scholarly journals A Study on the Flow Mechanism Within Centrifugal Impeller Channels

1975 ◽  
Author(s):  
Shimpei Mizuki ◽  
Ichiro Ariga ◽  
Ichiro Watanabe
Keyword(s):  
Secondary Flow ◽  
Flow Patterns ◽  
Centrifugal Impeller ◽  
Production Mechanism ◽  
Flow Mechanism ◽  
Design Point ◽  
Production Mechanisms

Investigations concerning the flow patterns within centrifugal impeller channels have been made for many years. However, many of the problems remain unresolved about the secondary flow and the loss production mechanism within impeller channels. In the present study, measurements of the flow mechanism within impeller channels under the off-design conditions were performed by employing yaw probes to compare the results with those at the design point. The impellers with straight radial blades employed in the present study were of the same configuration except the shroud profiles which made diffusion ratios different from each other. From the present results, it became clear that the loss production mechanisms and the flow patterns within impeller channels were essentially unvaried both under design and off-design operations. The results thus obtained by the present study were furthermore compared with the others to examine the reliability of these results.

scholarly journals A Simulation of Secondary Flow in Centrifugal Impeller Channel by a Stationary Three-Dimensional Curved Duct

1992 ◽  
Author(s):  
Shimpei Mizuki ◽  
Hoshio Tsujita
Keyword(s):  
Secondary Flow ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Flow Patterns ◽  
Centrifugal Impeller ◽  
Meridional Plane ◽  
Blade Surface ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Qualitative Similarity

A duct with three-dimensional curvatures was employed in order to investigate the complex secondary flow patterns similar to those within centrifugal impellers. The curvature within a pair of co-cylindrical surfaces of the duct simulates that within the meridional plane of an impeller, and the curvature within the other pair of co-cylindrical surfaces perpendicular to the above-mentioned surfaces simulates the effect of the Coriolis force within the blade-to-blade surface. The computed and the measured results showed the qualitative similarity of the secondary flow patterns to those within centrifugal impellers except the effects of pressure rise by the centrifugal force generated by the impeller rotation and the tip leakage flow.

Unsteady Flow Phenomena in Rotating Centrifugal Impeller Passages

1970 ◽  
Vol 92 (1) ◽  
pp. 65-71 ◽  
Author(s):  
E. Lennemann ◽  
J. H. G. Howard
Keyword(s):  
Unsteady Flow ◽  
Secondary Flow ◽  
Centrifugal Impeller ◽  
Bubble Flow ◽  
Hydrogen Bubble ◽  
Visualization Technique ◽  
Rotating Systems ◽  
Flow Phenomena ◽  
Relative Flow ◽  
Zero Flow

The phenomena of unsteady relative flow observed in a centrifugal impeller passage running at part capacity and zero flow are discussed. The mechanisms of passage stall for a shrouded and unshrouded impeller are investigated and a qualitative correlation is developed for the influence of secondary flow and inducer flow on the passage stall. The hydrogen bubble flow visualization technique is extended to higher velocities and rotating systems and provides the method for obtaining the experimental results.

Optimization and Investigation on the Impact of Centrifugal Impeller Blade Thickness Distribution on Hydro-Induced Vibration

2018 ◽  
Author(s):  
B. Qian ◽  
D. Z. Wu
Keyword(s):  
Secondary Flow ◽  
Thickness Distribution ◽  
Suction Side ◽  
Centrifugal Impeller ◽  
Impeller Blade ◽  
Streamwise Location ◽  
Unbalanced Rotor ◽  
Blade Thickness ◽  
Vibration Performance ◽  
The Impact

The vibration performance of centrifugal impellers is of great importance for pumps in some application areas such as automobiles and ships. Apart from mechanical excitations for instance, unbalanced rotor and misalignment, attentions should be concentrated on the hydraulic excitations. The complex internal secondary flow in the centrifugal impeller brings degradation on both hydraulic and vibration performances. On the purpose of repressing the internal secondary flow and alleviating vibration, an attempt of optimization by controlling the thickness distribution of centrifugal impeller blade is given. The vibration performances of the impellers are investigated numerically and experimentally. Meanwhile, further study on the mechanism of the influence of the thickness distribution optimization on vibration is conducted. There is a relative velocity gradient from suction side (SS) to pressure side (PS) due to the Coriolis force, which causes non-uniformity of energy distribution. By means of thickness distribution optimization, the impeller blade angle on the PS and SS along the blade-aligned (BA) streamwise location is respectively modified and therefore the flow field can be improved.

