Non-MHD/MHD Experiment under JUPITER-II Collaboration

Transcription

1 JUPITER-II FuY2001FuY2006 Non-MHD/MHD Experiment under JUPITER-II Collaboration (Experimental and Numerical data are removed because of unpublished data) Tomoaki Kunugi 1, Takehiko Yokomine 2, Shin-ichi Satake 3, Hiroyuki Nakaharai 2, Hidetoshi Hashizume 4, Kazuhisa Yuki 4, Akio Sagara 5 Junichi Takeuchi 6, Neil B. Morley 6, Mohamed Abdou 6 1 Kyoto University, 2 Kyushu University, 3 Tokyo University of Science, 4 Tohoku University, 4 National Institute of Fusion Science, 6 University of California, Los Angeles, Seminar on Fusion Blanket and TBMs 1 1

2 Outline 1. Background and Objectives (Introduction) 2. Overview of the experimental facility and numerical simulation 1. Pipe flow loop 2. Magnet 3. PIV 4. Heat transfer 3. Flow field measurements 1. Review of FuY Setup 3. Results 4. Heat transfer measurements 1. Review of FuY Setup 3. Results 5. Summary and Conclusions 6. Current status and Future plans 1. New perspectives for heat transfer experiment 2. New PIV measurement Seminar on Fusion Blanket and TBMs 2 2

3 6.1 Time Schedule for Six-Year Project FuY 2001 FuY 2002 FuY 2003 FuY 2004 FuY 2005 FuY 2006 Thermofluid Flow Experiments Non-magnetic Phase Magnetic Phase Facility: FLIHY-2 (UCLA) Turbulence Visualization Experiments Heat Transfer Experiments Turbulence Visualization Experiments Heat Transfer Experiments PIV and heat transfer measurements of turbulent pipe flow Same geometries as with magnetic field Integrated FLIBE Experiment? Check & Review Continue with heat transfer, or another option Check & Review Continue with MHD, or another option? Check & Review Flibe Loop, or another option? Seminar on Fusion Blanket and TBMs 3 3

4 1.1 Background and motivations (1): Why FLiBe? FLiBe based fusion reactors Liquid wall concepts (Abdou et al) FFHR concept (Sagara et al) Advanced steel (Wong et al) Characteristics of FLiBe Advantage: Negligible MHD pressure drop High temperature capability Breeding material (containing Li) Disadvantage: Toxic and corrosive to some material Narrow operating temperature window Low thermal conductivity (High Prandtl number fluid) Seminar on Fusion Blanket and TBMs 4 4

5 1.1 Background and motivations (2) Heat transfer characteristics of high Prandtl number fluid (Pr=20~40) High viscosity, low thermal conductivity Thermal boundary layer is much thinner than viscous boundary layer Heat tends to be confined to heating surface Turbulent motion plays important role Effect of Magnetic field Flow laminalization (turbulence suppression) Modification of velocity profile Deterioration of heat transfer Design issues Operating temperature window Heat transfer efficiency Seminar on Fusion Blanket and TBMs 5 5

6 1.2 Objective of the project Obtain fundamental knowledge MHD turbulent flow of low conductivity fluid Effect of MHD force on heat transfer characteristics Provide experimental evidence for numerical simulation community Contribute to fusion reactor design Providing experimental data Refining MHD turbulent heat transfer modeling Seminar on Fusion Blanket and TBMs 6 6

7 2. Overview of the flow facility KOH solution flow loop 2T electro-magnet PIV (Particle Image Velocimetry Heat transfer Seminar on Fusion Blanket and TBMs 7 7

8 2.1 Pipe flow facility (Schematic view) 1.4 m Flow rate adjustment with variable frequency controller and by-pass leg Fluid temperature is controlled by heat exchanger within 0.5 C PIV D = 89 mm, L = 7 m Acrylic pipe Heat transfer 1: D = 90 mm, L = 6.7 m 2: D = 51 mm, L = 4.0 m Stainless steel pipe (more than 70D) Seminar on Fusion Blanket and TBMs 8 8

