Effects of Leaning and Curving of Blades With High Turning Angles on the Aerodynamic Characteristics of Turbine Rectangular Cascades

1994 ◽  
Vol 116 (3) ◽  
pp. 417-424 ◽  
Author(s):  
Han Wanjin ◽  
Wang Zhongqi ◽  
Tan Chunqing ◽  
Shi Hong ◽  
Zhou Mochun
Keyword(s):  
Flow Field ◽  
Aerodynamic Characteristics ◽  
Acute Angle ◽  
Obtuse Angle ◽  
Bubble Flow ◽  
Helium Bubble ◽  
Negatively Curved ◽  
Horseshoe Vortices ◽  
Logical Result

To understand the effects of the origination and development of centralized vortices on the aerodynamic characteristics of turbine rectangular cascades with high turning angles, experiments with five-hole microspherical probes, accompanied by color helium bubble flow displays, were carried out. The measurement planes are arranged as three before, six in, and one after the cascade. The experiments reveal that the origination and development of horseshoe vortices and passage vortices as well as the interaction of the latters almost dominate the whole flow field of traditional linear cascades. Lean linear cascades favor the horseshoe vortices and passage vortices in the acute angle zone, and impede those in the obtuse angle zone. So it is a logical result to adopt the negatively curved blades, whose pressure surfaces and both endwalls compose both obtuse angles, respectively, to improve the cascade aerodynamic characteristics.

scholarly journals Effects of Leaning and Curving of Blades With High Turning Angles on the Aerodynamic Characteristics of Turbine Rectangular Cascades

1993 ◽  
Author(s):  
Wanjin Han ◽  
Chunqing Tan ◽  
Hong Shi ◽  
Mochun Zhou ◽  
Zhongqi Wang
Keyword(s):  
Flow Field ◽  
Aerodynamic Characteristics ◽  
Acute Angle ◽  
Obtuse Angle ◽  
Bubble Flow ◽  
Helium Bubble ◽  
Negatively Curved ◽  
Horseshoe Vortices ◽  
Logical Result

To intensively understand the effects of the origination and development of centralized vortices on the aerodynamic characteristics of turbine rectangular cascades with high turning angles, an experiments with 5-hole micro spherical probes, accompanied by color helium bubble flow display, were carried out. The measurement planes are arranged as 3 before, 6 in and 1 after, the cascade. The experiments reveal that the origination and development of horseshoe vortices and passage vortices as well as the interaction of the latters almost dominate the whole flow field of traditional linear cascades. Lean linear cascades favor the horseshoe vortices and passage vortices in the acute angle zone, and impede those in the obtuse angle zone. So it is a logical result to adopt the negatively curved blades, whose pressure surfaces and both endwalls compose both obtuse angles respectively, to improve the cascade aerodynamic characteristics.

Endothelial nitric oxide synthase (eNOS) mediates neointimal thickness in arteriovenous fistulae with different anastomotic angles in rats

2021 ◽  
pp. 112972982199653
Author(s):  
Hualong Bai ◽  
Shunbo Wei ◽  
Boao Xie ◽  
Zhiwei Wang ◽  
Mingxing Li ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Nitric Oxide Synthase ◽  
Neointimal Hyperplasia ◽  
Acute Angle ◽  
Obtuse Angle ◽  
Enos Expression ◽  
Arteriovenous Fistulae ◽  
Neointimal Thickness ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Background: It is known that the anastomotic angle can influence neointimal hyperplasia and patency in arteriovenous fistulae (AVF). Endothelial nitric oxide synthase (eNOS) is released from the vascular endothelium and can inhibit neointimal hyperplasia. Therefore, here, we aimed to test the hypothesis that the manipulation of eNOS expression could influence neointimal thickness in a rat AVF model with different anastomosis angles. Methods: Rat carotid artery (inflow, CA) and jugular vein (outflow, JV) AVF were created with acute, blunt, or end-to-end (ETE) anastomosis angles. Aspirin was used to increase eNOS expression in the acute angle group, while N(G)-nitro-L-arginine methyl ester (L-name) was used to decrease eNOS expression in the obtuse angle group. The rats were sacrificed on day 21, and tissues were harvested and analyzed histologically and with immunostaining. Results: A larger anastomosis diameter ( p < 0.016) and smaller neointimal area ( p < 0.01) were observed in the obtuse and end-to-end (ETE) groups compared to in the acute group. In the acute angle group, there were more proliferating cell nuclear antigen (PCNA) and α-actin dual-positive cells ( p < 0.0001) and fewer phospho (p)-eNOS-positive endothelial cells ( p < 0.0001) in the neointima than in the obtuse and ETE angle groups. On treating the acute angle and blunt angle groups with aspirin and L-name, respectively, no significant differences in the neointima/lumen rate were observed ( p = 0.6526) between the groups; however, there were fewer von Willebrand factor (vWF) and p-eNOS dual-positive cells in the obtuse angle group treated with L-name ( p = 0.0045). Conclusions: We demonstrated that eNOS plays an important role in neointimal hyperplasia in AVF with different anastomosis angles; further, eNOS could potentially be used as a therapeutic target in patients with AVF in the future.

