Contribution to the analysis of liquid macroflow in a cylindrical vessel with a high speed impeller

1981 ◽  
Vol 46 (4) ◽  
pp. 963-974 ◽  
Author(s):  
Jaroslav Medek ◽  
Ivan Fořt
Keyword(s):  
Flow Rate ◽  
Inclination Angle ◽  
Turbulent Diffusion ◽  
High Speed ◽  
Volumetric Flow Rate ◽  
Cylindrical Vessel ◽  
Lower Edge ◽  
Blade Number

In hitherto published studies the investigation of liquid macroflow in a vessel with an impeller has been concentrated mostly on the assessment of the volumetric flow rate through the impeller. Due to molecular and turbulent diffusion, however, significant exchange of mass and momentum occurs between this flow and the neighbouring charge. The extent of this induced volumetric flow rate has not been systematically investigated. This contribution attempts at the assessment of the induced, and total volumetric flow rate components in a vessel, in the plane of rotation of the lower edge of an impeller with flat inclined blades, in dependence on the blade number and the inclination angle between the blade and this plane.

Effect Of The Rib Inclination Angle On Liquid Film Spreading Over The Structured Surface

2015 ◽  
Vol 10 (1) ◽  
pp. 42-49
Author(s):  
Aleksandr Pavlenko ◽  
Oleg Volodin ◽  
Vladimir Serdyukov
Keyword(s):  
Liquid Film ◽  
Flow Rate ◽  
Inclination Angle ◽  
High Speed ◽  
Film Flow ◽  
Complex Geometry ◽  
Experimental Studies ◽  
Local Flow ◽  
Structured Packing ◽  
Film Spreading

Results of experimental studies on hydrodynamics of the film flow of liquid nitrogen over the surface of the single elements of structured packing are presented. The effect of inclination angle of the large ribs and perforation on the zones of liquid film spreading over the corrugated surface with microtexture at different Reynolds numbers of the film is shown based on a comparison of experimental data. It is shown that the angle of large rib inclination has a significant influence on redistribution of the local flow rate of liquid flowing on the surface with complex geometry. Analysis of results of the high-speed video revealed that in a vicinity of the vertical lateral edges of corrugated plates, the intense rivulet flows are formed, including those with separation from the film flow surface. This negative factor can lead to significant liquid accumulation and flow near the vertical edges of the structured packing and on the inner wall of the heat exchanging apparatuses and, finally, to a significant increase in the degree of maldistribution of local liquid flow rate over the crosssection, for instance, of the distillation columns.

Numerical and experimental investigation of flow phenomena in rotating step-holes for direct-spray-cooled electric motors

2020 ◽  
pp. 146808742091804
Author(s):  
Christopher Beck ◽  
Jürgen Schorr ◽  
Harald Echtle ◽  
Jasmin Verhagen ◽  
Annette Jooss ◽  
...  
Keyword(s):  
Flow Rate ◽  
Electric Motor ◽  
Rotational Speed ◽  
High Speed ◽  
High Efficiency ◽  
Volumetric Flow Rate ◽  
Dielectric Fluid ◽  
Electric Motors ◽  
Test Environment ◽  
Operating Points

Despite their high efficiency, electric motors are thermally limited in some operating points by several types of losses. Whenever temperature–critical components threaten to overheat, the performance is reduced for component protection (derating). The use of a suitable cooling concept may reduce the derating. The design of efficient cooling concepts of electric motors in traction drives with increased power densities is challenging, caused by the fact that the heat releases in the components vary considerably with the operating point. One option to reduce the temperatures is to place the heat sinks close to heat sources. Therefore, direct spray cooling with nozzles located in the rotor shaft is often used for cooling the end windings. The dielectric fluid (e.g. oil) is introduced into the mainly air-filled interior of the electric motor. In the following study, the behavior of the jet in the rotating step-holes at different volumetric flow rates is examined. To carry out the investigation, a new test rig and a novel optically accessible electric motor were designed. In this specifically designed test environment, the shape of the jets of different operating points is investigated by direct high-speed visualization. The cinematography setup is made of a four-light-emitting diode system in combination with a high-speed camera. A combined approach of experiment and simulation is used to find basic mechanisms of spray formation produced by rotating step-holes. Depending on the volumetric flow rate and the rotational speed, the direction of the oil jet gets more curved in relation to the rotating nozzle after exiting the small bore. If the deflection is large, the jet impinges on the wall of the large bore before reaching the end of the nozzle. The jet formation at the exit of the step-hole is mainly driven by the divergent forces in the liquid caused by impingement and the counteracting Coriolis force. Depending on the volumetric flow rate with constant rotational speed, different cross-sectional shapes of the jet at the exit are observed. These characteristic shapes can be grouped as a round undisturbed jet, strands with a connecting lamella and a C-shaped cross-section.

