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Số người truy cập: 75,104,053

 VORTEX DYNAMICS OF A PULSED JET FLOW AT VARIOUS FORCING FREQUENCIES
Tác giả hoặc Nhóm tác giả: Minh Duc Le, Duc Van Pham, Tan Tien Huynh, Quang Trung Nguyen, Dinh Nghia Duong
Nơi đăng: Proceeding of ICOMMA-2020; Số: xxx-xxx;Từ->đến trang: xxx-xxx;Năm: 2020
Lĩnh vực: Khoa học công nghệ; Loại: Bài báo khoa học; Thể loại: Quốc tế
TÓM TẮT
ABSTRACT
The effects of excitation frequency on vortex characteristics and shear layers of a round jet were
investigated numerically. The jet with a diameter of 5 mm was issued from a nozzle assembly and
connected to the downstream region via a 5mm diameter and 600 mm length of the tube. The forced frequencies were performed at 5 Hz, 50 Hz, and 250 Hz, while the jet exit Reynolds number was fixed at 1660. The vortex characteristics were predicted using the turbulent model of Reynolds-averaged Navier Stokes (RANS) type. The results show that large turbulent kinetic energy and vorticity regions are located around the shear layers of the forced jet where the vortex rings existed. The vortex rings are induced firstly at the jet exit, growth, and move quickly downstream along the axial direction during a forcing cycle. The size of vortex rings formed at a low frequency is much larger than that at a high frequency. The jet structures are earlier break up into small eddies as increasing the forcing conditions. The formation process of vortex rings moves upstream gradually as increasing the forcing frequency. The spreading of the forced jet is significantly larger than that of the unforced jet. The evolutions of radial and axial velocities, vorticities, and turbulent kinetic energies of the forced jet at various frequencies were presented and discussed in the present study.
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