Flow Visualizations and Heat Transfer Measurements in Supersonic Flow C.-C. Ting Dept. of Mechanical Engineering, National Taipei University of Technology (NTUT) Aerodynamisches Institut der RWTH Aachen, Germany (AIA)
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Flow Visualizations and Heat Transfer Measurements in Supersonic Flow
C.-C. TingDept. of Mechanical Engineering, National Taipei University of Technology (NTUT)
Aerodynamisches Institut der RWTH Aachen, Germany (AIA)
ContentsØELAC, “Two-Stage-to-Orbit System”ØThe sort of Göttingen and Trisonic Wind Tunnels, AIAØTechniques of Flow Visualization
ü Color Schlierenü Differential Interferometryü Oil Filmü Laser Light Sheet and Vapor Screen
ØThe Liquid Crystal Display Techniqueü Principleü Setupü Calibration
ØConclusionØOutlook
ELAC (Two-Stage-to-Orbit System)
ELAC
ELAC1a: only lower stage ELAC1b: lower stage and operation systemELAC1c: lower and upper stageELAC1d: complete
Upper stage
Lower stageOperation System
ELAC: The research focuses on the development of a fully reusable airplane-like space transportation system for horizontal take-off.
ELAC
ELAC Model(Elliptic Aerodynamical Configuration )
ELAC1c Model with scale 1:240
75°
EOS Model( ELAC‘s Orbital Stage )
EOS Model with scale 1:150
Casting Form
Original metal model EOS
Casting Technique
Vortices on a Deltawing
Large Angle of Attack
Vortices on a Doubledeltawing
Small Angle of Attack
Large Angle of Attack
Flow Field around ELAC1c
Flow Visualization on EOS
Figure: Shock structure and oil flow pattern at Ma=1.5 and α=3°.
Figure: Schematic of the EOS flow field.
Vortices on EOS
Wind Tunnels
The Sort of Göttingen Wind Tunnel, AIA
The Sort of Göttingen Wind Tunnel, AIA
Nozzle Test Section OperationFlow Filter
Trisonic Wind Tunnel AIA
The larger the heat transfer rate on the model surface, the colder the flow in the vicinity of the body during test runs.
Trisonic Wind Tunnel AIA
The distributions of pressure and temperature during the test runs in trisonic wind tunnel.
Trisonic Wind Tunnel AIA
HEG(High Enthalpy Shock Wind Tunnel Göttingen)
HEG
Condition (Air) I II III IV V VIReservoir Enthalpy [MJ/kg] 21.06 22.30 13.19 14.84 10.73 10.71Reservoir Pressure [MPa] 38.63 90.85 44.97 111.10 49.40 92.70Reservoir Temperature [K] 9055 9727 7279 8113 6370 6523 Mach number 9.70 9.03 9.98 9.48 9.97 9.99Free Stream Density [g/m ] 1.64 3.59 2.83 6.15 3.75 6.943
HEG
Techniques of Flow Visualization
Copyright from DLR, Germany
Supersonic Flight
Copyright from AIA, Germany
Slow Velocity Flow
Shadow
Principle of Shadow Technique
Light Source
LensFilm
Test SectionLens
Lens
The Variation of Distribution of Density, the Variation of index of Refraction.
Laser Schlieren
Light Source
LensFilm
Test Section
EdgeLensLens
Principle of Schlieren Technique
dIdxρ
∝
Principle of Schlieren Technique
DiffractionParallel Plane Light Waves
Color Schlieren
Color Schlieren Technique
Two Dimensional Photography
Parallel Light
Shock Waves
Shock Waves in Supersonic Flow
Flow
Shock Waves in Transonic Flow
Flow
Shock/Boundary Layer Interaction
Differential Interferometry Technique
Differential Interferometry Technique
Parabolic Mirror
Parabolic Mirror
Light SourcePolarization Filter
Polarization Filter
Only Polarization Filter Without Wollaston Prisma
Polarization Filter and Wollaston Prisma
Test with Thermal Flow
Setup of differental Interferometry Technique
Shock Waves in Supersonic Flow
Flow
Shock Waves in Supersonic Flow
Flow
Oil Film Technique
Flow Visualization
Setup of Oil Film Technique
Laser Light Sheet Technique
Laser Light Sheet Technique
Laser Light Sheet Technique
Double Vortices System on EOS
Flow Visualization
Film: Laser light sheet film for α = 25° and small flow velocity v = 12.69 m/sec.
