Synchronous Spatiotemporal Scanning of Compliant Surfaces Under Unsteady Aerodynamic Loading
Abstract
This proposal focuses on the development of a non-invasive high-resolutionspatiotemporal surface deflection measurement up to O(25Mhz), which meets the needs of mostapplications where the interaction between flow field and time-dependent structure deformation isimportant. The proposed system will be based on the Scanning Laser Doppler Vibrometer that willbe integrated into Short Takeoff and Vertical Landing (STOVL) facility at Florida Center forAdvanced Aero Propulsion (FCAAP) as well as the subsonic, supersonic, anechoic and polysonicwind tunnels (up to Ma 5) at the FAMU-FSU College of Engineering, thus enabling much-neededinsight into the flow-structure interaction phenomena of interest to DOD over a broad range ofapplications. There is a critical need for understanding the interaction between a solid and the fluidwhen strong unsteady flow-induced forces act on the surface such as those for STOVL aircraftduring hover and near deck operation. Here structural vibration can be a critical issue due to itsrole in high-amplitude discrete tones and associated adverse ground effect. The inclusion of flowresponsive surfaces induces structural waves and vibration-induced non-local modifications of theflow field that often results in a knowledge-gap between the measured flow quantities andobservations in the real system. To achieve a more comprehensive understanding of this coupledproblem, time-resolved measurements of the surface deformation that are synchronous with fluidmeasurements are necessary. Traditional techniques for surface deformation measurements utilizeeither patterned surfaces or embedded arrays of piezoelectric accelerometers- each approach hasmajor shortcomings. The present method uses non-invasive scanning vibrometers to measuresurface motion, which is routinely utilized in vibration and wave propagation studies. Suchanalyses have not been conducted for hovering STOVL aircraft with single/dual impinging jetswhere one can obtain spatiotemporal maps of the surface motion while developing correlation ofthe surface response with aeroacoustic properties over the entire model. This is also lacking inother DOD problems where FSI is critical a number of these will also be examined in our lab.The ability to measure structural motion in complex and unsteady flow conditions withoutrequiring an enormous distribution of discrete sensors and model preparation will have asubstantial impact on diverse fields that will benefit from high-resolution distributed surfacemeasurements. It will allow identification of the fundamental physics of FSI problems, real-timemonitoring and damage identification under unsteady turbulence-induced forces leading toeffective control techniques of flying and hovering aircraft. Primary objective of proposedinstrumentation is to accelerate the use of a Polytec Scanning Vibrometer (PSV) within the FCAAPSTOVL facility and the Polysonic Wind Tunnel (M = 0.2 to 5) and other subsonic wind tunnels tomeasure unsteady surface deformation at realistic flow conditions concurrently withcomprehensive flow measurements. PSV will also greatly enhance the ability to mentor graduateand undergraduate students working on interdisciplinary fluid-structure interaction problems indiverse teams at the FAMU-FSU College of Engineering. The device can measure surfacevelocities up to 30m/s, well within the range for our intended applications with less than O(10KHz)and O(1mm) deflection. It has a dynamic range of up to 25MHz to measure wave propagation ofthe structure and identify natural modes of the supporting structure.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 06, 2021
- Source ID
- N000142112292
Entities
People
- Farrukh S. Alvi
Organizations
- Florida State University
- Office of Naval Research
- United States Navy