scholarly journals Variations in the altitude of the F2 peak associated with trough-formation processes

1996 ◽  
Vol 14 (6) ◽  
pp. 628-636 ◽  
Author(s):  
R. I. Crickmore ◽  
B. Jenkins ◽  
G. J. Bailey
Keyword(s):  
Wind Velocity ◽  
Electron Concentration ◽  
Neutral Wind ◽  
Formation Processes ◽  
Production Mechanism ◽  
Causal Mechanisms ◽  
F Region ◽  
Novel Approach ◽  
Concentration Peak ◽  
Production Mechanisms

Abstract. A novel approach is described which can help to determine, from ground-based data, which of the possible production mechanisms for the mid-latitude F-region ionospheric trough is dominant during a particular event. This approach involves numerically modelling the possible causal mechanisms of the mid-latitude trough to see how each will affect the altitude of the F2-layer electron-concentration peak (hmF2), and then comparing these predictions with the observed variation of hmF2 during trough formation. The modelling work predicts that, if the neutral-wind velocity does not vary, hmF2 will remain almost constant if the trough is formed via stagnation, but will rise if it is formed as a result of high ion velocities or neutral upwelling. Observations made at Halley (76°S, 27°W, L=4.2), Antarctica, show that most frequently the only changes in hmF2 during trough formation are those expected due to variations in the neutral wind, which suggests that stagnation is the most common production mechanism. During the most geomagnetically active night studied, on which Ap varied between 18 and 32, there was a rise in hmF2 that cannot be explained by changes in the neutral wind. On this night the plasma also decayed faster, and the poleward edge of the trough was seen earlier than on other nights. These differences, together with the fact that the ion velocities remained relatively low, suggest the trough was caused by a change in neutral composition, possibly advected into the observing area.

scholarly journals Formation of energy efficient start-brake modes of the frequency-controlled electric drive in production mechanism

2019 ◽  
Vol 104 ◽  
pp. 01006
Author(s):  
Maxim Filimonov ◽  
Nicolay Karnaukhov ◽  
Eugeny Lukyanov ◽  
Dmitry Smyatsky ◽  
Roman Mironenko
Keyword(s):  
Energy Efficient ◽  
Supply Voltage ◽  
Asynchronous Motor ◽  
Electrical Power ◽  
Production Mechanism ◽  
Mass Model ◽  
Electrical Drive ◽  
Asynchronous Motors ◽  
Production Mechanisms ◽  
Nominal Mode

this article the energy efficient frequency way of starting of production mechanisms electrical drive with low power asynchronous motors (from 90 Wt to 5 kWt) is proposed. To provide this With the goal of electrical losses decreasing during asynchronous motor starting the Pontryagin Maximum Principle have been applied by the authors when analysing of two-mass model of production mechanism frequency controlled electrical drive. In result of calculations for frequency controlled electrical drive of production mechanism with 90 Wt power asynchronous motor of the model 4AA50A2 Dependencies of amplitude and frequency of supply voltage by the time are obtained. These dependencies confirm possibility of decreasing the electrical power losses with different values of motor shaft load torques. In compare with the other ways of asynchronous motor starting (for example U/f=const) they allow to decrease the electrical losses more then two times in nominal mode.

scholarly journals Observation and analysis of long-periodic modes in a confluence with dominant tributary inflow

2018 ◽  
Vol 40 ◽  
pp. 05043
Author(s):  
Laurent Schindfessel ◽  
Tom De Mulder ◽  
Mia Loccufier
Keyword(s):  
Numerical Simulations ◽  
Secondary Flow ◽  
Significant Influence ◽  
Laboratory Experiments ◽  
Flow Patterns ◽  
Modal Decomposition ◽  
Periodic Oscillations

Confluences with dominant tributary inflow are found to exhibit long-periodic alternations of the flow patterns. They are shown to exist both in laboratory experiments and in numerical simulations. By means of a modal decomposition, insight is given into these long-periodic oscillations. The origin of these oscillations is investigated and their significant influence on the secondary flow patterns in the downstream channel is revealed.