Flow
Vapor Screen Technique
Argon-Ionic Laser
P =10 Watt
F = -30 mm
Test Section
Laser Light Sheet
Shifting Mirror
Flow with Humidity
photo camera
video camera
Vapor Screen Technique
Subsonic Flow Supersonic Flow
FlowFlow Visualization
Subsonic Flow Supersonic Flow
FlowFlow Visualization
Flow
Vortex on ELAC in Transonic Flow
Flow
Vortex on ELAC in Supersonic Flow
Reconstruction of Vapor Screen Results
Model
Model
Camera
Camera
Some interesting Phenomena
Embedded Shock
Flow
Deltawing
andnα nM
Embedded shock
Embedded Shock
Ma=1.5 and α=15°
Shock-Vortex Interaction
Two-dimensional vortex-shock interaction
Results from: Grasso, F and Pirozzoli, S.: Shock-Wave–Vortex Interactions: Shock and VortexDeformations and Sound Production. 1999
Film: Vapor-Screen technique at Ma=2, a=10° and x/L=70%.
Flow
Lower Stage
Upper Stage
Heat Transfer Measurement
Liquid Crystal Display (LCD) Technique
Figure: Theoretical illustration of the liquid crystal display technique.
Principle of LCD Technique
2
Figure: LCD arrangement in the trisonic wind tunnel.
Experimental Setup
Water Stream‘s DirectionT=Constant
5cmx5cm
Figure: LCD calibration setup for 1 mm aluminum plate and constant-temperature-water circuit.
Setup of LCD Calibration
Fitting Curve of LCD Calibration
Hue ≡ Wave Length
Results(ELAC1c’s Upper Surface)
The simplified equation for heat flux:
The modified Stanton number (St‘)
Table: UREOL at 20°C, where ρ is the density, c the specific heat of the model material, and λ the thermal conductivity.
The Modified Stanton Number
Ma=2, α=0°
FlowNumericExperiment
Ma=2, α=10°
Flow
Results(EOS’s Lower Surface)
The node point on the EOS nose at Ma=2.0At the center line:
Experimental Results at Ma=2.0 and α = 0°FlowFlow
FlowFlowNumerical Experimental
Experimental and Numerical Results at Ma=2.0 and α = 0°
Figure: Oil flow pattern.
Experimental Results at Ma=2.0
α = 8°
Flow Flow
Results(EOS’s Upper Surface)
Flow Visualization
Figures: Schematic of the flow field and vapor-screen results in several cross sections at Ma=2.5 and α=15°.
Flow Visualization
Flow
Film: Vapor screen film for Ma=2.0 at x/L=0.95 and α = 15°
Flow Visualization
Flow
Film: Vapor screen film for Ma=2.0 at x/L=0.7 and α = 15°
Figure: Oil flow pattern.
FlowFlowExperimental Results at Ma=2.0 and α = 0°
Experimental and Numerical Results at Ma=2.0 and α = 0°Flow
Flow Numerical Experimental
Numerical Result
Experimental Results at Ma=2.0
α = 8°
Flow Flow
Ø The heat loads and the flow field over ELAC1c and the upper stage EOS of the two-stage space transportation system ELAC were experimentally and numerically analyzed at supersonic flow conditions and angles of attack in the range -9° ≤ α ≤15°.
Ø The measurements were based on the oil film-, color schlieren-, vapor screen-, and liquid crystal display technique, while in the numerical investigation the three-dimensional Navier-Stokes equations have been solved.
Ø Besides the leading edges intricate flow phenomena such as shock-shock- and shock-vortex-interactions could be detected on the leeward side.
Ø At α ≥ 8° the EOS flow field is characterized by a strong vortex above the wing, which is constrained by the fuselage and the wing tip.
Ø As far as the comparison of the experimental and numerical findings is concerned a good qualitative agreement has been obtained.
Conclusion
Outlook
Ø Qualitative flow visualization using schlieren and differential interferometry techniques can be carried out perfectly in wind tunnel, a quantitative utilization for density and temperature should be done as the future technical development.
Ø For the heat transfer measurement could be used the infra red photography instead of the liquid crystal display technique to simplify the experimental setup and develop the new technique of infra red photography.
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