Thanks! It's the Knight's theme from Monty Python and the Holy Grail. A lot of complaints about the background music....so I stopped using it. Have a great day!
I liked the video very much but I wish there was no background music. It is very annoying. Sometimes I could not focus on the subject but the voice of the narrator was strong and helpful to back to subject. Thanks
Great explanation Subscribed. I just have a small doubt in the concept of including velocity head in the calculation of NPSHa . If velocity head is included while calculating NPSHa then doesn't it in increase that NPSHa . But somehow it feels counterintuitive to me. I thought cavitation occurs when static pressure head becomes below vapor pressure even though the the fluid may still have velocity. But according to the correct definition like you said , cavitation will not happen even if static pressure head becomes equal to vapor pressure due to the net positive effect of inclusion of the velocity head . Is that correct ? So that means cavitation will start to happen when velocity head also becomes zero ?
Hi Dan, You are not alone in your line of thoughts, it is logical. This is why some textbooks and even some handbooks have it incorrect. Including the velocity head with NPSHa is correct. I'll give you another way to think about it. I hope it helps but my experience with many of my students is that including the velocity head in NPSHa remains counterintuitive. The manufacturer is concerned with cavitation INSIDE the pump (internals), where higher velocities are achieved due to the spinning impeller (rpm, impeller diameter, etc.). The peak internal velocity is (somewhat) independent to the velocity head at the pump suction (this is a simplification but if you consider the no slip boundary condition at the tip of the pump impeller it is reasonable). A higher velocity head at the pump suction means less conversion from static pressure head to velocity head in the internals of the pump (to achieve the nearly identical internal liquid velocity). This is why the velocity head is included in the NPSHa calculation. Thanks for your feedback and I hope this comment helps!