9 2.2 Magnet Seminar on Fusion Blanket and TBMs z[cm] 0 0 z[cm] y[cm] y[cm]

10 2.3 PIV measurement CCD: 768x484pixels Laser: Nd:YAG Laser 15Hz 50mJ Interrogation window: Initial step:128x64 Final step: 16x8 (0.59x0.25mm) 50% window overlap t: 15ms (Re=5300, NW) 10ms (Re=5300) 6ms (Re=11300) Seeding particles: Diameter: 5µm Specific gravity: 1.02 Seminar on Fusion Blanket and TBMs 10 10

11 2.4 Heat transfer measurements Heaters have 9 sections Seminar on Fusion Blanket and TBMs 11 11

12 2.5 Governing equations u =0 2 u 1 2 Ha + ( u ) u= p + u+ ( j B) t Re Re 2 ϕ = ( u B ) j= ϕ + u B Re= uτδ / ν : Reynolds number Ha = δ σ / ρν : Hartmann number B 0 τ τ Seminar on Fusion Blanket and TBMs 12 12

13 2.6 DNS code Control volume method with staggered grid 3rd-order Runge-Kutta method and Crank- Nicolson method Fractional step method Pressure Poisson equation for FFT in x-z direction, TDMA in y direction. Scalar potential equation for FFT in x-z direction, TDMA in y direction. Seminar on Fusion Blanket and TBMs 13 13

14 2.7 Non-MHD/MHD Pipe Flow at Lower & Higher Reynolds number Re b Re b Grid number (zrφ) Grid number (zrφ) Computatio nal Domain (zrφ) Computatio nal Domain (zrφ) φ Spatial resolution ( z + r + r + φ) r, r, 2πr , r, r, 2πr , Spatial resolution ( z + r + r + φ) r, r, 2πr , r, r, 2πr , r, r, 2πr , Ha Ha Seminar on Fusion Blanket and TBMs 14 14

15 3.3 Review of Non-MHD Flow (Fluctuating vector fields) y (mm) x (mm) Seminar on Fusion Blanket and TBMs 15 15

16 3.4 Review of Non-MHD Flow (Summary) Mean velocity profile Accurate u+ required (Sensitive to u+) McEligot s method (Curve-fitting using van Driest s near wall turbulence model) Perfect agreement with DNS by Satake (2000) Turbulence intensity distribution Good agreement with DNS Down to y+5 for Re=5400 Down to y+=10 for Re=11000 Disagreement in near wall region Optical distortion (pipe curvature) Similar result by Westerweel(1993) Reynolds stress profile Good agreement with DNS With curvature compensation Turbulence structures Similar structures are observed in both PIV and DNS Will be published on Exp. Fluids Seminar on Fusion Blanket and TBMs 16 16

17 3.5 Experimental Setup of PIV for MHD Flow (1) Modifications of PIV system Camera (Phantom) New light-sheet optics Seminar on Fusion Blanket and TBMs 17 17

18 3.6 Experimental Setup of PIV for MHD Flow (2) Camera Laser & Controller Phantom5.0 (Vision research) 1024 x 1024 pixel Lens: TAMRON 350 mm Extention tubes are used for focusing the object 1.0 m from the lens PIV images are captured at 30 Hz Water jacket Compensate the distortion due to the pipe curvature Nd:YAG Laser (New wave) Pulse generator (Timing controller) (For synchronization) Light Sheet Optics L aser Laser Sheet Cylindrical Lens & M Mirror Light sheet optics is comprised of collimator, cylindrical lens, and mirrors. Seminar on Fusion Blanket and TBMs 18 18

19 3.9 Fluctuating vector fields (Movie) Re=5400, Ha=0 Re=5400, Ha=20 Seminar on Fusion Blanket and TBMs 19 19

20 3.12 Summary of PIV Measurement Flow field measurements were performed at Re=5400 and 11600, Ha=0, 5, 10, 15, 20. The camera view field was chosen as 90x90 mm (equivalent to whole cross section) 45x45 mm (equivalent to radius) 30x30 mm Image-processing was performed only for the case with 30x30 mm view field. Other data sets will be processed soon Intermittent will be investigated Number of frames may not be enough for statistical convergence Flow development length under the B field may not be enough Turbulence fluctuation was not completely suppressed with vanishing turbulence production Seminar on Fusion Blanket and TBMs 20 20

