An overview of flow control activities at Dassault Aviation over the last 25 years

2016 ◽  
Vol 120 (1225) ◽  
pp. 391-414
Author(s):  
J.-P. Rosenblum
Keyword(s):  
Flow Control ◽  
The United States ◽  
Control Flow ◽  
Boundary Layer Transition ◽  
Layer Transition ◽  
Flow Separation Control ◽  
Research Activities ◽  
Flow Control Devices ◽  
Laminar Flow Control ◽  
Control Technologies

ABSTRACTIn France, the very first ideas on flow control were developed by Philippe Poisson-Quinton from the Office National d'Etudes et Recherches Aérospatiales (ONERA) in the 1950s. There was some renewal of this research topic in the early 1990s, first in the United States with scientists like Wygnanski and Gad-El Hak, and also in France at the initiative of Pierre Perrier from Dassault Aviation, who triggered a lot of research activities in this field both at ONERA and in the French National Centre for Scientific Research (CNRS) laboratories. The motivation was driven by the applications on Dassault Aviation military aircraft and Falcon business jets in order to contribute to the design, while facilitating performance optimisation and multi-disciplinary compromise. A few examples of flow control technologies, such as forebody vortex control, circulation control, flow separation control or boundary layer transition control using hybrid laminar flow control (HLFC), are presented to illustrate the applications and to explain the methodology used for the design of the flow control devices. The author also emphasises the current reaction of industry with respect to the integration of flow control technologies on an aircraft programme. The conclusion is related to the present status of the French research on this topic and to the next challenges to be addressed.

Status and perspectives of laminar flow

2005 ◽  
Vol 109 (1102) ◽  
pp. 639-644 ◽  
Author(s):  
G. Schrauf
Keyword(s):  
Boundary Layer ◽  
Laminar Flow ◽  
Flow Control ◽  
Boundary Layer Transition ◽  
Technology Readiness ◽  
Layer Transition ◽  
The Status ◽  
Natural Laminar Flow ◽  
Laminar Flow Control

AbstractAfter identifying the ecological and economic drivers for use of laminar flow technology, we outline the mechanisms of laminarturbulent boundary layer transition and review the status of natural laminar flow (NLF) and hybrid laminar flow control (HLFC). New ways to reduce the complexity of HLFC systems are presented, and the remaining steps to achieve technology readiness are discussed.

scholarly journals On the Anomalous Counterclockwise Turning of the Surface Wind with Time in the Plains of the United States

2018 ◽  
Vol 146 (2) ◽  
pp. 467-484 ◽  
Author(s):  
Howard B. Bluestein ◽  
Glen S. Romine ◽  
Richard Rotunno ◽  
Dylan W. Reif ◽  
Christopher C. Weiss
Keyword(s):  
United States ◽  
Boundary Layer ◽  
Great Plains ◽  
Surface Wind ◽  
Vertical Mixing ◽  
The United States ◽  
Time Of Day ◽  
Boundary Layer Transition ◽  
Vertical Shear ◽  
Layer Transition

Vertical shear in the boundary layer affects the mode of convective storms that can exist if they are triggered. In western portions of the southern Great Plains of the United States, vertical shear, in the absence of any transient features, changes diurnally in a systematic way, thus leading to a preferred time of day for the more intense modes of convection when the shear, particularly at low levels, is greatest. In this study, yearly and seasonally averaged wind observations for each time of day are used to document the diurnal variations in wind at the surface and in the boundary layer, with synoptic and mesoscale features effectively filtered out. Data from surface mesonets in Oklahoma and Texas, Doppler wind profilers, instrumented tower data, and seasonally averaged wind data for each time of day from convection-allowing numerical model forecasts are used. It is shown through analysis of observations and model data that the perturbation wind above anemometer level turns in a clockwise manner with time, in a manner consistent with prior studies, yet the perturbation wind at anemometer level turns in an anomalous, counterclockwise manner with time. Evidence is presented based on diagnosis of the model forecasts that the dynamics during the early evening boundary layer transition are, in large part, responsible for the behavior of the hodographs at that time: as vertical mixing in the boundary layer diminishes, the drag on the wind at anemometer level persists, leading to rapid deceleration of the meridional component of the wind. This deceleration acts to turn the wind to the left rather than to the right, as would be expected from the Coriolis force alone.

scholarly journals Plasma-Actuated Flow Control of Hypersonic Crossflow-Induced Boundary-Layer Transition

AIAA Journal ◽  
2020 ◽  
Vol 58 (5) ◽  
pp. 2093-2108
Author(s):  
Harrison B. Yates ◽  
Eric H. Matlis ◽  
Thomas J. Juliano ◽  
Matthew W. Tufts
Keyword(s):  
Boundary Layer ◽  
Flow Control ◽  
Boundary Layer Transition ◽  
Layer Transition

Separated Flow Transition on an LP Turbine Blade With Pulsed Flow Control

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Jeffrey P. Bons ◽  
Daniel Reimann ◽  
Matthew Bloxham
Keyword(s):  
Boundary Layer ◽  
Flow Control ◽  
Turbine Blade ◽  
Separation Bubble ◽  
Operating Conditions ◽  
Boundary Layer Transition ◽  
Single Element ◽  
Layer Transition ◽  
Flow Measurements ◽  
Pulsed Flow

