Physics of Aircraft Icing: A Predictive Challenge

Transcription

1 Physics of Aircraft Icing: A Predictive Challenge Cameron Tropea Institute for Fluid Mechanics and Aerodynamics (SLA), Technische Universität Darmstadt, Germany MUSAF III ONERA, CERFACS September Toulouse TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 1

2 Thanks PD Dr. Ilia V Roisman Prof. Suad Jakirlic Dr.-Ing. Antonio Criscione Dr.-Ing. Hai Li Dipl.-Ing. Daniel Kintea Dipl.-Ing. Tobias Hauk Dipl.-Ing. Markus Schremb TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 2

3 Aircraft Icing - Overview Airframe Icing Engine Icing TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 3

4 Aircraft Icing Cause and Effect Airframe Icing Engine Icing Supercooled liquid droplets at low altitude (100µm-2mm, -3 to -10 C) Ice accretion on lifting surfaces and instruments Loss of lift and increased drag, false measurements High altitude ice crystals (50µm-500µm, <-20 C) Ice in turbine intake components and instruments Power loss, turbine damage, false measurements TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 4

5 Aircraft Icing - Physics Airframe Icing Engine Icing Drop trajectory and capture efficiency Drop impact and solidification (nucleation) under shear flow Ice accretion model Prediction of lift and drag with new geometry Ice crystal trajectory (nonspherical) and capture efficiency Ice crystal melting in intake Ice crystal impact model, with liquid film Accretion model Thermodynamic interaction with warm surfaces (blades) TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 5

6 Aircraft Icing - Physics Airframe Icing Engine Icing Drop trajectory and capture efficiency Drop impact and solidification (nucleation) under shear flow Ice accretion model Prediction of lift and drag with new geometry TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 6

7 Parameters affecting drop deposition Impact parameters Drop size Impact velocity Impact inclination Material properties, depending on the temperature Area potentially covered by ice and> movement Thermodynamic parameters Drop temperature Surface temperature Surface s thermal properties Surface topography Freezing delay supercooling) Freezing delay Time of solidification Area finally covered by ice TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 7

8 Consequences of the Freezing Delay Freezing delay Shape/area of deposited ice Position of ice deposition cold wing cold wing 0 C 0 C TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 8

9 Physics Involved Drop impact spreading, receding Contact line dynamics and wetting/dewetting Drag force imposed on deformed droplet Change of material properties Nucleation sites Solidification The challenge is to capture the physics in simplied models which can then be used for simulation purposes. TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 9

10 Impact onto Warm and Cold Surfaces 17 C Summary of Experiment Identical impact parameters Drop spreading similar Cold surface leads to increased 17 C viscosity and decreased contact angle slower receding No freezing although wall at TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 10

11 Freezing Delay Splat (30 ms) Splat/Rivulet transition (73 ms) Rivulet (130 ms) Sessile droplets (670 ms) TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 11

12 Freezing after Impact Freezing delay after impact [ms] Occurence [%] Resulting shape (2 s after impact) Frozen splat Splat/rivulet transition Frozen rivulet Liquid and frozen drops Remaining 33 % stay liquid for whole period of observation TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 12

13 Freezing Rate Highest freezing rate directly after impact Constant freezing rate after receding Freezing rate proportional to number of liquid droplets ~ ln ~ Fluid motion and large contact area enhance freezing rate TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 13

14 Freezing Rate Only small increase due to freezing delay Typical temperature for combination of fluid and substrate temperature TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 14

15 Multiple Nucleation Sites Nucleation model is missing! Schremb M, Roisman IV, Tropea C (2015) Different outcomes after inclined impacts of water drops on a cooled surface, ICLASS, Tainan, Taiwan, August TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 15

16 Contact Line Dynamics Water, air d 0 =2mm θ eq =90 Feed flow Contact angle hysteresis Kistler model TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 16

17 Contact Line Dynamics Robin Boundary Condition Linder N, Criscione A, Roisman IV, Marschall H, Tropea C (2015) 3D computation of an incipient motion of a sessile drop on a rigid surface with contact angle hysteresis. Theor. Comput. Fluid Dyn. DOI /s TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 17

