Flow Visualizations and Heat Transfer Measurements in ......A rg on -Io n ic L a se r P =10 W att F = - 3 0 m m Test Section Laser Light Sheet Shifting M irror Flow with Humidity photo

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.