Novel Approach for Endurance Testing of Riblet-Structured Thin Sheets Under Realistic Loading Conditions in Active Drag-Reduction Systems

Stille, S.; Schiek, M.; Silex, W.; Beck, Tilmann; Waasen, Stefan van; Singheiser, L.

doi:10.1520/jte20150369

Cited by 2 publications

(2 citation statements)

References 21 publications

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“…Despite the low skin friction reductions at higher Reynolds numbers, a near 10% reduction for a specific case is significant. As a step towards implementing this system in an application, Stille [89] conducted an endurance test of the combined EM actuator system and riblets. This was done in order to determine the fatigue life and failure method of the aluminum plate and riblets.…”

Section: Spanwise Traveling Waves With Wall-normal Motionmentioning

confidence: 99%

Turbulent Boundary Layer over a Piezoelectrically Excited Traveling Wave Surface

Musgrave

Tarazaga

2019

AIAA Scitech 2019 Forum

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Skin friction drag plays a significant role in determining the fuel efficiency of a vehicle. Reducing the skin friction thus has implications in a number of applications such as aircraft, ships, and automobiles. In recent years, a large amount of studies have researched various active drag reduction methods. One particular method involves active wall motion with the use of spanwise traveling waves. These out-of-plane traveling waves interact with the vortices in the turbulent boundary layer and weaken the bursting events that are responsible for increased skin friction drag. Computational and experimental studies have shown that these spanwise traveling waves are able to reduce the skin friction by upwards of 13% in turbulent flow. However, previous studies generated traveling waves using bulky actuation setups requiring arrays of discrete actuators that limited the achievable bandwidth and traveling wave patterns. In order for traveling waves to be a practical drag reduction method, a more implementable wave generation method is necessary. A promising traveling wave generation method is known as two-mode excitation. This technique takes advantages of a surface's inherent structural properties to generate steady-state traveling waves in an open-loop fashion. In addition, the waves can be excited at most frequencies and using a small number of low-profile piezoelectric actuators. Previous research into two-mode excitation has primarily focused on one-dimensional beams. Traveling waves have been generated on a two-dimensional surface, but this was done from a fundamental standpoint with the resultant waves propagating in arbitrary directions. Before the two-mode excitation method can be applied for drag reduction, traveling waves must be generated on two-dimensional surfaces with tailorable propagation patterns. The goal of this research is the development and testing of an implementable traveling wave generation method that alters the turbulent boundary layer with the aim of reducing skin friction drag. The first objective is to further develop the two-mode excitation method in order to tailor the traveling waves generated on a two-dimensional plate. Then, these tailored traveling waves are experimentally tested to determine their effect on the turbulent boundary layer. By directly investigating the boundary layer, a more fundamental approach is taken than only focusing on the skin friction drag. Finally, the overall effect of the traveling waves on the boundary layer are compared with standing waves. vii None of this would have been possible without the support of my family. My parents, Robert and Jacqueline, you raised me to be the person I am today. You have always been there with support and encouragement, and I am eternally grateful. I want to thank my brothers, Brian and Robert, and their wives, Katie and Lindsay. You are always there to chat and you provided many late nights of fun. Finally, I want to thank Alexis Gushiken and the endless support she has given. You always know when to motivate, encourage, o...

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Section: Spanwise Traveling Waves With Wall-normal Motionmentioning

confidence: 99%

Turbulent Boundary Layer over a Piezoelectrically Excited Traveling Wave Surface

Musgrave

Tarazaga

2019

AIAA Scitech 2019 Forum

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“…Within this group we are developing an improved Lorentz force based actuator system for further experiments in turbulence control exploring beyond previous experimental results [1]. With a very similar approach, also very high cycle fatigue (VHCF) experiments requiring constant monitoring of the actuator movements have been successfully carried out [2]. More recent results include the development of a smooth transition system for sine signals used for this actuator system on the basis of direct digital synthesis (DDS) [7].…”

Section: Introductionmentioning

confidence: 99%

Sensors for waveform control in a Lorentz force based actuator system for turbulence research

et al. 2017

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Abstract-This work discusses the use of analog light barrier and Hall sensors for waveform control in an actuator system for turbulence research. The system shall produce up to 80 Hz, 80 mm wavelength running surface wave with amplitudes from 50 to 1000 µm. To ensure both, waveform and amplitude, the control algorithm requires real time amplitude measurements of all 20 actuators. Techniques are described to extend the limited measurement range of analog light barriers and to reduce impact of mechanical disturbances on the measurement process by placement and compensation. Also a small bar permanent magnet together with Hall sensors to track position are employed and a method for reducing impact of the strong magnetic stray fields affecting Hall sensors in this actuator system is developed.

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Novel Approach for Endurance Testing of Riblet-Structured Thin Sheets Under Realistic Loading Conditions in Active Drag-Reduction Systems

Cited by 2 publications

References 21 publications

Turbulent Boundary Layer over a Piezoelectrically Excited Traveling Wave Surface

Turbulent Boundary Layer over a Piezoelectrically Excited Traveling Wave Surface

Sensors for waveform control in a Lorentz force based actuator system for turbulence research

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