18 Contact Line Dynamics Continuous Surface Force Model fσ = σκ α r κ = n α κ = α Improvements Finer mesh Better curvature TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 18

19 Crystallization of a sessile supercooled water droplet 0 ms 8 ms 16 ms 32 ms Average velocity of freezing front 1 st stage T D = K m/s T s = K 0 s 6 s 13 s 20 s 2 nd stage T D = K 1 mm m/s T s = K [S. Jung, M. K. Tiwari, N. V. Doan, D. Poulikakos. Mechanism of supercooled droplet freezing on surfaces, Nature Communications, 2012] TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 19

20 1 st stage of crystallization sketch T D = K model growing needles bumps smooth front T s = K CFD sinusoidal perturbed interface TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 20

21 From Stable Freezing to Dendrite Growth Theory Stefan Problem Mullins-Sekerka Instability Theory Mullins-Sekerka Instability Theory Marginal Stability Theory (MST) TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 21

22 Growth of Dendrites TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 22

23 Ice crystal growth Dimensionless growth, V=v t d 0 /2D, as a function of dimensionless supercooling, = T/(L/c p ) for ice crystals freely growing from supercooled pure water. v t : tip velocity d 0 : capillary length ( d 0 = σ c p T m / L 2 ) D : thermal diffusivity natural convection Kineticslimited growth Diffusion-driven growth 0.06 < T < 14.5 C [A.A. Shibkov, M.A. Zheltov, A.A. Korolev, A.A. Kazakov, A.A. Leonov. Crossover from diffusion-limited to kinetics-limited growth of ice crystals, Journal of Crystal Growth 285 (2005) ] TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 23

24 Free dendritic growth: kinetic effects Empirical model of kinetic coefficient: T T T T = T T ν T kin σ κ = Lρ v T m T v ν n, where T kin = v = n v k n kin v v n,mst n,exp k kin v v n v ( vn 1) κσ Tm n Lρ π v ( vn ) =, MST Tkin = * 2 11 kkin k kin v n v * k kin = 1 2 2π TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 24

25 Free dendritic growth: kinetic effects Empirical model of kinetic coefficient: T T = T T ν T kin σ κ = Lρ v T m T kin = v k n kin T kin = v ( v ) n * kin k 1 3 Criscione A, Kintea D, Tukovic, Z, Jakirlic S, Roisman IV, Tropea C (2013) Crystallization of supercooled water: A level-set-based modeling of the dendrite tip velocity. Int J Heat and Mass Trans. 66: TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 25

26 2 nd Stage of Crystallization Tm T D = K sketch substrate model Tm T s = T sub K planar freezing TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 26

27 Planar Freezing liquid CFD 1 mm T = K V D = 5 µl D = 2.12 mm 2.12 vs. mm h(t) mm 0 T s = K solid T sub = K x = y = z TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 27

28 Crystallization of a sessile supercooled water drop 1 st stage Heat diffusion problem (dendritic growth model) kinetic effects no thermal influence of neighboring dendrites model growing needles bumps smooth front SnowCrystals.com Dendrites grows until supercooling is exhausted 2 nd stage Heat diffusion problem (planar solidification model) Solidification of residual water between dendrite due to cooling from substrate Additional velocity due to density jump between liquid and solid (~3% of interfacial velocity ) v v n model substrate T D = Tm K Tm T sub planar freezing TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 28

29 Sessile Droplet freezing Freezing of sessile droplet in quasi 2D Supercooled water in Hele-Shaw cell with 1 mm copper spacer Triggering for smaller supercoolings ( instable envelope single dendrites) Freezing at large supercoolings ( stable envelope) TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 29 29

30 Sessile Droplet freezing Freezing of sessile droplet in quasi 2D Sessile droplet freely freezing Sessile droplet freezing in cell Aluminum bottom Copper bottom TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 30 30

31 Sessile Droplet Freezing Normal Front Velocity Freezing starts at bottom Wall contact enhances freezing velocity Front velocity equals single dendrite s velocity No influence from neighbouring dendrites TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 31 31

