Wyniki wyszukiwania - BazTech

1

Air grilles designed to prevent backflows in natural ventilation stacks - experimental investigation

Koper Piotr, Szpank Dominik

Architecture Civil Engineering Environment

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2023

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Vol. 16, no. 2

161--169

EN

The paper presents the results of the experimental research on the air grills designed to stop backflows in natural ventilation stacks. For each grill pressure drop was measured for different airflow rates, in both flow directions. Two ∅ 100 mm grills working on different principles were tested: one with moving flaps, and one shaped in a way that should greatly increase the hydraulic losses during backflow. For comparison, the ordinary air grill was also tested. The results show that the grill with moving flaps works as intended. With only slightly higher hydraulic losses in the forward direction compared to ordinary grill, it shuts off the backflows almost completely. The other, diffuser-shaped grill doesn’t work as intended. It has very high hydraulic losses in both directions, and the effect of changing the air resistance with the reverse flow is barely noticeable.

2

Calculating study of the turbine at last stage flow field in the small volume flow condition

Jiang T., Jin J., Wang Z., Cao L., Li B.

Polish Maritime Research

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2017

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S 3

23--27

EN

Based on basic equation and boundary layer theory of pneumodynamics, the thesis conducts numerical modeling and theoretical analysis on the last stage of turbine characteristics at a small volume flow by using FLUENT, gives an emphasized analysis on the position of first occurrence of backflow and its expansion direction and comes up with flow structure of the turbine flow field at last stage in the small volume flow condition. In connection with specific experiments, it puts forward the flow model of backflow occurring in the last stage field and the solution to the model. The flow field at last stage for a 100MW turbine in the small volume flow condition that is calculated by using the model is basically in conformity to the actual result.

3

Numerical Analysis of The Effect of Hydrodynamics and Operating Conditions on Biodiesel Synthesis in a Rotor-Stator Spinning Disk Reactor

Wen Z., Petera J.

Chemical and Process Engineering

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2017

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Vol. 38, nr 2

265--281

EN

A rotor-stator spinning disk reactor for intensified biodiesel synthesis is described and numerically simulated in the present research. The reactor consists of two flat disks, located coaxially and parallel to each other with a gap ranging from 0.1 mm to 0.2 mm between the disks. The upper disk is located on a rotating shaft while the lower disk is stationary. The feed liquids, triglycerides (TG) and methanol are injected into the reactor from centres of rotating disk and stationary disk, respectively. Fluid hydrodynamics in the reactor for synthesis of biodiesel from TG and methanol in the presence of a sodium hydroxide catalyst are simulated, using convection-diffusion-reaction multicomponent transport model with the CFD software ANSYS©Fluent v. 13.0. Effect of operating conditions on TG conversion is particularly investigated. Simulation results indicate that there is occurrence of back flow close to the stator at the outlet zone. Small gap size and fast rotational speed generally help to intensify mixing among reagents, and consequently enhance TG conversion. However, increasing rotational speed of spinning disk leads to more backflow, which decreases TG conversion. Large flow rate of TG at inlet is not recommended as well because of the short mean residence time of reactants inside the reactor.

4

Flow of a visco-elastic fluid past a porous plate in a rotating system

Guria M., Jana R. N.

International Journal of Applied Mechanics and Engineering

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2013

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Vol. 18, no. 1

27--41

EN

An analysis is made on a steady flow of an incompressible visco-elastic fluid (of small memory) past a porous plate subject to uniform suction or blowing. The fluid and the plate rotate in unison with uniform angular velocity about an axis perpendicular to the plate. It is shown that for a visco-elastic fluid of small memory, a boundary layer is formed for uniform suction or blowing at the plate. It is found that the primary velocity increases whereas the secondary velocity increases near the plate and decreases away from the plate with an increase in the elastic parameter. The secondary flow shows flow reversal for a large elastic parameter. It is found that both primary and secondary velocities increase near the plate and decrease away from the plate with an increase in the rotation parameter. It is also found that the shear stress due to primary flow increases with an increase in either the elastic parameter or rotation parameter. On the other hand, the shear stress due to secondary flow decreases with an increase in the elastic parameter while it increases with an increase in the rotation parameter. The temperature distribution in the boundary layer is also determined. It is shown that elasticity leads to an increase in heat transfer at the plate.

5

Modele przepływu powrotnego w krótkim przewodzie mlecznym aparatu udojowego pracującego przy pulsacji jednoczesnej i przemiennej

Pawlak T., Luberański A., Szlachta J.

Inżynieria Rolnicza

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2006

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R. 10, nr 4(79)

83-89

PL

Znaleziono formułę matematyczną opisującą wpływ wybranych parametrów ciśnieniowych na intensywność przepływu zwrotnego Pp w krótkim przewodzie mlecznym aparatu udojowego pracującego przy pulsacji jednoczesnej i przemiennej. Potwierdzono przydatność modeli przy współczynniku determinacji R2 powyżej 0,7.

EN

A mathematical formula has been found to describe the impact of selected pressure parameters on return flow intensity Pp in the short milk pipe of the milking unit working with simultaneous and alternate pulsation. The suitability of models with the determination coefficient R2 above 0.7.

6

Analiza właściwości fizykochemicznych osadów dennych z cofki zbiornika rybnickiego w aspekcie ich wykorzystania do celów nieprzemysłowych

Loska K., Cebula J., Wiechuła D.

Gospodarka Wodna

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2002

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Nr 7

292-294

PL

Wykonano oznaczenia zawartości metali oraz azotu i fosforu w próbkach osadów pobranych z czterech stanowisk. Porównanie wyników z wartościami normatywnymi wykazało, że osady te po odwodnieniu mogą być wykorzystane w rolnictwie.

EN

Determination of the content of metals, nitrogen and phosphorus in the samples of bottom sediments taken from four measuring stations have been carried out. Comparison of results with standard values indicated that the sediments after dewatering may be utilized in the agriculture.