scholarly journals Rhombus and Rhomboid Parallelogram Patterns on Glaciers: Natural Indicators of Strain

1979 ◽  
Vol 22 (87) ◽  
pp. 247-261 ◽  
Author(s):  
Charles J. Waag ◽  
Keith Echelmeyer
Keyword(s):  
Strain Rate ◽  
Flow Direction ◽  
Acute Angle ◽  
Principal Strain ◽  
Obtuse Angle ◽  
Strain Rates ◽  
Ice Flow ◽  
Glacier System ◽  
Glacier Ice

AbstractSubtle rhombus and rhomboid parallelogram patterns occur on Vaughan Lewis Glacier and the Gilkey Glacier System, Juneau Icefield, Alaska. The patterns are within the firn at the firn-ice interface, are formed by differential recrystallization within narrow preferred zones, and are apparently manifestations of stresses transferred upward from the glacier ice. On the glaciers of the Gilkey System the patterns occur where intense lateral shortening is indicated by abrupt convergence of medial moraines and an abundance of extension crevasses. The short axes of the rhombi and the obtuse angle bisectors of the rhomboids are subparallel to the strike of extension crevasses, therefore to the axis of shortening. The long axes of the rhombi and the acute angle bisectors of the rhomboids are parallel to the foliation, and ice-flow direction. The angles of the parallelograms are variable locally, but average 105° and 75°; the variation seems to reflect intensity and duration of stress. Similar parallelograms occur within the troughs of wave bulges below the Vaughan Lewis Icefall. In the wave bulges, the foliation arcs parallel the wave. The long axes of the rhombi and acute angle bisectors of the rhomboids parallel the foliation around the foliation arc. The short axes of the rhombi and the obtuse angle bisectors of the rhomboids parallel the strikes of radial crevasses, are perpendicular to the direction of extension, and form a fan divergent down-stream. The precise mechanisms and conditions of formation of the parallelograms are not yet understood. Preliminary strain-rate measurements suggest, however, that correlations exist between the orientations of the principal strain-rates and the axes of the patterns, and between the magnitude of the strain-rates and the axial lengths of the patterns.

A Method for Aerodynamic Characteristic Analysis of Hypersonic Aircraft Based on Response Surface Model

2013 ◽  
Vol 477-478 ◽  
pp. 277-280 ◽  
Author(s):  
Jie Yang ◽  
Song Ping Wu ◽  
Wen Xin Hou
Keyword(s):  
Flow Field ◽  
Response Surface ◽  
Aerodynamic Characteristic ◽  
Aerodynamic Characteristics ◽  
Surface Model ◽  
Complex Flow ◽  
Characteristic Analysis ◽  
Response Surface Models ◽  
Hypersonic Aircraft ◽  
Surface Models

Aerodynamic characteristic analysis of hypersonic cruise aircraft is more difficult than that of conventional aircraft, for the complex flow field simulation and inadequate amount of results under limited flight conditions. In this paper, numerical schemes applicable for hypersonic flow field are adopted to acquire a set of aerodynamic characteristics of a typical hypersonic cruise aircraft as sample data, based on which response surface models (RSM) are constructed to provide approximation of aerodynamic characteristics under any flight conditions within the design domain, finally the overall approximation performance of the response surface models are analyzed.

