Numerical simulations of the flow and sound fields of a heated axisymmetric pulsating jet

The flow and sound fields of a heated axisymmetric pulsating jet have been investigated by direct numerical solution of the compressible Navier-Stokes equations in cylindrical coordinates using highly accurate numerical methods. Effects of pulsating frequency and amplitude on the flow structure and sound generation have been examined. The results show that the organized unsteadiness associated with the periodic pulsation leads to a variety of vortical structures in the pulsating flow field. The pulsating frequency and amplitude strongly affect the vortical flow structures and the radiated sound fields. At the higher pulsating frequency, the vortices in the pulsating jet become smaller and the radiated sound field has smaller wavelength. The pressure fluctuation amplitude of the sound field is inversely proportional to the distance from the sound source. Both the larger pulsating frequency and larger pulsating amplitude lead to stronger sound emissions from the pulsating jet. It has been found that the pressure fluctuation amplitude of the sound field is approximately proportional to the pulsating amplitude and frequency.