21 3.13 Summary Comparison of PIV and DNS Since the Reynolds numbers are slightly higher for the PIV experiments, there are some discrepancies. For Re=11600, Ha=10, mean velocity and statistics agree very well except for minor discrepancy for mean velocity. For Re=5400, Ha=20, turbulence intensities have different Further computation For better convergence, computation will be continued for Ret = 360, Ha = 10. Ret = 360, Ha = 20 will be performed after the convergence of the previous case. Heat transfer calculation will be planed for Pr = 5, Ha = 10 and 20. Change in publication schedule Submission for TSFP is canceled. Submission for ETC11 is considered for alternative. Seminar on Fusion Blanket and TBMs 21 21

22 4.2 Experimental Setup for Heat Transfer (1) Magnetic field 1400mm(15.7D) 100mm heating section 89mm dz = 305mm 100mm dz dz dz dz Thermocouple section 1720mm 3000mm Section TCs (0, 45, 90, 135, 180, 225, 270, 315 degree) Section TC tower Test section 8m long SUS pipe with inner diameter of 89mm heated uniformly by heating tape Forty T-type thermocouples with a diameter of 0.5mm are fixed with high thermal conductivity grease radial temperature distribution of the fluid flow in the pipe is measured by means of T.C.s tower (TC tower) Ice bath for cold junction Seminar on Fusion Blanket and TBMs 22 22

23 4.3 Experimental Setup for Heat Transfer (2) T.C. φ 130µm SUS plate TC tower T type T.C.s Magnetic field Magnet Flow direction TC tower TC tower consisted of inconel sheathed K-type T.C.s Diameter of T.C. is 0.13mm T.C. is arranged from the inner wall surface to the centre of the pipe The 63% response time of this thermocouple is 2ms Seminar on Fusion Blanket and TBMs 23 23

24 4.7 Discussion for the Results in FuY2005 Nusselt number Nusselt number decreases with applied B field due to the turbulence suppression Nusselt number decreases along the flow direction Hartmann flow development Mean temperature profile Resolution in the near-wall region is not sufficient Seminar on Fusion Blanket and TBMs 24 24

25 4.11 Current Status Temperature profiles were measured for Ha=0, 5, 10 Pr=5 Horizontal probe (Hartmann wall) Re=7400, 9000, 11000, 15000, Vertical probe (Parallel wall at the top) Re=7400, (3 different heat flux), Vertical probe (bottom) Re=11000 Things to be done Focus on Re=11000 Various heat flux to investigate mixed convection and thermal stratification Seminar on Fusion Blanket and TBMs 25 25

26 Connection of new test section to existing loop Tank Heater Flow direction New test section for measurement of inner temperature profile BOB Actuator Seminar on Fusion Blanket and TBMs 26 26

27 Design of new test section Micro meter Inside-view KOH flow T.C.s φ 2mm bellows Push rod (φ 5mm) 55mm Push rod guide Spring Seminar on Fusion Blanket and TBMs 27 27

28 Detail of test section T.C. No st measurement point from inner wall mm φ0.1mm T.C. is supported by φ0.16mm stainless pipe Six T.C.s array Stainless wall Seminar on Fusion Blanket and TBMs 28 28

29 Setup in BOB s gap Position for vertical B field Position for horizontal B field Position for vertical B field Seminar on Fusion Blanket and TBMs 29 29

30 Summaries of FuY06 s experiment Temperature profile with conducting wall can be measured toward low Reynolds region. Effect of B field on temperature fluctuating can be cleared. Above two results really aids in remodeling turbulent model for heat transfer. Effect of thermal stratification on heat transfer performance has been examined. Temperature profile is generated by interaction between laminarization due to B effect and thermal stratification. Temperature field cannot be treated as passive scalar in numerical simulation. Degradation of heat transfer performance due to B field is larger than conventional prediction. Seminar on Fusion Blanket and TBMs 30 30