed that all excited cases exhibited earlier flow reattachment and a reduction in lift hysteresis. This is significant as reattachment significantly reduces unsteady loads and decreases drag while a reduction in lift hysteresis is associated with a reduction in vibratory loads. \ Lastly, when a sufficiently high excitation frequency (St<sub>e</sub> > 0.3) is used, all cases exhibit a reduction in the negative aerodynamic damping coefficient leading to an increased total aerodynamic damping coefficient and significantly reducing the chance of aerodynamic flutter.Future work will include the use of PIV to better understand the flow physics. The ability to see the DSV and the excitation structures at excitation frequencies of interest could potentially provide significant information and understanding of the flow with which to optimize control. 2019 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1565823943355036 http://rave.ohiolink.edu/etdc/view?acc_num=osu1565823943355036 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

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