Flow Visualization of Secondary Flows in Three Curved Ducts

1986 ◽  
Author(s):  
G. M. Sanz ◽  
R. D. Flack
Keyword(s):  
Secondary Flow ◽  
Cross Sections ◽  
Flow Patterns ◽  
Secondary Flows ◽  
Radius Of Curvature ◽  
Symmetric Flow ◽  
Flow Measurements ◽  
Curved Ducts ◽  
Flow Velocities ◽  
Pressure Driven

Secondary flows were experimentally examined in three 90° curved ducts with square cross sections and different radii of curvature. Dean numbers were from 1.5 × 104 to 3.6 × 104 and radius ratios of 0.5, 2.3, and 3.0 were used. Streak photography flow measurements were made and general developing secondary flow patterns were studied for three cross sections in each bend: the inlet (0° plane), the midpoint (45° plane), and the outlet (90° plane). At the 0° plane, stress driven secondary flows were found to consist of flow toward the duct corners from the center, balanced by return flow at the side bisectors. This resulted in eight symmetric flow patterns at the inlet. After a rapid transition region, the pressure driven secondary flow patterns were found to be characterized by flow moving toward the outer curved wall at the axial midplane and returning to the inner wall along the duct walls. At the 45° and 90° planes two symmetric flow patterns were observed. Secondary flow velocities in the test elbow with the smallest radius of curvature, where centrifugal forces are greater, were as much as 27% higher than secondary flows in the more gradual turns examined in this study. Also, the pressure driven secondary flows at the exit were higher than the stress driven flows at the inlet by as much as 39%. The elbow with a radius ratio of 0.5 was found to influence the upstream inlet conditions the most and the secondary flow velocities at the inlet were as much as 56% higher than for the larger radii of curvature.

Classification of Pulsating Flow Patterns in Curved Pipes

1996 ◽  
Vol 118 (3) ◽  
pp. 311-317 ◽  
Author(s):  
Shigeru Tada ◽  
Shuzo Oshima ◽  
Ryuichiro Yamane
Keyword(s):  
Secondary Flow ◽  
Amplitude Ratio ◽  
Circular Cross Section ◽  
Volumetric Flow Rate ◽  
Flow Patterns ◽  
Womersley Number ◽  
Dean Number ◽  
Curved Pipes ◽  
Convection Dominated

The fully developed periodic laminar flow of incompressible Newtonian fluids through a pipe of circular cross section, which is coiled in a circle, was simulated numerically. The flow patterns are characterized by three parameters: the Womersley number Wo, the Dean number De, and the amplitude ratio β. The effect of these parameters on the flow was studied in the range 2.19 ≤ Wo ≤ 50.00, 15.07 ≤ De ≤ 265.49 and 0.50 ≤ β ≤ 2.00, with the curvature ratio δ fixed to be 0.05. The way the secondary flow evolved with increasing Womersley number and Dean number is explained. The secondary flow patterns are classified into three main groups: the viscosity-dominated type, the inertia-dominated type, and the convection-dominated type. It was found that when the amplitude ratio of the volumetric flow rate is equal to 1.0, four to six vortices of the secondary flow appear at high Dean numbers, and the Lyne-type flow patterns disappear at β ≥ 0.50.

Investigations of the Flow Through a High Pressure Ratio Centrifugal Impeller

2002 ◽  
Author(s):  
Gernot Eisenlohr ◽  
Hartmut Krain ◽  
Franz-Arno Richter ◽  
Valentin Tiede
Keyword(s):  
High Pressure ◽  
Flow Separation ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Centrifugal Impeller ◽  
Angle Distribution ◽  
Blade Angle ◽  
Minor Variation ◽  
Design Point ◽  
High Pressure Ratio

In an industrial research project of German and Swiss Turbo Compressor manufacturers a high pressure ratio centrifugal impeller was designed and investigated. Performance measurements and extensive laser measurements (L2F) of the flow field upstream, along the blade passage and downstream of the impeller have been carried out. In addition to that, 3D calculations have been performed, mainly for the design point. Results have been presented by Krain et al., 1995 and 1998, Eisenlohr et al., 1998 and Hah et al.,1999. During the design period of this impeller a radial blade at the inlet region was mandatory to avoid a rub at the shroud due to stress reasons. The measurements and the 3D calculations performed later, however, showed a flow separation at the hub near the leading edge due to too high incidence. Additionally a rather large exit width and a high shroud curvature near the exit caused a flow separation near the exit, which is enlarged by the radially transported wake of the already addressed hub separation. Changes to the hub blade angle distribution to reduce the hub incidence and an adaptation of the shroud blade angle distribution for the same impeller mass-flow at the design point were investigated by means of 3D calculations first with the same contours at hub and shroud; this was followed by calculations with a major change of the shroud contour including an exit width change with a minor variation of the hub contour. These calculations showed encouraging results; some of them will be presented in conjunction with the geometry data of the original impeller design.

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