Document
Low-Re Testing of Swept Wing with Ice
Initial Low-Reynolds Number Iced
Aerodynamic Performance for CRM Wing
Brian Woodard, Jeff Diebold
University of Illinois at Urbana-Champaign
Andy Broeren, Mark Potapczuk
NASA Glenn Research Center
Sam Lee
Vantage Partners, LLC
Michael Bragg
University of Washington
SAE Icing Conference Prague, Czech Republic June 22-25, 2015
Low-Re Aerodynamic Testing
Low-Re Testing of Swept Wing with Ice
Goals
Low-Re Testing of Swept Wing with Ice
• Overall Project Goal
– Improve the fidelity of experimental and computational simulation methods for swept-wing ice accretion formation and the resulting aerodynamic effect
• Goal of Low-Reynolds Number Aerodynamic Testing
– Develop low-cost test capability for iced swept wings – Quantify the differences in aerodynamic performance and key flowfield features between the low- and high-Re testing
• Goal of Initial Low-Re Wind Tunnel Entry (this work)
– Evaluate splitter plate effects – Evaluate roughness effects – Provide recommendations for high-Re testing
Wing Model
Low-Re Testing of Swept Wing with Ice • Semispan Common Research Model (CRM)-based wing – 8.9% scale of the full-scale reference – Zero-g loading and zero dihedral Leading Edge Semispan MAC Aspect Taper Ratio Sweep Ratio 37.2 ° 1.5 m 0.41 m 8.3 0.23 • Removable leading edge • Leading-edge configurations – Clean aluminum – Rapid prototyped (RPM) clean – RPM horn ice – RPM roughness – Grit roughness Model installed in wind tunnel • Several splitter plate variations with removable leading edge
Wind Tunnel Facility
Low-Re Testing of Swept Wing with Ice
• Walter H. Beech 7x10 ft
wind tunnel at Wichita St.
University
• Atmospheric, closed-
return type tunnel
• Test Conditions for these
tests: – M = 0.09, Re = 0.8×10 – M = 0.18, Re = 1.6×10 – M = 0.27, Re = 2.4×10 Model installed in wind tunnel with circular splitter plate and clean leading edge
Leading Edge Configurations
Low-Re Testing of Swept Wing with Ice • Full span clean aluminum leading edge • RPM leading edges mounted in 6 spanwise segments CAD model of • Horn ice shape simulation based clean leading edge on LEWICE3D predictions Pressure taps Horn ice example 2D example of ice shape
RPM Roughness
Low-Re Testing of Swept Wing with Ice • Heights (k) of 0.01 and 0.02 inches • Coverage extent along leading edge determined from LEWICE3D RPM Simulated Roughness calculations • Manufactured using Stereolithography (SLA) 3D printing Roughness size/height (k) = radius of hemisphere Element spacing = 1.3 x diameter Not to scale
Grit Roughness
Low-Re Testing of Swept Wing with Ice • Heights (k) of 0.005, 0.01, and 0.02 inches • Coverage extent the same as RPM • Silicon carbide • Applied using double-sided tape Grit Roughness Grit roughness applied to model Comparison to full scale: k/c Application CRM65 Roughness Low -Re Roughness mac Configuration Size (mm) Size (mm) -4 1.43 0.13 3.1 x 10 Grit -4 RPM/Grit 2.85 0.25 6.3 x 10 -4 5.71 0.51 RPM/Grit 12.5 x 10
Ice Shape Installation
Low-Re Testing of Swept Wing with Ice 6 spanwise segments of removable leading edge Upper surface RPM segment installed on model
Splitter Plate
Low-Re Testing of Swept Wing with Ice • Model designed for installation with a splitter plate – Allows model to be tested in different facilities – Reduces influence of different floor boundary layers • Investigated several configurations: – Wing mounted directly to floor – Circular plate, Circular shroud – Circular plate, Streamlined shroud – Rectangular plate, Streamlined shroud Rectangular plate, Streamlined shroud Circular shroud Streamlined shroud Circular plate, Circular shroud
Effect of Splitter Plate
Low-Re Testing of Swept Wing with Ice Clean LE, Re = 2.4 x 10 , M = 0.27 Circular plate and streamlined shroud selected for baseline case.
Baseline Clean
Low-Re Testing of Swept Wing with Ice Clean LE, Circular Splitter Plate, Streamlined Shroud
CFD Comparison
Low-Re Testing of Swept Wing with Ice • ANSYS Fluent viscous simulation of baseline clean model case • No splitter plate, no shroud
Surface Pressure Comparison
Low-Re Testing of Swept Wing with Ice Lines are CFD • Angle of attack of 10° Squares are wind tunnel data • Overall agreement between CFD and pressure tap data is good – Attachment line location matches well – Pressure tap resolution may not be high enough to accurately capture suction peak Spanwise Station
RPM Clean and Ice
Low-Re Testing of Swept Wing with Ice Circular Splitter Plate, Streamlined Shroud Re = 2.4 x 10 , M = 0.27 RPM “Clean” LE consists of 6 spanwise segments with no ice shape or roughness
RPM Roughness
Low-Re Testing of Swept Wing with Ice Circular Splitter Plate, Streamlined Shroud Re = 2.4 x 10 , M = 0.27
Grit Roughness
Low-Re Testing of Swept Wing with Ice Circular Splitter Plate, Streamlined Shroud Re = 2.4 x 10 , M = 0.27
Grit and RPM Roughness Compared
Low-Re Testing of Swept Wing with Ice Circular Splitter Plate, Streamlined Shroud Re = 2.4 x 10 , M = 0.27
Surface Oil Flow: Clean Wing
Low-Re Testing of Swept Wing with Ice Circular Splitter Plate, Streamlined Shroud Re = 2.4 x 10 , M = 0.27 Clean wing, α = 0 ° Clean wing, α = 12 °
Oil Flow: Comparison of Clean and Ice
Low-Re Testing of Swept Wing with Ice Circular Splitter Plate, Streamlined Shroud Re = 2.4 x 10 , M = 0.27 Leading-Edge Vortex Clean wing, α = 8 ° Ice wing, α = 8 °
Conclusions
Low-Re Testing of Swept Wing with Ice
• Aerodynamic
– Splitter plates • Aerodynamic differences between configurations were minimal • Circular splitter plate with streamlined shroud selected – Roughness • For the tested conditions, all roughness configurations had the same impact on the performance of the wing – 15% reduction in C at 12° angle of attack L – 100% increase in C at 12° angle of attack D • Rapid prototyped manufacturing techniques are capable of capturing ice roughness details (down to a height of 0.010 inches)
• Practical
– Working with multiple spanwise removable segments is challenging especially with pressure taps – Future iterations will have fewer spanwise segments
Future Work with this Model
Low-Re Testing of Swept Wing with Ice • Full-scale ice shapes acquired for spanwise segments of this model geometry in the NASA Icing Research Tunnel during spring 2015 • Those ice shapes will be extrapolated to create full-span ice shapes for this model • Low-Re testing will resume with those high fidelity ice shapes in the spring of 2016 • The same experimental techniques presented here will be employed with the addition of a wake survey
Questions?
Low-Re Testing of Swept Wing with Ice
• Acknowledgments
– FAA Grant 10-G-004
– Technical monitor: Dr. James Riley
– Gustavo Fujiwara and Brock Wiberg for their
assistance with the CFD simulations