Different phase shifts
Different phase shifts
(OP)
Hi guys,
I have been experimenting with a home made single plane balancer. I have used an accelerometer mounted on top of a ducted fan. I use two methods for determining phase shifts between trial runs,
1. A IR sensor which index's a white marker on the fan hub. This signal is superimposed onto my CRO with the acceleromter signal.
2. A strobe light which shows position of the imbalance. This strobe basically tells me the angle where the max acceleration peaks.
Now, the part that confuses me is that when I use setup (1) I get a CLOCKWISE phase shift between the no weight and trial weight runs. However, when I use setup (2) I get an ANTI-CLOCKWISE phase shift between the no weight and trial weight runs.
Why don't I get a phase shift in the same direction?
cheers
M.
I have been experimenting with a home made single plane balancer. I have used an accelerometer mounted on top of a ducted fan. I use two methods for determining phase shifts between trial runs,
1. A IR sensor which index's a white marker on the fan hub. This signal is superimposed onto my CRO with the acceleromter signal.
2. A strobe light which shows position of the imbalance. This strobe basically tells me the angle where the max acceleration peaks.
Now, the part that confuses me is that when I use setup (1) I get a CLOCKWISE phase shift between the no weight and trial weight runs. However, when I use setup (2) I get an ANTI-CLOCKWISE phase shift between the no weight and trial weight runs.
Why don't I get a phase shift in the same direction?
cheers
M.





RE: Different phase shifts
RE: Different phase shifts
I've been using your spreadsheet for my analysis (SinglePlaneBalGraphGood.xls). Its a great tool for learning. I'm finding that "lead angle" works and "lag angle" doesn't. When I run through the hand calc I'm finding that the Ucw plotted in the spreadsheet is in the opposite direction when using "lag angle". Did I get this wrong?
cheers
Mark.