RF-Accelerating Structure: Cooling Circuit Modeling Riku Raatikainen 16.8.2010.
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Transcript of RF-Accelerating Structure: Cooling Circuit Modeling Riku Raatikainen 16.8.2010.
Part I Improved cooling circuit modeling
- About me and my work at CERN- Introduction to improved cooling circuit modeling
- Coupled thermal-structural modeling- Used engineering data
- Improved cooling circuit model- Results for the SAS solved earlier by using CFD
(computational fluid dynamics) - Conclusion
Part II Case study: Test Lab Module
- Introduction- Results- Conclusion
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Content
• Summer trainee of HIP (3 months)
• Student in Master’s Degree Programme of Mechanical Engineering majoring in Applied Mechanics
• Main task and motivation
- Improved cooling circuit modeling for TMM accelerating structures- The aim was to gain more efficient modeling method in order to solve current and future coupled thermal-structural models.
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
General
• Coupling CFD and structural analysis problems usually leads to complicated and computationally quite heavy models
•This is due to coupling of the equations of continuum mechanics and fluid dynamics which especially in 3D cases occur to be very complex
• The improved cooling modeling that is to be presented here reduces this 3D fluid flow into 1D flow which is still capable of acting in a 3D environment
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Introduction to improved cooling circuit modeling
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
First test models
Implementation to SAS cooling and comparing the efficiency to the model done by using 3D CFD
Applying the method to up- to- date model
Process
Methodology
• Problem was solved by using 1D Thermal Fluid elements (FLUID 116) which have both temperature and pressure degree of freedom
• The element has a ability to conduct heat and transmit fluid between its two primary nodes
• The solid copper body was connected to the fluid elements via convection surface elements
• If the pressure is a degree of freedom the element is always nonlinear
! Convec is named component of nodes on convection surfaces. ! Piping is the named component of fluid elements ! NDSURF - Generates surface elements and connects them to the fluids
ndsur f,'Convec','Piping', 3 ! Surface elements in 3D environment
! Specification of mass flows - Note direction lines
cmsel, s, Piping sfe, all,, hflux,,0.01922 ! Mass flow definition
esel, s, type,,5000 sfe, all,, conv,, 3737 ! Heat transfer coefficient
alls fini
/solu
*******************************************Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Methods
Fluid elements connected to the copper body via
surface elements (APDL)
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Structural Thermal
Young's Modulus
(Pa)
Poisson's Ratio Density
(kg/m^3)
Thermal Expansion
(1/°C)
Thermal Conductivity
(W/m·°C)Specific Heat
(J/kg·°C)
Copper Alloy 110E9 0.34 8300 1.80E-05 401 385
Water 1000 4.20E-02 0.645 4187
• The heat transfer coefficient used between the water and copper is 3737 W/m²·°C (EDMS 964717 v.1)
• The mass flow rate is 276.7/4 l/hr for one SAS (EDMS 964717 v.1)
• The error estimation for the absorbed heat by the water is done by using the heat conservation
• Unit system in (N, m, s, kg, °C)
Materials
• In this case calculations were done to one of the SAS which was analyzed earlier by using 3D CFD
• Instead of applying a 3D fluid flow directly into the cooling channel, a separate wiring model was created which transports the fluid inside the structure
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Improved cooling circuit model
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Mesh, loads & boundary conditions
simply supported
simply supported
fixed
nonlinear heat flux(EDMS 964717 v.1)
standard earth’s gravity
Beam
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Results
Temperature distribution (unloaded)
Max. 35.37 °C, ≈ 1.6 % off from heat balance
Twater in = 25 °C Twater out = 35.37 °C
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Temperature distribution (loaded)
Max. 33.49 °C, ≈ 1.6 % off from heat balance
Twater in = 25 °C Twater out = 33.49 °C
Results
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Temperature distribution in the copper body (unloaded)
Temperature distribution in the copper body (loaded)
Results
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Axial displacement (unloaded)
Axial displacement (loaded)
Maximum vertical displacement ≈ 2.8 μmunloaded -> loaded
Results
• 1D thermal fluid elements gives excellent results and they are in agreement with the previous ones
• Computational time collapsed to only a fractions compared to the results obtained by using 3D-CFD
• New and more efficient method of solving coupled thermal-structural problems was achieved.
• Moreover, the method provides an efficient tool to design optimisation
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Conclusions
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Extra
The method is already being applied to module level cooling by Risto
• The design parameters are the same as above but the diameter of the channel is now 6 mm instead of 7 mm. Hence, the flow is more turbulent.
• Both thermal and structural analysis is performed. Moreover, the pressure loss is obtained
• The geometrical model with the cooling routing is presented below
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Introduction
mass flow out
mass flow in at 25 °C environment at 30°C
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
fixed
simply supported
standard earth’s gravity
nonlinear heat flux(EDMS 964717 v.1)
Mesh, loads & boundary conditions
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Results
Temperature distribution (unloaded)
Max. 35.19 °C ≈ - 0.1% off from heat balance
Twater in = 25 °C Twater out = 35.19 °C
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Temperature distribution (loaded)
Max. 33,37 °C ≈ 0.2 % off from heat balance
Results
Twater in = 25 °C Twater out = 33.37 °C
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Temperature distribution in the copper body (unloaded)
Temperature distribution in the copper body (loaded)
Results
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Beam
Illustration of the vertical displacement field of the iris (the most critical) from unloaded to loaded case
Max ≈ 2.8 μm
Results
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
- Flow was considered to be continuous, fully developed and turbulent. Friction factor was calculated by using the implicit Colebrook-White equation for smooth pipes, f ≈ 0.037
- Element reduces the pipe into a straight pipe. Minor losses in the elbows was taken into account as a equivalent length.
Pressure loss
Total pressure drop ≈ 101,34 mbars (ansys)≈ 100,53 mbars (hand calc.)
• The 1D fluid elements are capable of working efficiently also in more complex geometries
• For more even thermal distribution, a smaller mass flow rate can be used for loaded case
• Moreover, different kinds of support boundary conditions can be used to adjust the displacement field
• Pressure loss can minimized by using larger radius tubes and bendings, if needed
Cooling Circuit Modeling, Riku Raatikainen, 16.8.2010
Conclusions