Home
Giới thiệu
Tài khoản
Đăng nhập
Quên mật khẩu
Đổi mật khẩu
Đăng ký tạo tài khoản
Liệt kê
Công trình khoa học
Bài báo trong nước
Bài báo quốc tế
Sách và giáo trình
Thống kê
Công trình khoa học
Bài báo khoa học
Sách và giáo trình
Giáo sư
Phó giáo sư
Tiến sĩ
Thạc sĩ
Lĩnh vực nghiên cứu
Tìm kiếm
Cá nhân
Nội dung
Góp ý
Hiệu chỉnh lý lịch
Thông tin chung
English
Đề tài NC khoa học
Bài báo, báo cáo khoa học
Hướng dẫn Sau đại học
Sách và giáo trình
Các học phần và môn giảng dạy
Giải thưởng khoa học, Phát minh, sáng chế
Khen thưởng
Thông tin khác
Tài liệu tham khảo
Hiệu chỉnh
Số người truy cập: 107,495,077
Time-averaged flow characteristics of pulsed swirling coaxial jets with annular blockage
Tác giả hoặc Nhóm tác giả:
S.R.Jufar and Minh Duc Le
Nơi đăng:
Experimental Thermal and Fluid Science (SCIE, Q1);
S
ố:
134;
Từ->đến trang
: 110602;
Năm:
2022
Lĩnh vực:
Khoa học công nghệ;
Loại:
Bài báo khoa học;
Thể loại:
Quốc tế
TÓM TẮT
An experimental study was conducted to investigate the mixing and time-averaged turbulence characteristics of pulsed swirling coaxial jets with annular blockage. The study was conducted using a custom-made device by pulsing the central jet using acoustic excitation. A high-speed camera was used to identify the flow structures. The mixing characteristics and the turbulence properties of the flow were studied through a hot-wire anemometer and high-speed particle image velocimetry (PIV) techniques. Flow visualization, mean velocity profiles, vorticity and Reynolds stress fields, and Lagrangian time and length scales were used to investigate the turbulence and mixing characteristics of the flow. The flow was excited under two distinct conditions. At the lower pulsation intensity, mixing was shown to improve near the exit because of the entrainment induced during the growth of the periodic vortex rings. At the higher pulsation intensity, mixing was shown to improve further downstream due to increased jet spreading caused by the breakup of the vortex rings. Investigation of the ensemble average flow field showed that the structure of the unexcited flow was altered because of the excitation. At the higher pulsation intensity, a stagnation point was formed on the centerline which was not observed in the unexcited flow and excitation at the lower pulsation intensity. Within a single period, the position of the stagnation point moved cyclically along the centerline. In comparison with the naturally evolving jets, excitation at the higher pulsation intensity has reduced the mean axial velocity allowing better mixing of the jets in the downstream area.
ABSTRACT
An experimental study was conducted to investigate the mixing and time-averaged turbulence characteristics of pulsed swirling coaxial jets with annular blockage. The study was conducted using a custom-made device by pulsing the central jet using acoustic excitation. A high-speed camera was used to identify the flow structures. The mixing characteristics and the turbulence properties of the flow were studied through a hot-wire anemometer and high-speed particle image velocimetry (PIV) techniques. Flow visualization, mean velocity profiles, vorticity and Reynolds stress fields, and Lagrangian time and length scales were used to investigate the turbulence and mixing characteristics of the flow. The flow was excited under two distinct conditions. At the lower pulsation intensity, mixing was shown to improve near the exit because of the entrainment induced during the growth of the periodic vortex rings. At the higher pulsation intensity, mixing was shown to improve further downstream due to increased jet spreading caused by the breakup of the vortex rings. Investigation of the ensemble average flow field showed that the structure of the unexcited flow was altered because of the excitation. At the higher pulsation intensity, a stagnation point was formed on the centerline which was not observed in the unexcited flow and excitation at the lower pulsation intensity. Within a single period, the position of the stagnation point moved cyclically along the centerline. In comparison with the naturally evolving jets, excitation at the higher pulsation intensity has reduced the mean axial velocity allowing better mixing of the jets in the downstream area.
[
https://doi.org/10.1016/j.expthermflusci.2022.110602
]
© Đại học Đà Nẵng
Địa chỉ: 41 Lê Duẩn Thành phố Đà Nẵng
Điện thoại: (84) 0236 3822 041 ; Email: dhdn@ac.udn.vn