32 Aircraft Icing - Physics Engine Icing Ice crystal trajectory (nonspherical) and capture efficiency Ice crystal melting in intake Ice crystal impact model, with liquid film Accretion model Thermodynamic interaction with warm surfaces (blades) TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 32

33 Engine Icing Impact on a solid wall Source: Mason Engine Power Loss in Ice Crystal Conditions - Aero Quarterly QTR_04 07 Impact on a liquid film Ice accretion on a warm surface Melting TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 33

34 Accretion due to Water Droplets / Film on Surface Cold surface T surface = -8 C T flow = -8 C T ice = -8 C Surface Temperature ( C) Time (s) 1 mm -10 Warm surface T surface,0 7 C T flow = -10 C T ice = -10 C Surface Temperature Time (s) Significant influence of small water film / water droplets on ice accretion (here: generated due to warm surface) TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 34

35 Icing Mechanisms Not enough water to make the crystals stick to the surface Supercooled Ice particle droplet Not enough ice to cool the wall Ice particle 0.1 Cold wall 0.25 LWC From: [1] Currie, T.C., Fuleki, D., Knezevici, D.C., MacLeod, J.D.: Altitude Scaling of Ice Crystal Accretion, 5th AIAA Atmospheric and Space Environments Conference, San Diego, USA, TWC Hot wall TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 35

36 Aircraft Icing - Physics Airframe Icing Engine Icing Drop trajectory and capture efficiency Drop impact and solidification (nucleation) under shear flow Ice accretion model Prediction of lift and drag with new geometry Ice crystal trajectory (nonspherical) and capture efficiency Ice crystal melting in intake Ice crystal impact model, with liquid film Accretion model Thermodynamic interaction with warm surfaces (blades) TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 36

37 Ice Crystal Melting in Engine Intake Melting of non-spherical particles Experimental investigation Theoretical modeling Numerical implementation Results TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 37

38 Experimental setup Top view Side view Measurement of - melting times, - shape evolution. At various - temperatures, - humidities, - flow velocities. TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 38

39 Typical results D max Ød TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 39

40 Experimental Details Melting process at low RH Significant influence of mass transfer on particle mass RH = 4 % T = 20 C v = 1.25 m/s Extrapolation of initial mass based on the d 2 -law (area change rate is constant for evaporating droplet) Initial projected area Final projected area, Post-melting change rate TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 40

41 Theoretical modeling Major assumptions: Particle is isothermal throughout the melting process, Particle is spheroidal before the onset of melting, Heat transfer coefficient of a volume equivalent sphere is used, Heat flux is evenly spread over the ice surface, Liquid water accumulates in the mid-section of the particle. TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 41

42 Melting stages I) Warming of ice up to 0 C II) Melting with water accumulation in particle mid-section Duration of stages depends on elongation of the particle. III) Melting of ice which is completely surrounded by non-spherical droplet, Water is pinned at the edges IV) Melting of ice residual which is entirely immersed in a spherical droplet V) Warming of liquid above 0 C TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 42

43 Dimensions of spheroidal particle D max D max 2b Ød => V P => b E = D max / (2b) Spheroid has The same max. dimension and the same volume. TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 43

44 Numerical treatment Heat flux at interface to air: Melting velocity: Smoothing of irregularities Change of Level-Set field: Formation of cusps TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 44

45 Exemplary case I Stage I Stage II Stage III Stage IV Stage V TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 45

46 Comparison with experiments Very good agreement with experimental data % 9.4 % Hollow: Sphere model Filled: Spheroid model Deviation between models depends on particle aspect ratio E. TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 46

47 Comparison between models Deviation between models depends on particle aspect ratio E and initial particle temperature T 0. TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 47

48 Conclusions Experimental study has been performed Observation of shape evolution, Measurement of melting times, Observation of typical phenomena (formation of cusps, liquid collection at mid section of particle, smoothing of irregularities). A theoretical model has been developed Describes shape change, Predicts melting time with significantly higher accuracy than 1D sphere model, Formation of cusps is explained, Significant deviation of water content throughout melting in comparison with sphere model. TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 48

