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Masaru Sumida,Takahiro Kamahara 한국유체기계학회 2022 International journal of fluid machinery and syste Vol.15 No.3
T his study involved an experimental investigation of the distribution of pulp fiber concentration in t he region behind a partitio n plate with a taper ed trailing edge inserted in a convergen t channel The channel was modeled at the laboratory scale for the dispersio n and rectification components of the headbox passage in a papermaking machine. For t he exp e r iment s the inlet cross se c tional average flow velocity U a , of an actual pulp suspension was in the range of 0.03 3.3 m/s . T he flow was visualized and the fiber concentration distribution was measured. Subsequently, t he effects of the flow velocity on t h e time averaged and fluctu a ting fiber concentration distributions C a and C’ respectively ) in the flow direction were examined through compar i so n s with those in the case s where the plate was installed in the parallel channel or had a simple rectangular e d ge In the convergent chan n el with the taper ed trailing edge, t he fiber concentration def ect behind the plate was reduced abruptly . Moreover, the uniformity of the fiber concentration distribution at the convergence exit did not vary with the flow veloci t y , thereby having a low val u e. Overall, the fundamental observations obtained in this study can contribute to the optimization and improve ment of the headbox channel s of papermaking machine s
Masaru Sumida,Tomoyuki Sedokubo 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.2
In this study, we analyze the flow characteristics of pulp suspensions in a sudden expansion channel, which is used as a tube bank in papermaking machines. Flow visualization using a light section method and measurements of time averaged and fluctuating fiber concentrations, Ca and C’, and pressure were performed. The experiments were carried out on pulp suspensions with a bulk fiber concentration (Cs) of 0 2.0 wt% in a channel with an expansion ratio of β = 2 at varied average velocities (Ua) of 0.04-6.6 m/s. We examined the effect of flow velocity on the changes in concentration and pressure distributions along the channel axis The distribution of the pulp fiber concentration behind the sudden expansion significantly changes depending on the flow state in the upstream channel before the expansion. In particular, for low and moderate velocities, the flow field is characterized in the main flow region consisting of flocculated plug fibers and a recirculation region with a low concentration near the expansion corner by a type of streamline originated from the thin water layer in the upstream channel. The distribution of Ca shows a tongue shaped structure in the central part of the cross section and C’ is large near the annulus streamline As the velocity is further increased, the flocculated fibers gradually disperse and the distributions of Ca and C’ become almost uniform. In addition, the uniformity of fiber concentration does not change much in the section downstream from a distance 10 times the step height from the sudden expansion plane.
Experimental Study of Pulp Suspension Flow in a Channel with Application to Papermaking
Masaru Sumida,Taro Fujimoto 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.3
In this study, the flow characteristics of a pulp suspension in a modeled headbox channel containing a screen-type circular cylinder were examined experimentally. The distributions of the pulp fiber concentration and the axial velocity of downstream wake of the cylinder were obtained using the transmitted light attenuation method and particle image velocimetry, respectively. The influence of flow velocity and the degree of pulp fiber dispersion were explained. From this information, we explored the feasibility of improving the efficiency of the hydraulic headbox of a papermaking machine.
Masaru Sumida 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.2
An experimental study was performed on the fiber-concentration distributions of wood pulp liquid flowing through a divergent tube at a divergence angle of θ = 12°.The study was conducted to verify the tube’s effectiveness for application to the tube banks of papermaking machines. Experiments were conducted at bulk pulp-fiber concentrations of Cs = 0.2-0.6 wt% and inflow velocities of Ua = 0.1-2 m/s. The flow in the horizontal plane that contained the tube axis was visualized using the light-section method. In addition, the distributions of the time-averaged and fluctuating fiber concentrations (Ca and C’, respectively) were measured. We then investigated the effect of the average flow rate on the variations in the directions of flow of the concentration distributions. Ata low flow rate (Ua<0.3m/s), the fluid of the annular water layer formed in the upstream tube divided the flow into two in the divergent tube, and the Ca and C’ distributions exhibited shapes that had considerable differences in the cross-section. When the flow velocity was increased to Ua ≥ 0.5 m/s, the shape of the Ca distribution flattened, and C’ reduced gradually in the flow direction. The results related to the non-uniformity of fiber concentration demonstrated that the divergent tube is suitable for use in a tube-bank channel of the headbox of a papermaking machine.
Flow Characteristics of Pulp Suspension in a 90° Bend
Masaru Sumida,Kentaro Imamura 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.2
This study investigates the flow characteristics of pulp suspensions flowing through a 90° bend, which is used in the production system of an actual papermaking machine, e.g., for transporting the pulp suspensions from its stock reservoir to the header. Experiments were conducted on pulp suspensions with a fiber concentration Cs of 0.3 and 0.6 wt% and a bend with a diameter of 22 mm and a curvature radius ratio of 4.0. Flow visualization and measurements of the distributions of time-averaged fiber concentration Ca and axial velocity U were performed with a light section method and the particle image velocimetry (PIV) method, respectively, at representative bulk velocities and at various longitudinal stations. The influence of the flow rate on the changes of their distributions in the streamwise direction was examined. The flow characteristics of the pulp suspension depend on the flow pattern in the upstream straight tube and are greatly different from those of the single-phase water flow. For a low flow rate, the flocculated pulp fibers move without getting disentangled in the bend and the distribution of Ca shows a shape bias towards the inner wall side. As the flow rate is increased, Ca becomes larger in the outer part of the bend, and it changes into a rather flat distribution in the downstream tangent.
Developing Young Children\'s Scientific, Technological, and Social Competency through
Sumida ManabuFukada Shozo,Nakamura Hiroaki,Masukagami Masaru 환태평양유아교육연구학회 2007 Asia-Pacific journal of research in early childhoo Vol.1 No.1
There is growing recognition that young children are familiar with nai"ve physics, and construct their own theory about the natural world from early childhood. The research reported in this study focuses on intellectual play activities involving pendulums carried out by young children at a kinder - garten in Japan. Over the course of three weeks, five-year-old children partic - ipated in these pendulum play activities. They made pendulums by themselves, tried them out, compared them with others, identified variables in moving, controlled these variables, and communicated their findings with others in the context of free guided play. Throughout these activities, the children changed their sense making of pendulums as objects of art to objects for investigation. Simple equipment, such as weight balances and counters, seemed to develop their scientific and technological competency. Their findings were displayed on a communication board so that they could appreciate and discuss them with each other. Socio-cultural aspects of science and technology in our glob - al society are coming into the spotlight in the field of science education. Drawing on recent reviews, this paper proposes some implications in relation to the theory and practice of science activities for young children that aim to develop their scientific, technological, and social competency in early child - hood.