Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 1 Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas THERMAL MODEL UPDATING AND ANALYSIS RESULTS PM# April 2006

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 2 INTRODUCTION  Thermal analysis has been performed on the Antenna configuration as it was at ALMA Kick-Off meeting  Main objectives were:  To debug and validate the analysis flow checking the tools used for exchanging temperature maps for thermal distortion analysis  To support the successful completion of the Design Concept definition phase

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 3 SUMMARY  A set of analysis results for the whole antenna has been generated by Alcatel Alenia Space Italia, in the frame of the Antenna re-design, as input for the execution of the thermal distortion analysis.  The following activities have been done by AASI:  Updating of the Geometrical Mathematical Model (GMM) and the Thermal Mathematical Model (TMM)  The thermal analysis for significant load cases covering the operational scenario and generation of the temperatures maps for the thermal distortion analysis

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 4 Thermal Modelling Activity  GMM  The GMM of the Antenna has been updated in the following areas by using THERMICA S/W on the basis of the re-design activities (relevant geometrical data taken from 3D PROENGINEER CAD model): Antenna Base Electrical Distribution and Switchboard Control Cabinet Electrical Cabinet for Nutator UPS Cabinet Battery Box HVAC Main Unit Outdoor Cryogenic Compressor Elevation Drive

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 5 Thermo-Optical properties  All the external surfaces are white painted except the sub-reflector and the Antenna reflector panels.  The antenna sub-reflector surface is anodized aluminium (Alodine 1200 in accordance to MIL-C class 1A).  The external skin of the reflecting panels is electroformed nickel coated with a rhodium film. Aiming at minimizing its specularity, the surface is engraved in order to have the necessary reflectivity and enable the direct observation of the sun. ITEMSolar Absorbivity  Infrared Emissivity  Antenna Reflector Antenna Sub-Reflector Other External Surfaces (Yoke, BUS, Cabin, Base)

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 6 Thermal Modelling Activity  GMM (Cont’d) ALMA OVERALL GEOMETRICAL MODEL

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 7 Thermal Modelling Activity  GMM (Cont’d) BASE External Skin Nodal Breakdown (Internal skin numbering = External Skin + 500)

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 8 Thermal Modelling Activity  GMM (Cont’d) BASE and Cylinder Thermal Protection Nodal Breakdown

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 9 Thermal Modelling Activity  GMM (Cont’d) Yoke Base Nodal Breakdown

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 10 Thermal Modelling Activity  GMM (Cont’d) Yoke Nodal Breakdown (Overall View)

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 11 Thermal Modelling Activity  GMM (Cont’d) Yoke Arms Nodal Breakdown

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 12 Thermal Modelling Activity  GMM (Cont’d) Brakes Nodal Breakdown (numbering scheme: Brake –Y nodes  Brake +Y nodes ) View +X -YView -X +Y

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 13 Thermal Modelling Activity  GMM (Cont’d) Cabin External Nodal Breakdown (internal node numbering scheme: external nodes + 9)

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 14 Thermal Modelling Activity  GMM (Cont’d) BUS Nodal Breakdown

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 15 Thermal Modelling Activity  GMM (Cont’d) BUS Nodal Breakdown

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 16 Thermal Modelling Activity  GMM (Cont’d) Reflector Nodal Breakdown

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 17 Thermal Modelling Activity  GMM (Cont’d) Legs Nodal Breakdown Leg 1/2 Leg 7/8 Leg 5/6 Leg 3/4 Legs 1/2 and 3/4 Legs 5/6 and 7/8

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 18 Thermal Modelling Activity  GMM (Cont’d) Apex and Subreflector Nodal Breakdown Subreflector Apex

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 19 Thermal Modelling Activity  Thermal Mathematical Model  The TMM of the Antenna has been updated by using ESATAN S/W in the following steps: Introduction of the linear conductors network, the radiative network and the thermal loads generated by THERMICA. Introduction of the routine to properly simulate the radiative exchange in the terrestrial environment (including contribution from water vapour radiation emission) Accounting of the convective exchange with atmosphere through the heat transfer coefficients provided by the CFD analysis for the considered wind condition

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 20 Thermal Modelling Activity  Analysis Cases  Thermal Analysis campaign is aimed at supporting the Antenna redesign activities and providing input thermal loads in the frame of the thermal-distortion analysis.  Eight nominal and one sensitivity analysis cases have been identified which are suitable to meet both the above scopes.  Thermal analysis output temperatures are available for the structural finite elements model through a specific procedure for mapping the thermal node temperatures into the structural model.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 21 Analysis Cases Summary

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 22  Case 1 provides the maximum temperatures on the Antenna and, consequently, the maximum absolute temperature differences with respect to the temperature of the antenna during its integration. It is the absolute hot case; maximum temperature values are reached on the reflecting panels, whereas the other components are in the shadow of the Reflector  Case 2 provides the minimum temperatures on the Antenna and, consequently, the maximum absolute temperature differences with respect to the temperature of the antenna during its integration  Cases 3, 4 and 5 provide the maximum temperature gradients on the structure along the three co- ordinate axes  Case 6 represents a critical hot case for BUS, Cabin, Yoke and Base  Case 7 provides the maximum absolute temperature differences with respect to the integration temperature of the antenna (like Case 1), but with the sun that partially illuminates the Reflector panels to have the maximum gradient on the Antenna Reflector  Case 8 provides the maximum temperature gradient on the Antenna Reflector and between Reflector and BUS, having the sun that partially illuminates the Reflector panels and the cold wind on the BUS  Case 9 provides sensitivity to the thermo-optical properties of the Antenna Reflector panels with respect to the identified worst hot case (case 1). Analysis Cases Description

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 23 Analysis Results  Summary of min/max temperatures of the Antenna main areas and maximum solar flux absorbed in the secondary focal region:  The maximum absorbed flux of 0.05 W/cm2 is obtained in the Case 1 (worst hot case 1)  The design is compliant to the requirement (<0.3 W/cm2)

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 24 Analysis Case 1 - Temperature Maps

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 25 Analysis Case 2 - Temperature Maps

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 26 Analysis Case 3 - Temperature Maps

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 27 Analysis Case 4 - Temperature Maps

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 28 Analysis Case 5 - Temperature Maps

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 29 Analysis Case 6 - Temperature Maps

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 30 Sensitivity to Reflector Panels Thermo-Optical Properties (Case 9)  Passing from an  /  ratio of 4 (nominal cases with rhodium film on the reflector panels) to about 8.4 (corresponding to rhodium film removal  Case 9), the absorbed solar flux is retained in the system and the temperature of the antenna reflector could reach the peak of 170°C in the area around the focal plane (namely in the zone with the lower view factor toward the environmental sinks). Absorpitivity α Infrared Emissivity Є α/Єnotes Nominal value Rhodium film over nickel panel Rhodium film removed (Case 9) t/o properties of nickel panel

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 31 Conclusions  Debugging and validation of the analysis flow has been completed.  Tool used to exchange temperature maps for thermal distortion analysis has been successfully verified  No criticalities in the antenna temperatures are shown by the current analyses  Final verification is to be done by thermal-distortion analysis and error budget, considering also analysis cases 7 and 8 that introduce a high thermal gradient on Antenna Reflector, Bus and Cabin.  As shown by sensitivity analysis (Case 9), thermo-optical properties of rhodium film applied over the reflector panels would avoid high panel temperatures in the extreme worst hot case 1 (hot conditions, no wind, Antenna pointed directly to the Sun).  The final Antenna design will be extensively analysed in order to verify and demonstrate that all the requirements are met.