Posted by Bob on September 10, 1999 at 07:09:13:
In Reply to: Strange phenomenon posted by Ian Easton on September 10, 1999 at 04:28:04:
When you change a valve (or anything else) in the airstream, you experience what the physicists call 'transients'. The air flow, density, velocity, etc. are not steady at this point and cause effects like you are experiencing. Organists call them 'chifs' because on an organ they normally produce some sort of a whistle in the tone. I suspect your problem is a transient change in resistance which is more pronounced when you move the valve quickly. Once the transient dies out, your embrochure becomes stable along with the rest of the system. It is the same effect as when a gate valve on an automatic washer closes and you hear it in the plumbing all over the house.