THERMOFLUID MHD for ITER TBM. CURRENT STATUS By UCLA Thermofluid MHD GROUP Presented by Sergey Smolentsev US ITER TBM Meeting UCLA May 10-11, 2006

Presentation layout MHD and Heat Transfer in the H-H phase Electromagnetic coupling in poloidal ducts PbLi manifold experiment Buoyancy effects modeling 2-D MHD turbulence modeling Near-future plans

MHD and Heat Transfer in H-H PbLi enters the module at 470  C He enters the module at 300  C Only surface heat flux U=10 cm/s Steady state “Low conductivity grade” SiC/SiC (  =1-50, k=1-5) Issues addressed:  Heat exchange between He and PbLi  Effect of FCI ( , k) and flow regime on heat transfer  Heat leakage into He   T across the FCI

MHD calculations  =1  =5  =50 (lam)  =50 (turb) Fully developed flow model Only one channel (front row, middle) is considered Parametric analysis,  FCI =1-50 S/m Laminar flow (  =1; 5; 50) Turbulent flow (  =50) MHD velocity profiles at B=4 T

Heat transfer calculations Velocity profile from the MHD calculations Temperature and h in the He flows from the He analysis Parametric calculations of the 3- D temperature field, using k and  as parameters Typical temperature field in H-H in the poloidal flow at U=10 cm/s

Heat exchange between He and PbLi 1.Calculate temperature field in He, assuming only surface heat flux 2.Calculate temperature in PbLi 3.Calculate heat losses from PbLi into He 4.Repeat temperature calculations in He taking into account heat losses from PbLi 5.Go to step 2 Iterate until no changes occur

Heat exchange between He and PbLi Iteration 1: no heat leakage assumed Iteration 2: First wall: Mw/m 2 Divider plate: Top plate: Bottom plate: Grid plates: Side walls: Iteration 3: to be performed Tbulk at  =5 S/m, k=5 W/m-K

Temperature drop across FCI Front FCI:  SiC =5 S/m, k SiC =5 W/m-K Toroidal distance, m  S/m k W/m-K  T FCI K (t)595 Max  T FCI < 120 K No effect of  (laminar)

Heat leakage into He  S/m k W/m-K q Front MW/m 2 q Back MW/m 2 q Side MW/m (t) No effect of  (laminar) Turbulence is important  T PbLi ~(10-40) K k=1,  =1; 5;50 k=5,  =1; 5;50 k=5,  =50 (turb)

Conclusions on heat transfer. Discussion issues. Iterative procedure coupling heat transfer in He and PbLi has been established Thermofluid MHD analysis has been performed in H-H assuming “low conductivity grade” SiC/SiC Turbulence is important  What SiC/SiC we are looking for and what SiC/SiC will be achievable in the neat future?  What to do next? (D-T, comparison with DEMO, unsteady conditions, more emphasis on MHD turbulence and buoyancy effects, meaningful experiments)

Electromagnetic coupling Goal: near uniform flow distribution Flows are electromagnetically coupled How changes in one flow will affect other flows? Planning: Modeling for (1-2),(1-2-3), (2-5) in normal and abnormal conditions No ! Yes

Manifold experiment The test-article models “real” flow in the TBM, including the inlet and outlet section and three poloidal channels (Exp. A) Non-conducting and (Exp. B) conducting test-article Measurements:  P i, Q i, , V Q1: Is the flow distributed uniformly? Q2: Do we need FCI in the inlet and outlet sections? (Exp. C) Manifold optimization Status: pre-fabrication Goal: Manifold design that provides uniform flow distribution and minimizes the MHD pressure drop

Modeling buoyancy effects Significant effect on heat transfer MHD: transition to 2-D; reduction of circulation flow High Ha, high Gr. Computations are very time consuming Using periodic BC and FFT reduces the computational time by a few orders (compared to a relaxation technique) Status: testing DEMO: Ha=14,900 Gr=2.5  ITER: Ha=6350 Gr=1.5  10 9 Before using FFT: Ha= , Gr=10 7 B Goal:  2 to 5 orders in Gr  1 order in Ha

Modeling 2-D MHD turbulence Significant effect on heat transfer 0-equation turbulence model is used (my be inaccurate) Implementation of 2- equation model is in progress

Near-future plans Readdress MHD/heat transfer in DEMO, looking at similarities and differences with ITER Perform MHD/heat transfer analysis in DT Iterate with others (He, SiC/SiC, design, stress) to narrow the uncertainties Keep working on modeling (electromagnetic coupling, buoyancy effects, 2-D MHD turbulence) Keep working on the manifold experiment