Ventilation efficiency for Horn cooling TS/CV/DC CFD Team I was supposed to estimate the efficiency of the ventilations system of the CNGS Horn Area. Ventilation efficiency for Horn cooling Moritz Kuhn

THE PROBLEM The CNGS Project consists in producing a neutrino beam at CERN and sending it toward the Grand Sasso Laboratory in Italy. The Horn System itself is dedicated to focus the particles, which are produced in the target, in to a beam. Through the particle energy deposition, we have a heat up on the structure of the Horn System and its Shielding. The CNGS Project consists in producing a neutrino beam at CERN and sending it toward the Grand Sasso Laboratory in Italy. The Horn System itself is dedicated to focus the particles, which are produced in the target, in to a beam. Through the particle energy deposition, we have a heat up on the structure of the Horn System and its Shielding. The heat dissipation in the Horn itself will be removed by a water cooling system on the one hand. And on the other hand an air ventilation system will be installed to remove the heat from the Horn support structure and the Horn Shielding. This ventilation system will be checked in this work. From the reality I have built the CFD-Model. Moritz Kuhn

The Model - Geometry Neglect of the stairs between the single parts of the Horn Shielding, mathematical correction of the gravity Combination of the single parts of the Horn Shielding to only one body. Only the air is modelled I neglected the stairs between the single parts of the Horn Shielding, so the combination of the single parts to one body is possible. The slope is in the model not visible, but we have a mathematical correction of the gravity in the simulation. In this picture we see the solids, the Shielding of the Horn. Because ventilation means airflow, the surrounding air has to be modeled. Moritz Kuhn

The Model – Mesh, Boundaries CFD Model: Negative of the real case, with a finer mesh under the Horn Shielding. Mesh: About 1 million cells (Tetrahedral mesh type) Boundary Conditions: Heat Source on the wall of the Horn Shielding (53 kW) and on the Aluminium Frame (250 W) Airflow Inlet: 11600 m³/h Assumption of adiabatic walls for the cavern So the CFD Model is a negative of the real case, with a finer mesh under the Horn Shielding, because this is the most interesting part. It has a total amount of 1 million cells of the tetrahedral mesh type. Because the solid parts are not modeled, we set the heat source in Watts per square meters on the walls of the Horn Shielding, as one boundary condition. For the walls of the cavern we assumed adiabatic conditions. We have also an airflow at the main inlet of about 11600 m3/h. First results has shown a very poor ventilation process. From these results the decision was done by the CNGS-Project-Team to add gaps in the roof of the shielding. C L I C K !! Nevertheless after this modification there were still some critical points with high temperatures, so now two trenches will be added in the concrete floor to blow the air directly in these critical regions. C L I C K !! And C L I C K for the next slide! Morit Kuhn

Results: Temperature and Velocity Maps Moritz Kuhn The results are also temperature and velocity plots. This is a cut through the cavern in the middle of the Horn. To calculate one second real time we need 30 minutes of calculation time on four processors for a model like this. To summarize: With the CFD-tool it was possible to find solutions to improve the ventilation process under the Horn Shielding and with the following modifications it was feasible to reduce the temperature from 100 to 60 Celsius degrees. Condition in which the Aluminium Horn Support Structure will not lose its stability. Moritz Kuhn

Thanks for your attention! Any questions? TS/CV/DC CFD Group Thanks for your attention! Any questions? EDMS 49 22 10 Thanks for your attention! Any questions? EDMS: 49 22 10 Moritz Kuhn