The Effect of Orifice Diameter to the Acoustic Signals Captured at the Cold Part of a Ranque-Hilsch Vortex TubeWirachman Wisnoe, Khairil Muhaimin Abd Rahman, Yusman Istihat and Valliyappan David NatarajanMATEC Web Conf., 95 (2017) 07019DOI: https://doi.org/10.1051/matecconf/20179507019