Effectiveness of vortex generator jets and wall suction on separated flows in serpentine-duct diffuser

Keerthi, M. C.; Kushari, Abhijit

doi:10.1016/j.ast.2014.01.013

Cited by 18 publications

(7 citation statements)

References 18 publications

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“…The second one is that the separation is interacting with the fan, which ingests the recirculation zone. Two conclusion can consequently be drawn: first, aspiration of the separated zone downstream of the shock can be a more efficient way of applying flow-control, 15 rather than upstream vortex generators or micro-jets, which are more adapted to leading-edge separations. 16 Second, the fan must be taken into the account for the evaluation of the flow-control effectiveness, since the reattachment points is determined by the interaction between the separation bubble and the fan blades in the lowest position.…”

Section: Results With Active Flow Controlmentioning

confidence: 99%

Numerical Simulations of Fan/Airframe Interaction with Active Flow-Control

Sartor¹,

Burlot²,

Méheut³

2018

2018 Applied Aerodynamics Conference

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This paper presents a numerical study of a Ultra High Bypass Ratio turbofan (UHBR) with and without active flow control in isolated conditions. Steady and unsteady Reynolds-Averaged Navier-Stokes equations are solved on a 360 • representation of the isolated engine, where the rotating fan and the outlet guide vane (OGV) are fully modelled to analyse the interaction with the airframe. Spatial and temporal resolution are discussed, and different approaches are proposed providing increasing levels of fidelity. The configuration is first investigated without control for various angles of attack at low-speed conditions. Then, the angle of attack is increased until massive flow detachment is observed, and active flow-control technique is proposed to mitigate the impact of the separated zone using flow-suction upstream of the fan. A parametric study is proposed using steadystate simulations, aiming at evaluating the most efficient configuration that allows a gain in the overall performance of the engine while limiting the costs induced by the control device. This work has been conducted in the framework of the European funded Clean Sky 2 project ASPIRE, aiming at demonstrating the ability of existing numerical and experimental methods to accurately assess the aerodynamic and acoustic performance of UHBR engines thanks to a reliable modelling of fan/airframe physical interactions.

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Section: Results With Active Flow Controlmentioning

confidence: 99%

Numerical Simulations of Fan/Airframe Interaction with Active Flow-Control

Sartor¹,

Burlot²,

Méheut³

2018

2018 Applied Aerodynamics Conference

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“…increase in stability margin is obtainable. Furthermore, some investigators use suction and blowing simultaneously [26,31,24] in order to prevent advantageous of both ow control methods. This simultaneous action generally supplied by high pressure jets which are basicly driven by venturi eect such that suction of the low energetic ow is carried through low pressure region obtained by high energetic ow and both high energetic ow and sucked ow can be inject for ow control as shown gure 2.3.…”

Section: Blowingmentioning

confidence: 99%

Passive Flow Control in Boundary Layer Ingesting Semi Submerged Inlet

Küçük¹,

Baran²,

Uzol³

2015

51st AIAA/SAE/ASEE Joint Propulsion Conference

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Submerged intake designs with high compactness provide lower radar cross sectional area, less noise, higher packaging eciency and lower drag compared to the conventional designs. However, in such an intake ow exposed to strong adverse pressure gradients both in streamwise and circumferential directions due to the centerline curvature and high diusion rate through the intake. Since, ow inside submerged intakes is very sensitive to the upcoming ow quality, it is very common to encounter with high total pressure distortion and low total pressure recovery inside boundary layer ingesting submerged intakes. Therefore, ow control methods used for reducing distortion and/or increasing pressure recovery can provide crucial advantageous to the intake designers. In this thesis, eect of vortex generators used as a passive ow control devices in a semi submerged boundary layer ingesting intake is computationally investigated with commercially available ow solver Fluent 14.0. In order to reach high condence about v computational strategy and turbulence model selection validation study is conducted with an available experimental data in the open literature for a serpentine intake with and without vortex generator application. Validation results indicate that κ − ω SST provide more accurate results compared to the computations obtained with Spalart Allmaras and Realizable κ − ε turbulence models. Base intake geometry developed for a ow control investigation is formed through the conventional design approaches. After computational investigation of performance of clean intake without ow control, eect of vortex generators on intake performance are investigated. Design variables of vortex generator sets are taken as vortex generator height relative to local boundary layer thickness, angle of incidence, number of vortex generators thus lateral spacing and distance between separation point and vortex generator set. Eect of the each design variable on intake performance are discussed in detail at the end of the work. Best vortex generator set provide 80% reduction in total pressure distortion with only 0.35% reduction in total pressure recovery at design condition. Moreover it is shown that, passive ow control ensure suciently uniform ow reaching engine face such that possibility of the engine surge totally eliminated with only negligible decrease in pressure recovery for not only design condition but also whole angle of attack range that mostly encountered in ight envelope.

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“…Therefore, intake/engine compatibility assessments must be addressed early in the aircraft design program to avoid extensive and expensive re-designs at later stages of the development [4]. Substantial research has been dedicated to reduce the flow distortion within these convoluted intakes with passive [5] and active [6,7] flow control, as well as through optimisation of S-duct geometries [8].…”

Section: Introductionmentioning

confidence: 99%

Assessment methods for unsteady flow distortion in aero-engine intakes

Gil-Prieto

MacManus

Zachos

et al. 2018

Aerospace Science and Technology

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Peak events of unsteady total pressure and swirl distortion generated within S-duct intakes can affect the engine stability, even when within acceptable mean distortion levels. Even though the distortion descriptors have been evaluated in S-duct intakes, the associated flow field pattern has not been reported in detail. This is of importance since engine tolerance to distortion is usually tested with representative patterns from intake tests replicated with steady distortion generators. Despite its importance in intake/engine compatibility assessments, the spectral characteristics of the distortion descriptors and the relationship between peak unsteady swirl and both radial and circumferential total pressure distortion has not been assessed previously. The peak distortion data is typically lowpass filtered at a frequency associated with the minimum response time of the engine. However the engine design is not always known a priori in intakes investigations and a standard approach to reporting peak distortion data is needed. In addition, expensive and time-consuming tests are usually required to capture representative extreme distortion levels. This work presents a range of analyses based on Delayed Detached-Eddy Simulation and Stereo Particle Image Velocimetry data to assess these aspects of the unsteady flow distortion. The distorted pattern associated with different swirl distortion metrics is identified based on a conditional averaging technique, which indicates that the most intense swirl events are associated with a single rotating structure.. The main frequencies of the flow distortion descriptors in a representative S-duct intake are found to lie within the range in which the engine stability may be compromised. The peak total pressure and swirl distortion events are found to be not synchronous, which highlights the need to assess both types of distortion. Peak swirl and total-pressure distortion data is reported as a function of its associated time scale in a more general way that can be used in the assessment of intake unsteady flow distortion. Extreme Value Theory has been applied to predict peak distortion values beyond those measured in the available dataset, and whose measurement would otherwise require testing times two orders of magnitude longer than those typically considered.

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Effectiveness of vortex generator jets and wall suction on separated flows in serpentine-duct diffuser

Cited by 18 publications

References 18 publications

Numerical Simulations of Fan/Airframe Interaction with Active Flow-Control

Numerical Simulations of Fan/Airframe Interaction with Active Flow-Control

Passive Flow Control in Boundary Layer Ingesting Semi Submerged Inlet

Assessment methods for unsteady flow distortion in aero-engine intakes

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