49 Aircraft Icing - Physics Airframe Icing Engine Icing Drop trajectory and capture efficiency Drop impact and solidification (nucleation) under shear flow Ice accretion model Prediction of lift and drag with new geometry Ice crystal trajectory (nonspherical) and capture efficiency Ice crystal melting in intake Ice crystal impact model, with liquid film Accretion model Thermodynamic interaction with warm surfaces (blades) TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 49

50 Ice Crystal Deposition Particle velocity Particle size Particle density Contact angle Impact angle Surface tension Bouncing Liquid density Liquid viscosity Film thickness TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 50

51 Numerical Approach Volume-of-Fluid method Particle poses a boundary of the domain => Mesh motion Flow is considered incompressible Navier-Stokes equation D D 1 Δ Continuity equation 0 TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 51

52 Numerical Approach air F F d water CL Contact line force: d d TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 52

53 Oblique Impacts Case II-i: Experiments: Top view Side view Numerics: TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 53

54 Maximum Penetration Depth Hydrophobic We = 50 At low We, viscosities play no role f We, /, ~ We Also applies for inclined impact! TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 54

55 Summary Particle velocity Particle size Particle density Contact angle Impact angle We / Surface tension Bouncing Liquid density Liquid viscosity Film thickness TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 55

56 Aircraft Icing - Physics Airframe Icing Engine Icing Drop trajectory and capture efficiency Drop impact and solidification (nucleation) under shear flow Ice accretion model Prediction of lift and drag with new geometry Ice crystal trajectory (nonspherical) and capture efficiency Ice crystal melting in intake Ice crystal impact model, with liquid film Accretion model Thermodynamic interaction with warm surfaces (blades) TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 56

57 Ice crystal accretion: physical model Energy equation: ( ρc T ) t P + ( ρc Tu) = ( k T ) P v ρ: Density c P : Specific heat at const. pressure T: Temperature t: Time : Velocity k: Thermal conductivity TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 57

58 Numerical approach Melting/Solidifying Enthalpy formulation Solve for temperature h [ cp, STm + cp, L( T Tm )] α LL 12 3 = α ScP, ST + α L H 2O LS Sensible heat of ice Sensible heat of liquid water Latent heat of water α S = h h H 2O I γ hi hii 0 γ + γ h I h h H 2O h H 2O < H 2O > h h I II h II T h I h II h γ: Water Content h I h II 100 % solid at T m 100 % liquid at T m TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 58

59 Numerical approach Convection Convection, Evaporation, Sublimation Crystals are assumed to be spherical. have a diameter from 90 µm up to 200 µm. be randomly distributed. TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 59

60 Numerical approach altered equation ( ρc T ) t P + ( ρc Tu) = ( k T ) P v ( ρcpt ) t ( k T ) = α ρ LLS 443 L L t LS MELTING / SOLIDIFYING α L α S + LLLG S LSG t ρ + + LG t ρ sgn SG CONDENSATI EVAPORATION / ON Heat/mass transfer coefficient SUBLIMATION / RE SUBLIMATION ( α A ) q& C Enthalpy formulation TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 60

61 Simulation of ice accretions Run 573, 543 and T wb T m [2] [2]: Currie, T.C., Struk, P.M., Tsao, J.-C., Fuleki, D., Knezevici, D.C. Fundamental Study of Mixed-Phase Icing with Application to Ice Crystal Accretion in Aircraft Jet Engines, 4th AIAA Atmospheric and Space Environments Conference, New Orleans, USA, TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 61

62 Simulation of run Regular shedding Development of the water film in proximity of the substrate - Ice is not shown Forming of a liquid layer After approx. 60 s the ice is entirely separated from the wall Shedding of the ice Substrate TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 62

63 Simulation of run Regular shedding TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 63

64 Simulation of run Well-adhered Animation Development of the water film in proximity of the substrate for the last growth cycle 10 s Liquid layer freezes during the first 10 s Afterwards it becomes stationary Result: well adhered ice layer Substrate TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 64

