Newsletter  2026.3  Index

Theme : "The Eleventh JSME-KSME Thermal and Fluids Engineering Conference (TFEC11) " Preface Hyun Jin PARK, Shoichi MATSUDA, Chungpyo HONG Post-Lecture Summary: Engine Knock Prediction – Building on Combustion Fundamentals Kaoru MARUTA, Youhi MORII (Tohoku University) Electrical Tomography × Flow Visualization × Startups  – Chiba University Spin-off Startups and the Future of Fluid Engineering – Songshi LI, Masahiro TAKEI (Chiba University) Turbulent drag reduction effects by streamwise traveling waves with spanwise phase shifts Kyohei OISHI (Keio University), Senri MIURA (Keio University), Yusuke NABAE (Tokyo University of Science), Koji FUKAGATA (Keio University) Effect of a sidewall height on the instability of an inclined falling liquid film in a minichannel Shogo Matsui(Yokohama National University), Georg F. Dietze(CNRS, FAST, Université Paris-Saclay, Orsay), Koichi Nishino(Yokohama National University), Misa Ishimura(Yokohama National University) Development of a ReaxFF Force Field for CO2 Separation in PVAm/PVA Composite Membranes: Molecular-Level Insights into Aqueous Transport Mechanism Yukiko TOMITA, Kohei SATO, Ikuya KINEFUCHI (Tokyo University) Flow characteristics of multiple jets and their flow in a chamber Asuka KONDO, Masaki FUCHIWAKI (Kyushu Institute of Technology) Experimental investigation of combined blowing-suction control on a Clark-Y airfoil Senri MIURA, Koji FUKAGATA (Keio University)

 

Flow characteristics of multiple jets and their flow in a chamber

Asuka KONDO Kyushu Institute of Technology	Masaki FUCHIWAKI Kyushu Institute of Technology

Abstract

Multiple jets are widely used in various manufacturing processes, including cleaning, drying, and surface treatment. Because the characteristics of multiple jets are related to mass transfer in chemical reactions, uniform nozzle flow velocities are required. However, in current equipment, nozzle flow velocities vary, with some nozzles having lower flow velocities than surrounding nozzles. Previous studies on nozzle jet characteristics have revealed that nozzle geometry and inlet conditions affect jet characteristics. However, the behavior of the liquid before it leaves the nozzle and its effect on the liquid flow at the outlet has not yet been clarified. To achieve uniform multiple jets, it is necessary to clarify the correlation between the liquid flow in the chamber and the jet characteristics and control these flows. Therefore, the purpose of this study is to clarify the flow characteristics in the chamber and elucidate the effect of these flows on the jet characteristics to achieve uniform jet characteristics. Specifically, by changing the inlet conditions of the multiple jets and performing transient analysis, we captured the liquid flow in the chamber and correlated it with the nozzle jet flow velocity. It is known that multiple parallel flows affect each other depending on the distance and flow velocity. Because it is not easy to change the internal structure of this model, the flow within the chamber was changed by changing the flow interference rather than the structure. Therefore, to clarify how the liquid flow within the chamber changes due to changes in the inlet flow rate ratio, the total inlet flow rate was kept constant (Q = 110 L/min) and two different inlet flow rate ratios were given. As a result, it was found that by providing flows with different flow rates to multiple inlets, it was possible to suppress the formation of large circulating flows within the chamber, and by equalizing the pressure distribution within the chamber, it was possible to obtain jets with uniform flow rates from all nozzles.

Key words

CFD, Jet, Pipe flow, Vortex flow

Figures

Fig. 1 Analysis model

(a) Evaluation cross section       　       　  (c) V_a:V_b = 1:2 (Q = 110 L/min)
Fig. 2 Pressure distribution in the nozzle and velocity vector at the nozzle outlet

(a) V_a:V_b = 1:1 (Q = 110 L/min)            (b) V_a:V_b = 1:2 (Q = 110 L/min)
Fig. 3 Vorticity contour in the chamber