1. High Power Hg Target Conceptual Design Review Hg Jet Nozzle Analysis M. W. Wendel Oak Ridge National Laboratory February 7-8, 2005

2. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 2 Conceptual Design Review 7-8 Feb 05 An Initial Computational Fluid Dynamic Analysis was completed. 1 cm Hg nozzle at 20 m/s 2 1.9-cm supply lines at 2.8 m/s

3. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 3 Conceptual Design Review 7-8 Feb 05 Only the mercury itself was modeled in the simulation. Constant pressure at outlet. 21.3 kg/s inlet. Boundary conditions No-slip walls at all other boundaries.

4. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 4 Conceptual Design Review 7-8 Feb 05 The computational mesh consisted of 230,545 hexahedral control volumes.

5. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 5 Conceptual Design Review 7-8 Feb 05 The computed flow shows smooth streamlines for the inlet lines and reservoir, but extreme conditions near the nozzle inlet.

6. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 6 Conceptual Design Review 7-8 Feb 05 The computed pressures show cavitation will occur at the nozzle inlet. Computed pressure differential is 722 psi

7. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 7 Conceptual Design Review 7-8 Feb 05 The computed pressures are particularly low where the flow accelerates around the corners. NOZZLE FLOW TOP VIEW NOZZLE FLOW

8. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 8 Conceptual Design Review 7-8 Feb 05 A shorter (1/2-inch) orifice was also analyzed

9. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 9 Conceptual Design Review 7-8 Feb 05 Computed stream-lines are similar and the total pressure drop is just under 800 psi.

10. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 10 Conceptual Design Review 7-8 Feb 05 Again, cavitation is predicted, although the conditions are less severe.

11. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 11 Conceptual Design Review 7-8 Feb 05 Cavitation is highly likely because of the low pressure at the nozzle exit, and the high velocity in the nozzle.  P static = P stagnation – ½  V 2  is density  V is velocity  If P static < P sat, then mercury will cavitate  The CFD model is not conservative in predicting cavitation due to the transient aspect of the flow which is not simulated.  In the SNS Target Test Facility mitered bends, CFD results showed much less severe conditions than computed here. for 20 m/s, ½  V 2 = 400 psi for 30 m/s, ½  V 2 = 900 psi

12. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 12 Conceptual Design Review 7-8 Feb 05 Cavitation in the nozzle is undesirable.  Short nozzle lifetime  Choked flow  Erratic jet flow pattern  Noise

13. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 13 Conceptual Design Review 7-8 Feb 05 Design changes can reduce or eliminate cavitation.  Redesign the nozzle  Rounded corners  Contoured inlet  Increase the chamber pressure  Ultimately the nozzle design needs to be tested.

14. O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 14 Conceptual Design Review 7-8 Feb 05 Recommended Future Work  Analyses on improved nozzle designs  Literature searches on intake nozzle designs