Direct Numerical Simulation of Turbulent Flow Separation from a Wall-Mounted Hump

Postl, Dieter; Fasel, Hermann F.

doi:10.2514/1.14258

Cited by 40 publications

(17 citation statements)

References 14 publications

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“…Postl et al [35] showed good agreement in general, with minor discrepancies at few locations. Table 3-2 Summary of previous work performed using other turbulence models Saric et al [8,36] assessed a number of computational models viz.…”

Section: Direct Numerical Simulation (Dns)mentioning

confidence: 81%

Wall Modeled Large Eddy Simulation of Flow Over a Wall-Mounted Hump

Dilip

Tafti

2014

Volume 1A, Symposia: Advances in Fluids Engineering Education; Turbomachinery Flow Predictions and Optimization; Applications I

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Section: Direct Numerical Simulation (Dns)mentioning

confidence: 81%

Wall Modeled Large Eddy Simulation of Flow Over a Wall-Mounted Hump

Dilip

Tafti

2014

Volume 1A, Symposia: Advances in Fluids Engineering Education; Turbomachinery Flow Predictions and Optimization; Applications I

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“…To date, there have been only a limited number of applications of DNS or coarse-grid DNS to AFC applications (e.g., Barwolff, Wengle and Geggle, 1996;Wengle et al,2001;Postl and Fasel, 2006;Kotapati, Mittal and Cattafesta, 2007). When performing flow control computations with DNS, most researchers simplify the problem in the spanwise direction by solving over a finite slice, with periodic boundary conditions.…”

Section: Cfd Methodologiesmentioning

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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“…For the second approach we chose a model geometry, a laminar boundary layer (with or without curvature) under LPT conditions. These simulations were carried out using a higher-order-accurate incompressible finite-difference code [11] . The simpler geometry allows us to resolve all relevant scales of motion, from the laminar to the turbulent flow regime, and thus enables us to extract the relevant physics associated with separation control using steady and pulsed VGJs.…”

Section: Methodsmentioning

confidence: 99%

Active Flow Control of Low-Pressure Turbine Separation

Balzer

Groß

Fasel

2007

2007 DoD High Performance Computing Modernization Program Users Group Conference

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Operating low-pressure turbines (LPT) at off-design conditions or considering more aggressive designs can lead to laminar separation on the suction side of the LPT blades resulting in significant turbine and overall engine performance losses. In these instances, performance improvements may be achieved with active flow control (AFC). In an extensive experimental research program at the Air Force Research Laboratory (AFRL) at WrightPatterson AFB, Dr. R.B. Rivir and co-workers systematically investigated the benefits of AFC with steady and pulsed vortex generator jets (VGJs) for a linear PakB LPT cascade. Pulsed VGJs were found to be very effective in mitigating separation. We are employing two in-house computational fluid dynamics (CFD) research codes for investigating the physical mechanisms associated with AFC for LPT geometries. For simulations of the entire LPT blade, a high-orderaccurate finite volume code based on the compressible Navier-Stokes equations is used. Data from direct numerical simulations (DNS) with up to 19.4 million grid points of a PakB blade at Re=25,000 are compared with experimental data. For our fully resolved DNS that focus exclusively on the separated flow region, we are employing a high-order-accurate compact finite difference code based on the incompressible NavierStokes equations in vorticity-velocity formulation. Here, we study a separation bubble on a flat plate and on a curved wall model-geometry under LPT conditions. These simulations enable us to identify the intricate physical mechanisms associated with unsteady separation, transition, flow instabilities, and active control using VGJs. In particular, our simulation results provide an explanation for the stunning effectiveness of pulsed VGJs for separation control.

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Direct Numerical Simulation of Turbulent Flow Separation from a Wall-Mounted Hump

Cited by 40 publications

References 14 publications

Wall Modeled Large Eddy Simulation of Flow Over a Wall-Mounted Hump

Wall Modeled Large Eddy Simulation of Flow Over a Wall-Mounted Hump

Aerodynamic Flow Control

Active Flow Control of Low-Pressure Turbine Separation

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