1. Hydrodynamic Properties of Annular Cavitator College of Aerospace Sci. & Tech. National University of Defense Technology Changsha, CHINA Presenter: Ming-dong LIN

2. LOGO NUDT Contents 1. Backgrounds 2. Numerical Method 3. Results & Discussion 4. Conclusion CAV2012, Singapore

3. LOGO CAV2012, Singapore Backgrounds Fully Wetted  Drag ∝ V 3  Propellor  Low speed (<70Kn) Navigation styles underwater Supercavitating  Drag ∝ V 2  Rocket propulsed  Ultrahigh speed (>200Kn) Revolution NUDT

4. LOGO CAV2012, Singapore Backgrounds  Studies of supercavitating flow  Logvinovich ( IHM, Ukraine ) proposed the theorem of Independence of Caivity Section Expension, which is testified by many experiments. NUDT

5. LOGO CAV2012, Singapore Backgrounds  Studies of supercavitating flow  Kunz, Lindau, et.al ( APL, The Pennsylvania State University, US ) improved numerical method for both partial and fully developed supercavities, and coupled the flow simulation with the vehicle trajectory. NUDT

6. LOGO CAV2012, Singapore Backgrounds  Studies of supercavitating flow  Hydrodynamic properties of different cavitators were tested by Kuklinski (NUWC, US). NUDT

7. LOGO CAV2012, Singapore Backgrounds  Critical technologies of long distance supercavitating flight Supercavitating hydrodynamics Water ramjet propulsion system Advanced motion control strategy NUDT

8. LOGO CAV2012, Singapore Backgrounds  Hydrodynamic properties of annular cavitator ? Supercavity water ramjet annular cavitator with water injection of “Shkval-E” NUDT

9. LOGO Numerical Method CAV2012, Singapore NUDT A. Governing equations The continuity, momentum equations of mixture: The continuity equation of the vapor: The mixture property:

10. LOGO Numerical Method CAV2012, Singapore NUDT B. Rayleigh-Plesset cavitation model C. Standard turbulence model

11. LOGO CAV2012, Singapore Numerical Method  Vehicle model  Computational grids vehicle NUDT 2m 10cm 20cm 500,000 grids

12. LOGO CAV2012, Singapore Numerical Method  Computation setting NUDT CaseP out [MPa]D tube [cm]CaseP out [MPa]D tube [cm] 14.02.053.04.0 2 3.063.54.0 3 7 4 5.084.54.0 Table 1. Differenct CFD models and boundary conditions

13. LOGO Results & Discussions Hydrodynamic properties of annular cavitator Cavity size Pressure field Injecting flow CAV2012, Singapore NUDT Drag

14. LOGO Results & Discussions CAV2012, Singapore NUDT  Pressure field Pressure distributions on cavitator surface Stagnation ring moves outward Stagnation ring is stable

15. LOGO Results & Discussions CAV2012, Singapore NUDT  Drag CaseF cav [N]F tube [N]F total [N]Increment[%] 0306080 0 1302601565.431825.43.98 2287203408321284.97 3264805870323505.69 4234808886323665.74 5267405488322285.29 6266405676323165.58 7264805870323505.69 8262606076323365.65 Table 2. Forces acted on cavitator region Increase with tube size Increase with outlet pressure

16. LOGO Results & Discussions CAV2012, Singapore NUDT  Injecting flow Mass flow and velocities in different cases

17. LOGO Results & Discussions CAV2012, Singapore NUDT  Cavity size Decrease with tube size Increase with outlet pressure

18. LOGO Conclusions CAV2012, Singapore NUDT  Pressure distribution changes significantly on cavitator surface which results in the increase of the drag.  The injecting flow is proportional to the tube size, and decreases with the outlet pressure.  Compare with disk, the annular cavitator generates smaller cavity. The cavity size decreases with the tube size and increases with the outlet pressure.

19. College of Aerospace Science and Technology National University of Defense Technology