Boundary layer control by unsteady vortex generation

Viets, Hermann; Piatt, Michael; Ball, M.

doi:10.1016/0167-6105(81)90035-0

Cited by 15 publications

(4 citation statements)

References 1 publication

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“…3 Fluidic actuators use fluid injection or suction, including synthetic jet, 4,5 pulsed jet, 6 pulsed suction, 7 and fluidic oscillators. 8 Moving surface actuators mainly include wall oscillation, 9 oscillating wire, 10 rotating surfaces, 11 and traveling wave walls. 12 The last class, plasma actuators, includes single dielectric barrier discharge (SDBD) plasma, 13 localized-arc-filament plasma actuators (LAFPA), 14 and plasma synthetic jet actuators (PSJA).…”

Section: Introductionmentioning

confidence: 99%

Proof of concept study on a self-driven pulsed jet on a compressor stator blade by numerical simulation

Lu,

Deng,

Jiao

2023

Proceedings of the Institution of Mechanical Engineers, Part G:

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This study presents a new concept of self-driven pulsed jet flow control on a compressor stator blade. This passive unsteady flow control method has the advantage that neither external flow nor electrical source is needed. This study’s preliminary proof-of-concept study on a low-speed compressor stator blade is performed using numerical simulation. When the pulsed jet frequency is 100 Hz, the optimum control performance and control efficiency are reached, and the total pressure loss coefficient is reduced by 8.9%. As the valve’s rotational speed increases, the pulsed jet’s momentum coefficient decreases gradually. The analysis of the unsteady characteristics of the self-driven pulsed jet shows that the jet velocity is close to a periodic square wave signal, and the typical reduced jet velocity ranges from approximately 0.15 to 0.8. Moreover, the time-averaged driving torque on the valve depends on the rotational speed and is relevant to the self-starting and self-driven characteristics of this passive flow control method. Under different bearing resistance torque, the self-driven valve behaves differently in three cases that can self-start and be self-driven, cannot self-start but can be self-driven, and cannot self-start nor be self-driven.

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Section: Introductionmentioning

confidence: 99%

Proof of concept study on a self-driven pulsed jet on a compressor stator blade by numerical simulation

Lu,

Deng,

Jiao

2023

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…One method to suppress or control these hydrodynamic instabilities is to implement an active or passive control to modify the flow field: micro-jets, vibrating/moving parts, plasma or morphing actuators have been reported (Viets, Piatt & Ball 1981;Gelzer & Amitay 2002;Moreau 2007;Dong, Triantafyllou & Karniadakis 2008;Godoy-Diana et al 2009;Cattafesta & Sheplak 2011;Chinaud et al 2014). Controlling flows around objects has been extensively used in the aerodynamic community to reduce drag or to modify the global flow topology (Roshko 1993;Leweke, Provansal & Boyer 1993;Mittal & Balachandar 1995;Cimbala, Nagib & Roskho 1988;Prasad & Williamson 1997).…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical investigation of flames stabilised behind rotating cylinders: interaction of flames with a moving wall

et al. 2017

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Steady methane/air laminar premixed flames stabilised on a cylindrical bluff body subjected to a continuous rotation are analysed using joint direct numerical simulations (DNS) and experiments. DNS are carried out using a 19 species scheme for methane/air combustion and a lumped model to predict the cylinder temperature. Rotation of the cylinder induces a symmetry breaking of the flow, and leads to two distinct flame branches in the wake of the cylinder. DNS are validated against experiments in terms of flame topologies and velocity fields. DNS are then used to analyse flame structures and thermal effects. The location and structure of the two flames are differently modified by rotation and heat transfer: a superadiabatic flame branch stabilises close to the hot cylinder and burns preheated fresh gases while a subadiabatic branch is quenched over a large zone and anchors far downstream of the cylinder. Local flame structures are shown to be controlled to first order by the local enthalpy defect or excess due to heat transfer between the cylinder and the flow. An analysis of the local wall heat flux around the cylinder shows that, for low rotation speeds, the superadiabatic flame branch contributes to wall heat fluxes that considerably exceed typical values found for classical flame/wall interactions. However, for high rotation speeds, fluxes decrease because the cylinder is surrounded by a layer of burned gases that dilute incoming reactants and shield it from the flame.

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“…These are sometimes called micro-electro-mechanical systems (MEMS), but the most common length scales are O(10 −3 ) to O(10 −1 ) m. Two of the most common actuator types are fluidic actuators (e.g., ZMF, Nagib et al, 2006) that are deployed behind the slot to produce oscillatory perturbations, and surface-mounted mechanical oscillators (e.g., Viets, Piatt and Ball, 1987;Neuburger and Wygnanski, 1987;Bar-Sever, 1989). Recent decades have witnessed significant advances in zero and nonzero mass-flux devices including piezoelectric (Chen et al, 2000;Glezer and Amitay, 2002) valve-type (Seifert, Darabi and Wygnanski, 1996;Bachar, 2001;Seifert and Pack, 1999) and pulsed combustion or detonation-driven (Crittenden et al, 2001) devices.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic Flow Control

Greenblatt

Wygnanski

Rumsey

2010

Encyclopedia of Aerospace Engineering

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Active flow control (AFC) has re‐emerged as a formidable research area in aerodynamics; this chapter provides a broad overview of modern developments. The control of large coherent structures via periodic perturbations and the mechanical means to achieve this have been at the heart of these developments. AFC has been demonstrated in wind tunnels over a 4 order‐of‐magnitude Reynolds number range and at high subsonic Mach numbers. Recently, an active flow control system for tiltrotor download alleviation was successfully flight tested. Most of the AFC research has focused on airfoil configurations including so‐called simplified high‐lift systems, although drag reduction, three‐dimensional configurations and flows, are also actively researched. Experiments that elucidate new aspects or isolate controlling parameters are considered to be invaluable for advances in the foreseeable future. Concurrently, the development of effective, robust, and system‐efficient actuators and sensors will determine the scope of applications. Computational fluid dynamics (CFD), with various levels of turbulence model complexity, is the primary tool for prediction of these flows. Coordinated experiments designed specifically for CFD validation will be invaluable for developing these codes. Recent progress in the arena of simulation methods such as direct numerical simulation (DNS), large eddy simulation (LES), and hybrid Reynolds‐averaged Navier–Stokes (RANS)/LES is expected to continue. Nevertheless, due to the expense of these methods, effort should also be expended in improving RANS predictions.

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Boundary layer control by unsteady vortex generation

Cited by 15 publications

References 1 publication

Proof of concept study on a self-driven pulsed jet on a compressor stator blade by numerical simulation

Proof of concept study on a self-driven pulsed jet on a compressor stator blade by numerical simulation

Experimental and numerical investigation of flames stabilised behind rotating cylinders: interaction of flames with a moving wall

Aerodynamic Flow Control

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