Axial Spacing Effects on Rotor-Rotor Interaction Noise and Vibration in a Contra-Rotating Fan

Table 2

The natural frequency of the first 6 steps of the blades with different axial spacing.

(a) Rotor 1

Order	Natural frequency of rotor 1/(Hz)
	0.3 chord	0.5 chord	0.7 chord	0.9 chord	1.1 chord
1	182.41	182.42	182.42	182.41	182.39
2	584.51	584.52	584.53	584.5	584.46
3	725.69	725.71	725.78	725.73	725.6
4	1234	1234	1234	1234	1234
5	1328.6	1328.6	1328.7	1328.6	1328.5
6	1667.1	1667.2	1667.4	1667.2	1666.9

(b) Rotor 2

Order	Natural frequency of rotor 2/(Hz)
	0.3 chord	0.5 chord	0.7 chord	0.9 chord	1.1 chord
1	179.5	179.49	179.47	179.51	179.49
2	577.03	577	576.96	576.98	577.04
3	724.62	724.56	724.43	724.63	724.63
4	1208.8	1208.8	1208.7	1208.8	1208.8
5	1318.7	1318.6	1318.5	1318.6	1318.7
6	1656.4	1656.3	1655.9	1656.3	1656.5