Structures, jet-and-crossflow interactions, and cross-plane entrainment mechanisms of jet and controlled jet in crossflow

Name: Intakarn Na Takuathung

Organization : Chulalongkorn University. Faculty of Engineering

Name: Asi Bunyajitradulya

Organization : Chulalongkorn University. Faculty of Engineering

Email : asi.b@chula.ac.th

keyword: Jet in crossflow

ThaSH: Jets -- Fluid dynamics

; Counter-rotating vortex pair (CVP)

; Control jets

; Entrainment

Abstract: Structures, jet-and-crossflow interactions, and cross-plane entrainment mechanisms of jet and controlled jet in crossflow (JICF and cJICF) at high jet-to-crossflow effective velocity ratio r of 12 are investigated. The results are then compared to JICF at lower r of 4 as reported by Sornphrom and Bunyajitradulya (2016). On the one hand, in order to determine the volumetric entrainment ratio (E) more directly, velocity field information from Stereoscopic Particle Image Velocimetry (SPIV) with (A) jet-fluid only seeding scheme is required. On the other hand, in order to investigate the jet-fluid mixture structures, jet-and-crossflow interactions, and consequently the entrainment mechanisms, additional velocity field information from SPIV with (B) both jet and crossflow fluids seeding scheme is required. As a result, (C) the pure crossflow fluid property can be approximated from the scheme C=B-A, employed earlier by Sornphrom and Bunyajitradulya (2016). The experiment is conducted for a baseline JICF at r of 12; crossflow Reynolds number (Recf) of 3,100; jet Reynolds number of (Rej) of 37,000; the jet initial velocity profile of fully-developed turbulent pipe flow. In the cJICF case, case I165, a pair of azimuthal control jets is injected steadily and radially into the main jet before the jet exit at the azimuthal position (+θ) of +165° and the control jets to main jet mass flow rate ratio (rm) of 4 percent. The present results show the followings. I) The injection of the control jets at θ=+165° helps enhancing entrainment over JICF, consistent with earlier result by Wangkiat et al. (2015). II) When compared to JICF at lower r of 4, similar five flow features are observed in both the present cases of JICF and I165. In addition, similar cross-plane entrainment mechanism is also observed: namely, 1) Jet- CVP-induced surrounding pure crossflow vortical motion, 2) Jet-CVP-induced vertical channel of high upward flow, and 3) Free-jet like entrainment of jet kidney-shaped structure. However, some differences can also be identified. III) When compared JICF at higher r of 12 to that at lower r of 4, it is found that the region of relatively intense entrainment at higher r occurs earlier during the sequence of downward-inward motion of the jet-CVP-induced pure crossflow vortical motion while that at lower r occurs later during the sequence of inward-upturn motion. This results in the region of intense entrainment of JICF at higher r being located more towards the high-lateral side of the jet than that of lower r, which is located more towards the bottom-center of the jet, i.e., in the converging section of the vertical channel of high upward flow. IV) On the other hand, when compared JICF and I165 at this higher r of 12, it is found that while the region of intense entrainment of JICF is mainly in the lateral-lower half of the jet, that of I165 spans in both the lateral-lower and -upper halves of the jet.

King Mongkut's University of Technology North Bangkok. Central Library

Address: BANGKOK

Email: library@kmutnb.ac.th

Created: 2016

Modified: 2026-10-07

Issued: 2026-10-07

บทความ/Article

application/pdf

BibliograpyCitation : In Chulalongkorn University Faculty of Engineering. The 7th TSME International Conference on Mechanical Engineering 2016 (TSME-ICoME7) (TSF0016). Bangkok : Chulalongkorn University

eng

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