Application of Pneumatic Aerodynamic Technology to Improve Drag Reduction, Performance, Safety, and Control of

Advanced Automotive Vehicles by Robert J. Englar, Georgia Tech Research Institute

Application of Pneumatic Aerodynamic Technology to Improve Drag Reduction, Performance, Safety, and Control of

Advanced Automotive Vehicles by Robert J. Englar, Georgia Tech Research Institute

Application of Advanced Pneumatic Aircraft Technology….

...Through Analytical &Experimental Development ...

..To Proof-of-ConceptFull-Scale Tests

Outline of Presentation

• Introduction: Pneumatic Heavy Vehicle Aerodynamic Technology• Pneumatic Heavy Vehicles (PHV)….Multi-Purpose Aero Devices for: Force & Moment Reductions or Augmentations Drag Reduction (Fuel Efficiency) or Drag Increase (Aero Braking) Increased Stability (Directional & Lateral) Improved Safety of Operation Reduced Spray Turbulence & Hydroplaning No-Moving-Part Integrated System Pneumatic Cooling System • Wind-tunnel Investigations &Confirmations• Initial Full-Scale Tuning Tests at Volvo Trucks • SAE Type II Fuel Economy Tests at TRC• Other Applications: Pneumatic SUV & Aero Heat Exchanger• Conclusions: Summary of Wind-Tunnel & Full-Scale Results

Basics of Circulation Control Pneumatic Aerodynamics and Application to Heavy Vehicles

Circulation Control Concept on Aircraft Navy A-6/CCW Flight Test Aircraft

Blowing on Front of Trailer and/or All 4 Trailing Edges

Pneumatic Aero Development at GTRI Showed 50%(or more) Drag Reduction, Force & Moment Augmentation from Blown Configurations, and

Drag Increase for Aero Braking if Desired

4 Blown Slots & Jet Turning on Rear Doors of Wind-Tunnel Model

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

CD

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20Momentum Coefficient, C

0.065-Scale GTRI Blown Heavy Vehicle Drag &Aero Modifications; 0.375"R Circular Arc 90°TE , Wheels on, q=11.86 psf, V=70 mph, =0°, =0°

CD=0.627

CD=0.824

Top & Bottom Slots Only=Drag Increase for Braking

All Four 90° Slots Blown= Drag Reduction

Unblown Baseline,No Gap,Square LE+TE

Unblown Baseline, Unfaired,Full Gap

Side Slots Only=Yaw orAnti-Yaw

Blown Truck,Low Cab, No Gap,Round Top LE, 0.375"R, 90° TE

90°/30° 1/2"plte TE, All 4 Slots Blown

0.25 psig

0.5 psig0.75 psig

1.0 psig

CD Due toGAP

CD Due to RoundedUnblown LE&TE

-23.9%

-10.2%

CD due to Blowing-26.8%

GTRI Extended C Tests Showed State-of-the-Art Drag Reduction!!

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

CD

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Momentum Coefficient, C

h=0.01", 0.375"R Circular Arc 90°/30°1/2"TE, LE & TE Blowing, Wheels on,

Cab/Trailer Gap Plates E Installed, =0°, =0°

q=6.1 psf, V=51 mph

q=11.9, V=70.9 mph,

q=25 psf,V=103.0 mph

Unfaired UnblownBaseline HV, C D=0.824

BlownHeavyVehicle

CD=0.29

CD=0.33

CD=0.25

1999 Ferrari 550

1999 Corvette Coupe

2001 Honda Insight

Directional Control Capability Provided by Blowing of

Left Side Slot Only (Similar Effects on Drag)

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

CN =Half Chord Yawing Moment Coefficient

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20Momentum Coefficient, C

90°/30° 1/2"plate TE , 0.375"R=0°, Wheels ON, Left Slot Blowing Only

Nose Right

Nose Left

=-8°, Nose Yawed Left

=0°, Nose Straight Ahead

Yawing MomentTrimmed by Blowing

Blowing Produces ExcessYaw in Opposite Direction

CN

UNSTABLE

Additional Gain from Side Blowing =Reduced CD due to Yaw

Yaw Nose Left, Blow HERE

Static Jet Turning Displayed During Full-scale Run-up Testing

Setting Slot Heights and Confirming Jet Turning at Low Blowing Rate on Aft Door of Trailer

Right Rear Corner, looking up--Tufts Show Jet Turning to Left:

90° on Side and 30° on Top

Slots, 4 total, one per side

Tufts

On-the-Road Operation: Jet Turning Entraining the Freestream Flowfield and Reducing Vehicle Drag

Rear View with Jets Blowing

Close-up of Tufts Showing Jet Turning

Pneumatic Heavy Vehicle (PHV) Test Rig on Track for Fuel Test 1 at TRC, 75 mph with Blowing

SAE Fuel Test I Results: 5-6% Fuel Economy Increase ~ 10-12% CD Reduction New Wind Tunnel Tests wereConducted to Identify Initial Problem areas, then Fuel Test II was conducted in Sept. 2004

Updated PHV Blown Wind-tunnel Model to Resemble TRC Test Rig,

With New Tractor, New Top Strut Mount, New TE Geometry

Airfoil Airfoil

New Blown Trailing-edge Geometry,

53’ Trailer

High Floor, Wheels & Undercarriage Details, No Fairing

Generic Conventional Model (GCM) Cab(DOE Team design)

