systems architecture and implementation costs of …...systems architecture and implementation costs...

1Airbus DiPaRT 2017 Flight Physics Symposium

Systems Architecture and Implementation Costs of Sweeping Jet Actuators for Separation Control

Dr Mark JabbalUniversity of [email protected]


Motivation

• Future aircraft will potentially improve efficiency through active flow control (AFC) technology

• There is a need to develop a systems approach to flow control, in order to understand systems costs associated with the application of AFC systems to civil transport aircrafto Flow control effectiveness alone is not enough…if the performance benefits are

modest and the costs are high, you need to fully understand the costs

• Some key issues to be addressed:o What is the most cost effective means of distributing power to AFC actuators?o How does AFC actuator efficiency and geometric layout affect power and mass

requirements of the overall system?


Background: related studies• McLean et al. (1999)

o Separation control via unsteady excitation• Crowther & Gomes (2008)

o SJA systems architecture and costs• Liddle, Jabbal & Crowther (2009)

o AFC systems and certification issues• Jabbal, Crowther & Liddle (2010)

o SJA, PJA, active dimple and plasma systems architectures and costs• Jabbal & Valerio (2014)

o AFC system sensitivity and configuration design• Meyer, Machunze & Bauer (2014)

o Systems ground tests• Mooney et al. (2014)

o AFC-enabled vertical tail system integration• Jabbal, Everett, Krishnan & Raghu (2016)

o HLFC systems architecture cost/benefit


Aim of present work

To understand the associated systems costs of incorporating an array of sweeping jet actuators in an Airbus A320 aircraft for the purpose of controlling boundary layer separation along the trailing edge flap

SlotsTE flap

Aircraft Wing

Blown air from slots


Sweeping Jet Actuators (SWJAs)Sweeping jet actuators (SWJAs), or fluidic oscillators, are based on the bi-stable states of a jet of fluid in a cavity caused by inherent instabilities (feedback free) or a specially designed feedback path

Feedback-free SWJA – an input fluid jet pair interact in the cavity to create an oscillatory or ‘sweeping’ jet output

Wall attachment, or feedback SWJA, makes use of the Coandaeffect for jet motion


Sweeping Jet Actuators (SWJAs)

• No moving parts;• Oscillating jet (1-20 kHz);• High authority (sonic exit velocity);• Low mass flow rate (~1 g/s);• Meso-scale nozzle (200 µm – 1 mm)

• Relatively high TRL compared with other AFC fluidic devices (SJAs, PJAs) led to their selection for full-scale testing on the B757 vertical tail ‘ecoDemonstrator’ program


Flow control systems architectures

• In order to assess AFC systems costs, it is useful to define the overall systems architectures required to support AFC integration into civil transport aircraft

• ‘Architecture’ is defined to be the combination of an AFC actuator technology and the means of delivering power to it

• An AFC systems architecture specifically consists of generation, management, distribution and actuator subsystems


Power distribution systems

Pneumatic SystemHybrid (Electric-Pneumatic) System


More Electric Aircraft (MEA)

MEA – replacement of pneumatic/hydraulic systems by electrically powered systems

• Boeing 787 and Airbus A380 have significantly larger electrical systems, which has led to the advancement in technology in electrical systems

• Major breakthroughs in power electronics technology –electromechanical actuators (EMA), electro-hydrostatic actuators (EHA), fault tolerant electric motor/generator, and power converters


Electric vs. Pneumatic power distribution

a) Diameter (height)

Comparison between aircraft grade electric cabling (MIL-W-22759/34) and pneumatic/ECS ducting (SIL2-2001)

Maximum distribution diameter defined by LE wing anti-icing duct (~50 mm)Airbus DiPaRT 2017 Flight Physics Symposium


Electric vs. Pneumatic power distribution

Electrical power distribution has clear benefits over pneumatic power distribution in terms of reduced mass, reduced volume installation and higher efficiency for a given level of power transmission

c) Efficiencyb) Mass per unit length


AFC system mass model

[ ]tmmWm WgWF !+S= )(hh

• The present work uses a scalable, low-order system mass model to capture the important design trades

