Oscillation of Impinging Jet with Generation of Acoustic Waves

Abstract

This paper presents an oscillatory phenomenon of the underexpanded jet which issues from a convergent nozzle and impinges on a flat plate perpendicularly. As the characteristics of the generating noise deeply depend on the oscillation of the impinging jet, the flow field is visualized using the shadowgraph method and the pressure on the plate is measured to classify the oscillation modes for different parameters such as the nozzle pressure ratio and the distance between the nozzle and the plate. For the comparison, the jet is numerically simulated using Total Variation Diminishing (TVD) scheme under the assumption of the non-viscous flow. Simulating the impinging main jet and the radial wall jet on the plate separately, the sound waves propagating around the jet are shown and the frequency of the oscillation for each jet is tested. The wall-jet oscillation which is caused by the small vortices from the main jet occurs at high frequency when the nozzle-plate distance is comparatively small, while the main-jet oscillation induced by the grown vortices are shown to generate at large nozzle-plate spacing and the frequencies under such condition have well-known saw-tooth characteristics. With the correlation of pressure on the plate, three types of the oscillation – axisymmetric mode, whirling mode and non-regular pattern – are shown.

Feedback loop and upwind-propagating waves in ideally expanded supersonic impinging round jets

“…Given the aeroacoustic nature of the loop, it seems appropriate to use unsteady compressible simulations, which provide simultaneously all flow and acoustic variables and which have made spectacular progress over the last two decades. The axially symmetric or three-dimensional (3-D) Euler equations have for instance been solved by Sakakibara & Iwamoto (2002) in order to study the oscillatory phenomenon of an underexpanded jet impinging on a flat plate perpendicularly. Similarly, Kim & Park (2005) and Loh (2005) carried out simulations using the axisymmetric Navier-Stokes equations.…”

Experimental and Numerical Analysis on Noise Characteristics of Parallel Multiple Jets Obliquely Impinging on a Flat Surface in the Steel Slab Scarfing

“…This makes difficult to capture the time resolution of the sound field. Bogey et al, [ 15 ] Shur et al, [ 16 ] Uzun et al, [ 17 ] Rubel, [ 18 ] Zhang et al, [ 19 ] and Modak et al [ 20 ] have studied the flow, whereas Sakakibara and Iwamoto, [ 21 ] Dhamanekar and Srinivasan, [ 22 ] Mankbadi et al, [ 23 ] Nonomura et al, [ 24 ] and Brehm et al [ 25 ] have reported on aspects related to the acoustic noise of the single impinging jet. They have demonstrated that the nozzle geometry, impact height, impact angle, and Reynolds number affect the characteristics of the acoustic source as well as the sound propagation.…”

Effect of non-equilibrium homogeneous condensation on the self-induced flow oscillation of supersonic impinging jets

“…Numerical as well as both experimental and numerical simulations of unsteady impinging jets have also been carried out. Among them, some investigations involved in studying the self-induced oscillation [14], instabilities [15,16], modes of oscillation [17], near-field noise [18], TVD simulations [3], [19] to study the oscillations and generation of acoustic waves, Large Eddy Simulation [20], flow behavior coaxial impinging jets [21], etc. Recently, Yaga et al [22] conducted 3D investigations on the flow characteristics of rectangular under-expanded impinging jets both experimentally and numerically.…”