|The paper presents results from ﬁlm thickness measurements in a bearing chamber test rig. The measurements were performed at different operating conditions and with two offtake designs. |
A discussion of the measurement technique using in-situ calibrated capacitive sensors shows good accuracy and repeatability.
The ﬁlm thickness results are ﬁrst compared to measurements with the same chamber in a vented conﬁguration. The analysis of the measurements at various operating conditions shows a strong inﬂuence of the shaft speed, the chamber pressure, and the offtake design. In contrast to that, ﬂow rate and scavenge ratio have only minor inﬂuence. Furthermore, the momentum ﬂux of the core air ﬂow is proposed as a suitable parameter with which the inﬂuence of shaft speed and pressure can be correlated to the ﬁlm thickness distribution.