• The model includes a mass term due to systems hardware and a mass term due to the system energy usage:

o m = overall AFC system architecture mass (kg)o WF = total fluidic output power (kW)o h = overall efficiency of AFC system (generation, distribution, actuation)o mW = hardware power specific mass (kg/kW)o mWg = power specific fuel consumption of generator (kg/s/kW)o t = duration of AFC operation (s)

• Power specific mass terms are estimated using aircraft equipment supplier information coupled with analytical physics


AFC system mass model


SWJA systems architectureSundstrand IDG115 VAC; 400 Hz61 kg; 90 kWmw = 0.68 kg/kW

Electrical-driven compressor0.14 kg; 0.15 kW;h = 74%mw = 1.24 kg/kW

Advanced Fluidics SWJA2 g; 0.06 kWmw = 0.05 kg/kW

GCU/ELCU/TRUmw = 0.27 kg/kW

XL ETFE cable600 Vh = 94%m'wd = 3´10-3 kg/kWm


SWJA parameters and layoutAdvanced Fluidics SWJA Specification

Jet exit dimensions 1 x 1.5 mmJet exit depth 1 mmPlenum chamber depth 1 mm

Plenum chamber width 12 mm

Spanwise spacing 25 mmMass flow rate 1 g/s per actuatorJet exit velocity up to sonic speeds


Aircraft parameters and application conditions

Aircraft SpecificationAircraft A320-200MTOW 75,000 kgMcruise 0.78MAC 4.29 mWingspan 34 mWing area 123 m2

Operational ConditionsArray chordwise location

Array spanwise extent, sA

Mach number Velocity, U¥

Boundary layer, d Air density, r

25% flap 73% (24 m) 0.45 150 m/s 6 mm 1.2 kg/m3


AFC model variables and assumptions

• SWJA operating conditions for separation control were chosen based on empirical evidence for effectivenesso Peak jet-to-free stream velocity ratio, VR = 1, 2, 3o Ratio of SJWA spanwise spacing to SWJA nozzle width, l = 8, 17, 25o SWJA nozzle efficiency, h = 60, 70, 80%o Ratio of SWJA nozzle width to local boundary layer height, D = 0.16o Duration of AFC operation (off-design flight – initial climb & approach), t = 10 mins

• To produce a scalable model, the mass cost of the hardware is assumed to be proportional to the power flowing through the system

• System redundancy costs are not considered

( ) 33

21

4 ¥D

= UsVRW AF drl

p


AFC system mass and power requirement

Impact of SWJA spanwise spacing for fixed SWJA efficiency (h=70%)

As a percentage of TE flap mass (638 kg), AFC mass varies from 4% to 150%


AFC system mass and power requirement

Impact of SWJA efficiency, h, for fixed SWJA spanwise spacing (l=17)

As a percentage of TE flap mass (638 kg), AFC mass

varies from 6% to 85%


Conclusions

• AFC system costs are key issues that, in addition to effectiveness, will determine application to civil transport aircraft

• Low-order based approach for estimating the mass and power costs of AFC systems has been developedo Tools allow useful conclusions to be drawn on the relative costs of different AFC systems

architectures, and sensitivities within each AFC system architecture

• Future developmentso Safety and certification systems costs, e.g. redundancy o Collaboration with DLR Institute of Flight Systems to develop and compare different

systems approaches to flow control: higher-order modelling for improved fidelity; overall cost/benefit considerations

21

Advanced Fluidics LLC is extensively involved in the development of SWJAs for AFC, since their first use as windscreen washer jets

Airbus DiPaRT 2017 Flight Physics Symposium

Work in collaboration with DLR Institute of Flight Systems and Advanced Fluidics LLC

systems architecture and implementation costs of …...systems architecture and implementation costs...

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