65 Influence of the liquid water content Run 574 2, varying LWC/TWC 0.25 Transition No transition 0.25 LWC TWC Utilization of this transition as a measure for the occurence of severe icing TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 65

66 Icing limits / 0 ICING / 0.2 Experiments from: [1] Currie et al: Altitude Scaling of Ice Crystal Accretion, 5th AIAA Atmospheric and Space Environments Conference, San Diego, USA, / 0 [2] Currie et al.: Fundamental Study of Mixed-Phase Icing with Application to Ice Crystal Accretion in Aircraft Jet Engines, 4th AIAA Atmospheric and Space Environments Conference, New Orleans, USA, [3] Struk et al.: Fundamental Ice Crystal Accretion Physics Studies, International Conference on Aircraft and Engine Icing and Ground Deicing, Chicago, USA, Assumingη eff = 0.1 and using the injected values. / 0.4 TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 66

67 Detailed Numerical Simulation + (relatively) high accuracy - High CPU cost Quasi two-dimensional model - practical - approximate - requires layer modeling TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 67

68 Theoretical Modelling x Water Ice Substrate Dimensional analysis: TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 68

69 Theoretical Modelling Phase fraction Density Heat capacity Temperature Time Rate of heat extinction Thermal conductivity Radius Imbibition velocity Latent heat of fusion Quasi-diffusion coefficient TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 69

70 Wedge Airfoil Spalart-Allmaras turbulence model y+ < 0.5 TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 70

71 Well-adhered Accretion C Run No. 553 [2] T wb [ C ] T 0 [ C ] TWC [g/ m³] MR m [-] p 0 [kpa ] 44.8 Ma [-] AOA [ ] 0 TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 71

72 Regular-Shedding Accretion Run No. 573 [2] T wb [ C ] T 0 [ C ] TWC [g/ m³] MR m [-] p 0 [kpa ] 44.8 Ma [-] AOA [ ] -6 Pressure side Suction side TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 72

73 Predictive Challenges in Aircraft Icing - Summary Airframe Icing Engine Icing Rich physics! Experimental observations have been instrumental in understanding the physics Modelling physical processes is essential for simulations Many challenges are left TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 73

74 Aircraft Icing - Physics Airframe Icing Engine Icing Drop trajectory and capture efficiency Drop impact and solidification (nucleation) under shear flow Ice accretion model Prediction of lift and drag with new geometry Ice crystal trajectory (nonspherical) and capture efficiency Ice crystal melting in intake Ice crystal impact model, with liquid film Accretion model Thermodynamic interaction with warm surfaces (blades) TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 74

75 Thanks Journal Papers Hauk, T., Bonaccurso, E., Roisman, I. V., & Tropea, C. (2015). Ice crystal impact onto a dry solid wall. Particle fragmentation. Proc. R. Soc. A 471, Kintea, D. M., Hauk, T., Roisman, I. V., & Tropea, C. (2015). Shape evolution of a melting nonspherical particle. Physical Review E, 92(3), Roisman, I. V., & Tropea, C. (2015). Impact of a crushing ice particle onto a dry solid wall. Proc. R. Soc. A 471, Kintea, D. M., Roisman, I. V., & Tropea, C. (2016). Transport processes in a wet granular ice layer: Model for ice accretion and shedding. International Journal of Heat and Mass Transfer, 97, Kintea, D. M., Breitenbach, J., Gurumurthy, V. T., Roisman, I. V., & Tropea, C. (2016). On the influence of surface tension during the impact of particles on a liquid-gaseous interface. Physics of Fluids, 28(1), Dissertations Hauk, T. (2016). Investigation of the Impact and Melting Process of Ice Particles. PhD Thesis, TU Darmstadt, Darmstadt. Kintea, D. M. (2016). Hydrodynamics and Thermodynamics of Ice Particle Accretion. PhD Thesis, TU Darmstadt, Darmstadt. TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 75

76 Thanks TU Darmstadt Institute of Fluid Mechanics and Aerodynamics Prof. Dr.-Ing. C. Tropea 76