scholarly journals Numerical Simulation and Analysis of External Flow Field of the Van

2019 ◽  
Vol 293 ◽  
pp. 01001
Author(s):  
Kan Zhou ◽  
Ge Huang ◽  
Bin Liu ◽  
Qi Hu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Vortex Motion ◽  
Aerodynamic Characteristics ◽  
External Flow ◽  
Calculation Results

This paper uses CFD preprocessing software to build Van model and gridding it, then CFD software is used to simulation the outflow field of Van model, from which the distribution of pressure and velocity is obtained and the outflow field is analyzed. The calculation results indeed reflect the aerodynamic characteristics of the external flow field of the van, and the flow movement on the van surface is better simulated. In addition, the positions where the vortex motion is relatively severe are also found

scholarly journals The hexahydrated double selenates containing thallium. Completion of the thallium salts and of the whole monoclinic series

1928 ◽  
Vol 118 (780) ◽  
pp. 393-426 ◽  
Keyword(s):  
Ferrous Iron ◽  
Preceding Paper ◽  
Acute Angle ◽  
Obtuse Angle ◽  
Density Measurements ◽  
Cobalt Nickel ◽  
Nickel Cobalt ◽  
Volume Properties ◽  
Iron Nickel ◽  
First Time

The introduction to the preceding memoir (p. 367) applies equally to this paper, in which are described the six double selenates containing thallium as the R-metal and magnesium, ferrous iron, nickel, cobalt, manganese, and copper as the M-metal respectively. The optical and volume properties and constants of the zinc-thallium selenate are also included, as these were not determinable with the crystals described in 1909, while lately the author has obtained quite excellent crystals of this salt suitable for all purposes. While this work has been in progress a paper by L. C. Lindsley and L. M. Dennis has appeared, concerning five of these thallium double selenates, those in which the M-metal is copper, cobalt, nickel, magnesium, and manganese, which they consider to have made for the first time. This is, of course, an error, as all of them were made by the author previous to 1909, as will be clear from p. 367 of the preceding paper; but, as there stated, the crystals obtained were not of adequate perfection for complete goniometrical, optical and density measurements and determinations. Lindsley and Dennis, however, only give measurements of two angles, and these are supplementary to each other, being the acute and obtuse angles of the primary prism p {110}. They give no optical or other physical data. They found in the case of each salt an increase of about 40' in the acute angle of the prism, and a like amount of diminution of the supplementary obtuse angle, compared with the corresponding angle on the crystals of the analogous double sulphate.

Are the Obtuse Angles the Key Components of the Poggendorff Illusion?

Perception ◽  
1981 ◽  
Vol 10 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Peter Wenderoth ◽  
Michael Johnson
Keyword(s):  
Poggendorff Illusion ◽  
Acute Angle ◽  
Obtuse Angle ◽  
Negative Effects ◽  
Linear Summation ◽  
Displacement Effect ◽  
Positive Effects ◽  
Poggendorff Figure

An experiment is reported which confirms and extends a previous finding that amputations of the Poggendorff figure do not necessarily result in large positive effects with obtuse-angle stimuli, and small or even negative effects with acute-angle stimuli. Indeed, the acute-angle effects found were significantly greater than the obtuse-angle effects, and the full Poggendorff error was not explicable in terms of the linear summation of the component-angle effects. An ‘alignment displacement effect’ reported earlier by Hotopf and Obonai was shown to occur, but could not be an important component of the Poggendorff illusion.

Research of Lane-Changed Overtaking Based on Overlapping Grid

2012 ◽  
Vol 209-211 ◽  
pp. 2100-2103 ◽  
Author(s):  
Jing Yu Wang ◽  
Xing Jun Hu ◽  
Zhi Zhang
Keyword(s):  
Flow Field ◽  
Theoretical Foundation ◽  
Aerodynamic Characteristics ◽  
Side Force

Based on overlapping grid, two cars were simulated when lane-changed overtaking and the aerodynamic characteristics of two cars were achieved. By analysis the coefficients of side force and yawing moment and flow field around two cars when two cars’ position changed the flow motivation and rules of interference each other were researched. The conclusions can provide the theoretical foundation for the research of transient overtaking.

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