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

Transcription

1 Systems Architecture and Implementation Costs of Sweeping Jet Actuators for Separation Control Dr Mark Jabbal University of Nottingham 1

2 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 aircraft o 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? 2

3 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 3

4 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 TE flap Slots Aircraft Wing Blown air from slots 4

5 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 Coanda effect for jet motion 5

6 Sweeping Jet Actuators (SWJAs) 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 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) 6

7 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 7

8 Power distribution systems Pneumatic System Hybrid (Electric-Pneumatic) System 8

9 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 9

10 Electric vs. Pneumatic power distribution Comparison between aircraft grade electric cabling (MIL-W-22759/34) and pneumatic/ecs ducting (SIL2-2001) a) Diameter (height) Maximum distribution diameter defined by LE wing anti-icing duct (~50 mm) 10

11 Electric vs. Pneumatic power distribution b) Mass per unit length c) Efficiency 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 11

12 AFC system mass model 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: m W = ) h [ ] m (h m t F S +! W Wg o m = overall AFC system architecture mass (kg) o W F = total fluidic output power (kw) o h = overall efficiency of AFC system (generation, distribution, actuation) o m W = hardware power specific mass (kg/kw) o m Wg = 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 12

13 AFC system mass model 13

14 SWJA systems architecture Sundstrand IDG 115 VAC; 400 Hz 61 kg; 90 kw m = 0.68 kg/kw w GCU/ELCU/TRU m w = 0.27 kg/kw XL ETFE cable 600 V h = 94% m' = kg/kwm wd Electrical-driven compressor 0.14 kg; 0.15 kw; h = 74% Advanced Fluidics SWJA 2 g; 0.06 kw m w = 0.05 kg/kw m w = 1.24 kg/kw 14

15 SWJA parameters and layout Advanced Fluidics SWJA Specification Jet exit dimensions Jet exit depth Plenum chamber depth 1 x 1.5 mm 1 mm 1 mm Plenum chamber width 12 mm Spanwise spacing Mass flow rate Jet exit velocity 25 mm 1 g/s per actuator up to sonic speeds 15

16 Aircraft parameters and application conditions Aircraft Specification Aircraft A MTOW 75,000 kg M cruise 0.78 MAC Wingspan 4.29 m 34 m Wing area 123 m 2 Operational Conditions Array chordwise Array spanwise Mach Boundary Velocity, U Air density, r location extent, s A number layer, d 25% flap 73% (24 m) m/s 6 mm 1.2 kg/m 3 16

17 AFC model variables and assumptions SWJA operating conditions for separation control were chosen based on empirical evidence for effectiveness o Peak jet-to-free stream velocity ratio, VR = 1, 2, 3 o Ratio of SJWA spanwise spacing to SWJA nozzle width, l = 8, 17, 25 o SWJA nozzle efficiency, h = 60, 70, 80% o Ratio of SWJA nozzle width to local boundary layer height, D = 0.16 o Duration of AFC operation (off-design flight initial climb & approach), t = 10 mins W F p ( ) 3 VR D 1 3 = rs du A 4 l 2 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 17

18 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% 18

19 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% 19

20 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 developed o Tools allow useful conclusions to be drawn on the relative costs of different AFC systems architectures, and sensitivities within each AFC system architecture Future developments o 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 20

21 Work in collaboration with DLR Institute of Flight Systems and Advanced Fluidics LLC Advanced Fluidics LLC is extensively involved in the development of SWJAs for AFC, since their first use as windscreen washer jets 21