Flow measurements were made on a highly loaded low pressure turbine blade in a low-speed linear cascade facility. The blade has a design Zweifel coefficient of 1.34 with a peak pressure coefficient near 47% axial chord (midloaded). Flow and surface pressure data were taken for Rec=20,000 with 3% inlet freestream turbulence. For these operating conditions, a large separation bubble forms over the downstream portion of the blade suction surface, extending from 59% to 86% axial chord. Single-element hot-film measurements were acquired to clearly identify the role of boundary layer transition in this separated region. Higher-order turbulence statistics were used to identify transition and separation zones. Similar measurements were also made in the presence of unsteady forcing using pulsed vortex generator jets just upstream of the separation bubble (50% cx). Measurements provide a comprehensive picture of the interaction of boundary layer transition and separation in this unsteady environment. Similarities between pulsed flow control and unsteady wake motion are highlighted.

Separated Flow Transition on an LP Turbine Blade With Pulsed Flow Control

2006 ◽  
Author(s):  
Jeffrey P. Bons ◽  
Daniel Reimann ◽  
Matthew Bloxham
Keyword(s):  
Boundary Layer ◽  
Flow Control ◽  
Turbine Blade ◽  
Separation Bubble ◽  
Operating Conditions ◽  
Boundary Layer Transition ◽  
Single Element ◽  
Layer Transition ◽  
Flow Measurements ◽  
Pulsed Flow

Flow measurements were made on a highly loaded low pressure turbine blade in a low-speed linear cascade facility. The blade has a design Zweifel coefficient of 1.34 with a peak pressure coefficient near 47% axial chord (mid-loaded). Flow and surface pressure data were taken for Rec = 20,000 with 3% inlet freestream turbulence. For these operating conditions, a large separation bubble forms over the downstream portion of the blade suction surface, extending from 59% to 86% axial chord. A Single-element hotfilm measurements were acquired to clearly identify the role of boundary layer transition in this separated region. Higher-order turbulence statistics were used to identify transition and separation zones. Similar measurements were also made in the presence of unsteady forcing using pulsed vortex generator jets just upstream of the separation bubble (50% cx). Measurements provide a comprehensive picture of the interaction of boundary layer transition and separation in this unsteady environment. Similarities between pulsed flow control and unsteady wake motion are highlighted.

scholarly journals Transition Effect on the Flow Dynamics in a Compressor Blade Passage

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Ryszard Szwaba ◽  
Piotr Kaczynski ◽  
Janusz Telega
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Flow Control ◽  
Flow Dynamics ◽  
Boundary Layer Transition ◽  
The Other ◽  
Control Methods ◽  
Layer Transition ◽  
Blade Passage ◽  
Transition Control

An experimental investigation was carried out to study the effect of the boundary layer transition on the flow dynamics in the blade passage of a compressor cascade. A model of a turbine compressor passage was designed and assembled in a transonic wind tunnel for this purpose. Two different flow control methods were used in the experiment to induce the transition upstream of the shock wave, one concerning the microstep application and the other using distributed roughness strips. Two locations of spanwise microsteps for the transition trigger were chosen, one at the leading edge and the other closer to the shock wave position. The distributed roughness in the form of standard sandpaper strips with different heights was applied in three various locations on the blade upstream of the shock. The main objective of investigations is to present the influence of the laminar and turbulent shock wave-boundary layer interaction on the flow dynamics in a compressor fan passage, and the specific objective is to show how the parameters of particular transition control methods affect the flow dynamics in the investigated channel. The major challenge for this research was to minimize the disturbance caused by the microstep or roughness to the laminar boundary layer, while still ensuring a successful transition. Very interesting results were obtained in the flow control application for the boundary layer transition control, demonstrating a positive effect on the flow unsteadiness in changing the nature of the interaction.

On Exploring Application of MEMS in Aerodynamic Flow Control

2006 ◽  
Author(s):  
Jin-Jun Deng ◽  
Wei-Zheng Yuan ◽  
Bing-He Ma ◽  
Kui Liu ◽  
Yan Wang
Keyword(s):  
Flow Control ◽  
Flexible Substrate ◽  
Sensor Arrays ◽  
Leading Edge ◽  
Flow State ◽  
Flow Separation Control ◽  
Research Activities ◽  
Sensors Array ◽  
Realtime Measurement ◽  
Aerodynamic Flow Control

This paper presents an overview of research activities in MEMS/NEMS Lab of NWPU on applying MEMS to aerodynamic flow control domain. For the purpose of flow separation control, a kind of bubble actuator array was developed and fabricated. By mounted on the leading edge of the aerofoil, its feasibility for flow control has been demonstrated through wind-tunnel tests. In order to obtain flow state and determine the best actuation location for micro-actuator array, micro shear-stress sensor arrays have been investigated. An integration method of micro-sensors array was developed based on flexible PCB technology. Using this flexible substrate, micro-sensor arrays can be attached upon the surface of aircraft key position to realize distributed and realtime measurement of flow parameter.

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