Impeller Noise At Higher RPM 1800+
Impeller Noise At Higher RPM 1800+
(OP)
Ok so I have a water pump used in a computer liquid cooling solution. I am finding that the impeller whether it is in water or not makes a kind of whining noise when it hits around 1800rpm. Sometimes right around 1800 or above if you dont here the noise you can tap the fins on the impeller then the whine will start, I was wondering if anyone has had this experience, and whether or not it is a sleeve shaft tolerance issue, causing the impeller to wobble at higher rpm, or something else. The impeller has a magnet in it which is seated in a housing with a stator which spins the impeller. The fit is quite snug, but it was originally designed so a small amounts of fluid can pass down in between the sleeve and shaft to lubricate the two components. The sleeve attached to the impeller plastic is brass and the shaft is stainless steel. Thoughts?





RE: Impeller Noise At Higher RPM 1800+
RE: Impeller Noise At Higher RPM 1800+
What you describe sounds like an instability that occurs at a particular speed. It could be a resonance. That fact that you can initiate the noise by tapping on the assembly agrees with this possibility. The other possibility that occurs to me is a whirl instability in the bushing that supports the rotating assembly. This could be occurring as a result of excess clearance as a result of the dry running or inadequate lubrication suggested by my first set of questions.
Johnny Pellin
RE: Impeller Noise At Higher RPM 1800+
RE: Impeller Noise At Higher RPM 1800+
RE: Impeller Noise At Higher RPM 1800+
Mike Halloran
Pembroke Pines, FL, USA
RE: Impeller Noise At Higher RPM 1800+
Record the whine and determine the frequency. If the frequency is approximately 1/2 the rotation speed, that usually indicates a whirl problem.
If you just want the noise to go away, try graphite dust??? If you have been rubbing enough to wear the material, it might help temporarily. Don't think it will make things worse.