Analysis and Measurement of Effective Flow-Rate in Flood Grinding

2009 ◽  
Vol 626-627 ◽  
pp. 159-164 ◽  
Author(s):  
Chang He Li ◽  
Ya Li Hou ◽  
Yu Cheng Ding ◽  
Bing Heng Lu
Keyword(s):  
Boundary Layer ◽  
Flow Rate ◽  
High Speed ◽  
Good Description ◽  
Volumetric Flow Rate ◽  
Grinding Wheel ◽  
Work Surface ◽  
Grinding Fluid ◽  
Grinding Conditions ◽  
Grinding Machine

In the grinding process, grinding fluid is delivered for the purposes of chip flushing, cooling, lubrication and chemical protection of work surface. Due to high speed rotating grinding wheel, the boundary layer of air around the grinding wheel restricts most of the grinding fluid away from the grinding zone. Hence, conventional method of delivering grinding fluid that flood delivery is not believed to fully penetrate this boundary layer and, thus, the majority of the grinding fluid is deflected away from the grinding zone. The flood grinding typically delivers large volumes of grinding fluid was ineffective, especially under high speed grinding conditions. In the paper, a theoretical model is presented for flow of grinding fluid through the grinding zone. The model shows that the flow rate through the contact zone between the wheel and the work surface depends on wheel porosity and wheel speed as well as depends on nozzle volumetric flow rate and fluid jet velocity. Furthermore, the model was tested by a surface grinding machine in order to correlate between experiment and theory. Consequently, the effective flow-rate model was found to give a good description of the experimental results and the model can well forecast the effective flow-rate in flood delivery grinding.

Numerical Studies on the Performance of Saccardo Ventilation System in Emergency Fire Scenarios

2014 ◽  
Vol 527 ◽  
pp. 146-151
Author(s):  
Rouhollah Ganjiazad ◽  
Ali Kazemipour ◽  
Hossein Afshin ◽  
Bijan Farhanieh
Keyword(s):  
Flow Rate ◽  
Inclination Angle ◽  
Ventilation System ◽  
Volumetric Flow Rate ◽  
Smoke Plume ◽  
Numerical Studies ◽  
Air Jet ◽  
Before And After ◽  
Fire Scenarios ◽  
Inclination Angles

In this study, the influence of volumetric flow rate and inclination angle of air jet is evaluated on the performance of a Saccardo ventilation system in a straight rectangular tunnel in case of fire. Simultaneous effects of volumetric flow rate and inclination angle of jet exiting the Saccardo nozzle on the behavior of smoke plume is considered by studying the structure of velocity profile before the fire source. It is found that this factor has a remarkable influence on the behavior of smoke plume and therefore, on the temperatures experienced near the fire. Besides, the influence of tunnel slope on the performance of the Saccardo system to sweep the plume is investigated. It is shown that the slope effect on the behavior of smoke plume and temperature profiles is completely different for locations before and after the fire, in both negative and positive slopes. Finally a range of volumetric flow rates and inclination angles is proposed as the optimized range of performance in an emergency fire scenario.

