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222 Advances in Productive, Safe, and Responsible Coal Mining

Cutting bits Mounting plate Helical vanes

Face Discharge
side side

Face ring Bit holders Cylindrical body

Fig. 12.2 Drawings of a longwall-cutting drum showing its various components.

12.4.1.1 Noise source identification
Although the cutting drums were found to be the dominant sound-radiating compo-
nents on a longwall shearer, it was not clear what components of the drums were radi-
ating most of the noise. To identify these components, a panel contribution analysis
was performed using the boundary element model and dividing it into two parts: the
cylindrical shell and the vanes. During this analysis, only one of these parts is assumed
flexible while the other is set to be rigid. Analysis results indicated that the four vanes
are the critical components of the drum that generate noise of much higher amplitude
as compared with the noise generated by the cylindrical shell [19]. However, because
of the large dimensions of the vanes, more detailed information was needed.
In order to gain a better understanding of the critical sound-radiating components
on the drum, a further panel contribution analysis was performed. In this analysis, the
whole drum was divided into three parts: the cylindrical shell face, inner vane segment
faces, and outer vane segment faces, as shown in Fig. 12.3.
The excitation was applied in the same manner as in the prior work [20], and the
predicted overall sound energy distribution is shown in Fig. 12.4. Similarly, the energy

Fig. 12.3 FE-BE faces for: (A) whole drum, (B) cylindrical shell, (C) inner vane segments,
and (D) outer vane segments.