Experiments in Fluids

Abstract During wind turbine installation or idling, the blades often operate at large angles of attack, where vortex-induced vibration (VIV) can occur. This study experimentally investigates the aerodynamic characteristics of a plunging NACA0021 airfoil at a fixed angle of attack of $$90^\circ $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mn>90</mml:mn> <mml:mo>∘</…

Abstract Unstart dynamics are experimentally investigated in a streamtraced hypersonic inlet at angles of attack, $$\alpha = -5^\circ $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>α</mml:mi> <mml:mo>=</mml:mo> <mml:mo>-</mml:mo> <mml:msup> <mml:mn>5</mml:mn> <mml:mo>∘</mml:mo> </mml:msup> </mml:mrow> </mml:math> , $$\alpha = 0^\circ $$ <mml:math xmlns:mml="http:/…

Abstract Multi-exposure (ME) 3D particle tracking velocimetry (3D-PTV) is a specific recording variant whereby more than two samples of the particle position are obtained to overcome some limitations of single-exposure double-frame recordings, such as accelerometry, pressure from PIV, or to further extend the dynamic velocity range. Compared to time-resolved (TR) systems, ME lowers system require…

Abstract This paper investigates the effects of the interaction between an under-expanded supersonic jet and a flat plate on screech generation. The plate is installed parallel to the jet axis and an experimental investigation is made for several configurations corresponding to different radial distances of the plate, H , from the nozzle axis. Acoustic measurements are carried out to evaluate the…

This paper presents a novel adaptive control pattern (ACP) for real-time feedback control of flow separation over airfoils using sparse processing particle image velocimetry (SPPIV) and dielectric barrier discharge plasma actuators. The study addresses the challenge of suppressing separation in deep stall at low Reynolds numbers, where previous feedback-based methods often fail to maintain effect…

Abstract Contaminants such as microplastics, ash, and pollen are constantly carried between the ocean and atmosphere via raindrops, splash droplets, and breaking waves. These contaminants have an impact on marine life via bioaccumulation and alter the chemistry of the ocean, consequently impacting our weather prediction and radar systems. However, there are few studies involving deep pool drop im…

A high-frequency dynamic calibration system for pressure-sensitive paint (PSP) was developed using cavity-induced jets. The dominant frequency for dynamic calibration was adjusted to the range of 9–16 kHz by scaling the cavity. The dominant flapping frequencies corresponding to different cavity lengths were identified. The distributions of pressure fluctuations across cavities were measured using…

Abstract The influence of turbulence on the aerodynamics of a NACA0012 wing and the behavior of the associated wingtip vortex is investigated at a chord-based Reynolds number of 5000. The study is conducted through water tunnel experiments using a half-wing setup with an aspect ratio of 6 and an angle of attack of 10 degrees. At this low Reynolds number, relevant for aerodynamics at low-speed, th…

Abstract The catastrophic failure of the Ariane 5 ECA heavy launcher in December 2002 underscored significant gaps in understanding the dynamic loads acting on the vehicle’s base region. Investigations revealed that aerodynamic interactions between the nozzle exhaust plume and the launcher wake, particularly the phenomenon of “buffeting,” led to intense oscillatory mechanical loads. This study ad…

Abstract Dispersed two-phase flows at air–water interfaces are ubiquitous in environmentally relevant flows such as in the dispersion of floating microplastics or transport processes across the air–sea interface. In the current study, we propose a method to study such flows through the study of a relatively flat turbulent free surface laden with spherical floating particles (“floaters”). The free…