Velocity Statistics of a Fully Pulsed Round Jet in Streamwise Direction

Abstract

In this paper, statistical quantities of a fully pulsed round jet along the jet centerline are reported. A range of the Reynolds (1.5 x 104 < Re < 4 x 104) and Strouhal (0.0064 < St < 0.0076) numbers is used to generate the jet. Physically this unsteady jet produces a series of distinct pulses due to the excitations. The mechanically excitations lead to the appearance of pulse dominated and high turbulence steady jet region in which their existence is of a strong dependence on the level of the controlled parameters. After the pulse merging completes the pulsed jet alters to a self-preserving steady jet with a significantly higher turbulence intensity. Under a constant mass flow rate the pulsed jet tends to be more fluctuating at a less intense pulsation thus permitting the endurance of the normalized periodic component and a more rapid velocity decay in the pulse-dominated region.

Movable shark scales act as a passive dynamic micro-roughness to control flow separation

“…A pulsating jet (diameter 1 mm, jet exit about the size of 5-6 scales) with a maximum exit velocity of approximately 10 m s −1 , was placed in the near vicinity of the scales. Due to mixing with the ambient water, the core jet velocity decreases quickly from the jet exit and, according to published data on pulsating jets in a similar Re range [22], within 1 cm (10 jet diameters) of the exit the peak velocity would reduce to approximately 5 m s −1 . Since the jet exit was also located above the surface (with flow moving parallel to it and the jet piping did not touch the skin), it is difficult to estimate the exact flow velocity that was induced on the scales themselves which resulted in scale bristling.…”

Analisis Penentuan Pusat-Pusat Pertumbuhan (Growth Pole) dan Wilayah Belakang (Hinterland) Provinsi Kalimantan Tengah

“…Pada beberapa penelitian, pengelompokan daerah melalui dukungan metode Tipologi Klassen, menggunakan pendapatan perkapita sebagai variabel tingkat kemakmuran (Ardila, 2012;Emalia & Farida, 2018;Panjiputri, 2013;Pratiwi & Kuncoro, 2016;Pratomo, 2014). Mengingat tingkat kemakmuran kabupaten/kota tidak hanya diukur oleh tingkat pendapatan perkapita yang hanya menunjukan aspek ekonomi saja.…”

“…Berdasarkan penelitian terdahulu, penentuan pusat pertumbuhan menggunakan analisis Scallogram untuk merefleksikan kemampuan daerah dalam memberikan pelayanan umum (sosial dan ekonomi) kepada masyarakat seperti kesehatan, pendidikan, dan pasar (Ardila, 2012;Emalia & Farida, 2018;Nainggolan, 2013;Pratomo, 2014;Putra, Badjuri, & Anifatul, 2017 (Emalia & Farida, 2018;Panjiputri, 2013;Pratiwi & Kuncoro, 2016). Pada beberapa penelitian, perhitungan interaksi antar daerah menggunakan variabel penduduk dan jarak dalam analisis gravitasinya (Ardila, 2012;Emalia & Farida, 2018;Nainggolan, 2013;Panjiputri, 2013;Putra et al, 2017).…”