Faired Mounting Strut

Air Supply Line

Optional Gap Side Plates

Tests of this new model completed at GTRI; Showed 31% Lower CD than Stock Truck

Second SAE Type II Fuel Economy Test at TRC

Revised Pneumatic Heavy Vehicle Test Rig

Baseline Stock Heavy Vehicle Control Truck

SAE Fuel Economy Results at TRC, Test 2 - Improvements due to Blowing and Aft Trailer Geometry

0

2

4

6

8

10

12

14

%FEI=% Chng in MPGfrom Base-line HV

0 0.01 0.02 0.03 0.04 0.05

Momentum Coefficient C

TRC On-Track (9/04) SAE Type -II Fuel Economy Test Results

(Blower fuel not included.except as noted)

PHV Total, V=65mph

PHV Total, V=75mph

PHV, Blowing Only,V=65mph

PHV, Blowing Only,V=75mph

T/C = 1.00 forBaseline ReferenceTruck

PHV Total FuelIncluded, PulsedBlowing, V=75mph

PHV Total, FuelIncluded, PB,V=65mph

Estimated%FEI fromWind-tunnelData

Fuel Usage in the US (look at SUVs), and One Possible Fix:Increase Fuel Efficiency of SUVs

DOE Fuel Usage Data, 109 gallons/year Blown SUV in Lockheed Tunnel

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

110.0

120.0

130.0

140.0

150.0

160.0

BGY

1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020Year

(Source: Refs. 12 and 13)

Total Fuel Consumed

Domestic Oil Production

Autos

Light Trucks, SUVs(Class 1&2a)

Heavy Trucks (Class 2b-8) & Buses (No Military Vehicles)Report Date

"Gap"

BGY=Billions of Gallons per Year

Full-Scale Tunnel Tests of Unblown SUV to Locate Flow Separation for Blowing Slot Location of Pneumatic SUV

Smoke Flow over Unblown SUV ,Testing in Lockheed 16’ x 23’ Low Speed Wind Tunnel, Marietta GA

Separated Flow over Aft Door of SUV

Pneumatic Capabilities of Blown SUV Confirmed in WT Test;Blowing Configs far from Optimized

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

Cyaw

0 0.01 0.02 0.03 0.04 0.05 0.06

Left Slot Momentum Coefficient, C

LSWT Test 1853, Run 17, Left Side Slot ONLY, V=50 mph, All Jet Turning Corners are 45°

NoseRight Cyaw required to offset =-15° unblown

Cyaw required to offset =-10° unblown

Cyaw required to offset =-5° unblown

0.44

0.46

0.48

0.50

0.52

0.54

0.56

CD

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

Momentum Coefficient, C

PSUV Drag Variation with Blowing, V=50mph(Blowing Geometry not yet Optimized)

Run 12, 45° Top, Bottom & Bottom Sides; 90° Top Sides

Run 11, 45° Top & Bottom; 90° Sides

Run 14, 45° All Sides

Drag Reduction or Aero Braking~Functions Interchangeable: Which Slot Blown

Directional Stability,No Moving Parts

CONCLUSIONS: Pneumatic Aerodynamic Concepts Now Demonstrated Full-Scale on PHV and PSUV

Blowing Demonstrated on Full-Scale PHV Tests at TRC, Confirming Drag Reduction, but less than from Tunnel Tests; Reasons Now Identified

15-16% Fuel Efficiency Improvement is PossibleBased onModelCD Reduction ~TRC Track Test Results Show 11-12% Fuel Economy Increase due to Blowing and Aft Geometry (not including blower fuel; better blower or pump would help) Pneumatic Yaw Stability, Side-Wind CD Reduction, and Aero Braking Capabilities

(Safety of Operation) are Confirmed, Model & Full-scale Testing

Pneumatic Full-scale Tunnel Tests Showed Similar Blown Capabilities for SUVs

• Let’s get this on Production Trucks & Fleets!! (12%FEI=2.4 Billion gals of diesel/yr)

GTRI PATENTED CONCEPTS

BACKUP Slides

The Effects of Blowing on Increasing Base Pressure for CD Reduction

TheVertical Mid Base

Vertical Mid Base

Horizontal Mid Base

Flow Visualization of Blowing Jets

Tuft Showing Flow Uniformity at Diffuser Center

Combined Jet Strength and Wake Contraction (see Shirt)

Blowing Efficiency & Drag/Thrust Increment Due to Blowing Slot Position, shown as Fraction/Multiple of Blowing Momentum Input

-5.5

-5.0

-4.5

-4.0

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

CD/C

-0.15-0.12-0.09-0.06-0.03-0.000.030.060.090.120.15

CD = CD-CD0

Low Cab, No Gap, Round LE,0.375"R Circular Arc 90°TE, q=11.86psf, V=70mph , =0°, Re=2.5 x 10**6

Note: CD0 = CD at C=0

All 4 SlotsBlown

Bottom Slot OnlyTop & BottomSlots

Top Slot Only

2 Side Slots Only

90/30°,1/2"plate TE, All 4 Slots Blown

CD/CMomentum Recovery

Figure 6 - Blowing Efficiency & Drag Increments due to Blowing Slot Location

It’s possible to get back 5.5 times the C input as a CD Reduction….

OR 2 times the C input as Aero Braking increase