The effects of volumetric flow rate and inclination angle on the performance of a solar thermal collector

2014 ◽  
Vol 78 ◽  
pp. 931-937 ◽  
Author(s):  
Ihaddadene Razika ◽  
Ihaddadene Nabila ◽  
Bey Madani ◽  
Hamdibacha Fatima Zohra
Keyword(s):  
Flow Rate ◽  
Inclination Angle ◽  
Volumetric Flow Rate ◽  
Solar Thermal ◽  
Solar Thermal Collector

Optical Flow Measurement of Cavitation in a Converging-Diverging Nozzle Using High-Speed Imagery

2015 ◽  
Author(s):  
Alan Duong
Keyword(s):  
Velocity Profile ◽  
Vapor Pressure ◽  
Flow Rate ◽  
High Speed ◽  
Volumetric Flow Rate ◽  
Cavitating Flow ◽  
Back Pressure ◽  
High Speed Photography ◽  
Choked Flow ◽  
Onset Of Cavitation

Cavitation is a phenomenon where liquids will vaporize when subjected to low pressures. Essentially, the pressure is reduced sufficiently such that the liquid boils at the given temperature. The highest pressure at which cavitation could occur is called the vapor pressure. However, the pressure associated with the onset of cavitation could be lower than the vapor pressure. This indicates the liquid exists under a meta-stable condition. The current research is investigating different aspects of cavitation and cavitating flow characteristics. Particle tracking using high-speed photography provided further insight as to what the velocity profile of cavitating flow may resemble. The research has shown that the cavitation that occurred in the current nozzle appears to have a laminar velocity profile. In the experiments that were conducted, it was also observed that as the back pressure of the downstream decreased, the volumetric flow rate would increase. However, a maximum volumetric flow rate was measured once the flow had begun cavitation regardless of the back pressure. This indicated that choked flow conditions likely exist within the nozzle. Choked flow within the nozzle indicates that near the region of the throat the fluid velocity has reached the speed of sound. Using high-speed photography, visualization of flow separation and recirculation was recorded. The information obtained from the research provides a more detailed description of the velocity profile near the onset of cavitation. The main objectives of this research were to obtain measurements of the overall flow for support of on-going research and analysis of nozzle flow cavitation. This study will provide a foundation for further and more detailed research into cavitation phenomena.

The pumping characteristics of screw rotors. I. The theory of calculation of the pumping capacity of screw rotors

1987 ◽  
Vol 52 (2) ◽  
pp. 357-371 ◽  
Author(s):  
František Rieger
Keyword(s):  
Present State ◽  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Screw Rotor ◽  
Screw Rotors

This paper summarizes the present state of the theory of calculation of the pumping capacity of screw rotors. The calculation starts from the equation for the volumetric flow rate of the flow between two unconfined plates modified by correction coefficients obtained from the relationships for the flow rate in simpler geometrical configurations to which the screw rotor may be, under certain circumstances, reduced.

scholarly journals Design and thermal characteristic analysis of motorized spindle cooling system

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110208
Author(s):  
Yuan Zhang ◽  
Lifeng Wang ◽  
Yaodong Zhang ◽  
Yongde Zhang
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Thermal Deformation ◽  
Cooling System ◽  
Thermal Characteristic ◽  
Water Flow Rate ◽  
Thermal Characteristics ◽  
Characteristic Analysis ◽  
Motorized Spindle ◽  
Experiment And Simulation

The thermal deformation of high-speed motorized spindle will affect its reliability, so fully considering its thermal characteristics is the premise of optimal design. In order to study the thermal characteristics of high-speed motorized spindles, a coupled model of thermal-flow-structure was established. Through experiment and simulation, the thermal characteristics of spiral cooling motorized spindle are studied, and the U-shaped cooled motorized spindle is designed and optimized. The simulation results show that when the diameter of the cooling channel is 7 mm, the temperature of the spiral cooling system is lower than that of the U-shaped cooling system, but the radial thermal deformation is greater than that of the U-shaped cooling system. As the increase of the channel diameter of U-shaped cooling system, the temperature and radial thermal deformation decrease. When the diameter is 10 mm, the temperature and radial thermal deformation are lower than the spiral cooling system. And as the flow rate increases, the temperature and radial thermal deformation gradually decrease, which provides a basis for a reasonable choice of water flow rate. The maximum error between experiment and simulation is 2°C, and the error is small, which verifies the accuracy and lays the foundation for future research.

Pahoehoe and aa in Hawaii: volumetric flow rate controls the lava structure

1990 ◽  
Vol 52 (8) ◽  
pp. 615-628 ◽  
Author(s):  
Scott K Rowland ◽  
George PL Walker
Keyword(s):  
Flow Rate ◽  
Volumetric Flow Rate
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