scholarly journals A novel design on smooth rotor profile with meshing clearance for screw vacuum pump

2022 ◽  
Vol 14 (1) ◽  
pp. 168781402110704
Author(s):  
Li Zhang ◽  
Yang Liu ◽  
Yongju Zhang ◽  
Ziyun Chen
Keyword(s):  
Transient Flow ◽  
Vacuum Pump ◽  
Radial Clearance ◽  
Ansys Fluent ◽  
Rotor Profile ◽  
Offset Distance ◽  
Section Profile ◽  
Cross Section Profile ◽  
Pump Cavity ◽  
Novel Design

Cross-section profile of rotor takes a great effect on the performance of dry-screw vacuum pump. A novel smooth rotor profile consisting of eight segments of curves, including arcs and conjugate correction curves is proposed. Advantages are that it can be used to solve the unsmooth connection and no meshing clearance in traditional profile. The meshing model for new profile can directly generate stable addendum clearance, tooth clearance, tooth side clearance, and radial clearance. The influences of the epicycloid rotation angle, arc radius and involute offset distance of the conjugate correction curve on the clearances are studied according to established theoretical model. And transient flow field of vacuum pump is analyzed by using the commercial software Ansys-Fluent®. Compared to traditional screw vacuum pump, the results shows that pressure in inlet and pump cavity is lower, and maximum pumping speed is higher, indicating that the proposed design is superior.

scholarly journals Effects of stable clearances on backflow in the variable-pitch screw vacuum pump

2021 ◽  
Vol 22 ◽  
pp. 46
Author(s):  
Li Zhang ◽  
Yongju Zhang ◽  
Ziyun Chen
Keyword(s):  
Three Dimensional ◽  
Internal Flow ◽  
Calculation Model ◽  
Vacuum Pump ◽  
Three Dimensional Model ◽  
Ansys Fluent ◽  
Variable Pitch ◽  
Rotating Speed ◽  
Tooth Surfaces ◽  
Pump Cavity

Effects of various clearances of variable-pitch screw vacuum pump on gas backflow of internal flow field of the pump cavity is studied. The theoretical tooth surfaces of screw rotor are optimized by radial, normal equidistance modifications, and four types of stable clearances of rotor circumferential, radial, tooth shape and tooth sides are obtained. The backflow calculation model in clearances considering Couette backflow and orifice backflow is improved. The three-dimensional model of variable-pitch screw vacuum pump is designed, and the experimental prototype and test device are developed. The internal backflow of vacuum pump is analyzed by using the commercial software Ansys-Fluent® and the calculation model. The results show that the smaller the clearances, the smaller the backflow and the higher the vacuum degree. Among the four types of clearances, the circumferential clearance plays the primary roles. The backflow is directly proportional to the inlet pressure and rotating speed. Predictions are validated by the experimental data with satisfied agreement.

scholarly journals INFLUENCE OF LASER BEAM PROFILE ON LIGHT SCATTERING BY HUMAN SKIN DURING PHOTOMETRY BY ELLIPSOIDAL REFLECTORS

2018 ◽  
Vol 9 (1) ◽  
pp. 56-65 ◽  
Author(s):  
M. A. Bezuglyi ◽  
N. V. Bezuglaya ◽  
S. Kostuk
Keyword(s):  
Monte Carlo Simulation ◽  
Adipose Tissue ◽  
Laser Beam ◽  
Human Skin ◽  
Cross Section ◽  
Beam Profile ◽  
Laser Beam Profile ◽  
Reflected Light ◽  
Section Profile ◽  
Cross Section Profile

The correct accounting of laser emitter parameters for improvement of diagnostic authenticity of methods of optical biomedical diagnostic is important problem for applied biophotonic tasks. The purpose of the current research is estimation of influence of energy distribution profile in transversal section of laser beam on light scattering by human skin layers at photometry by ellipsoidal reflectors.Biomedical photometer with ellipsoidal reflectors for investigation of biological tissue specimens in transmitted and reflected light uses laser probing radiation with infinitely thin, Gauss-type and uniform cross-section profile. Distribution of beams with denoted profiles, which consist of 20 million photons with wavelength 632.8 nm, was modeled by using of Monte-Carlo simulation in human skin layers (corneous layer, epidermis, derma and adipose tissue) of various anatomic thickness and with ellipsoidal reflectors with focal parameter equal to 16.875 mm and eccentricity of 0.66.The modeling results represent that illuminance distribution in zones of photometric imaging is significantly influenced by the laser beam cross-section profile for various thickness of corneous layer and epidermis in transmitted and reflected light, and also derma in reflected light. Illuminance distribution for adipose tissue in reflected and transmitted light, and also derma in transmitted light, practically do not depend of laser beam profile for anatomic thicknesses, which are appropriate for human skin on various sections of body.There are represented results of modified Monte-Carlo simulation method for biomedical photometer with ellipsoidal reflectors during biometry of human skin layers. For highly scattered corneous layer and epidermis the illumination of middle and external rings of photometric images changes depending from the laser beam profile for more than 50 % in transmitted and 30 % in reflected light. For weakly scattering skin layers (derma and adipose layer) the influence of profile can be observed only for derma in reflected layer and is equal not more than 15 %. 

scholarly journals Fusion17 summary talk: windsurfing on a cross section profile

2017 ◽  
Vol 163 ◽  
pp. 00067
Author(s):  
Dieter Ackermann ◽  
Lorenzo Corradi
Keyword(s):  
Cross Section ◽  
Section Profile ◽  
Cross Section Profile ◽  
Summary Talk

On the Cross-Section Structure of the Mitochondrial Cristae-Membrane as Revealed by X-Ray Diffraction

1976 ◽  
Vol 31 (9-10) ◽  
pp. 612-621 ◽  
Author(s):  
W Müller-Klieser ◽  
W Kreutz
Keyword(s):  
Cross Section ◽  
Function Evaluation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Section Profile ◽  
The Cross ◽  
Diffraction Patterns ◽  
Cross Section Profile ◽  
Section Structure ◽  
Q Function

Abstract Mitochondria were isolated using sorbitol and high buffer concentration in the medium. X-ray diffraction patterns arising from the mitochondrial cristae-membrane were recorded in the fully dried state and in two different states in humidity. The Q-function evaluation of these X-ray dif­fraction diagrams resulted in electron density cross-section profiles, which consist of two main peaks of opposite sign and one, respectively two, smaller peaks. The total thickness of the membrane amounts to 120 Å in the dry and 140 Å to 160 Å in the wet state.An interpretation of the cross-section profile is tentatively proposed.

Profiling Rotors for Limaçon-to-Limaçon Compression-Expansion Machines

2005 ◽  
Vol 128 (4) ◽  
pp. 787-793 ◽  
Author(s):  
Ibrahim A. Sultan
Keyword(s):  
Nonlinear Equations ◽  
Volumetric Efficiency ◽  
Radial Clearance ◽  
A Value ◽  
First Case ◽  
Rotor Profile ◽  
Mathematical Expressions ◽  
Second Mode ◽  
Extreme Care

Limaçon-to-limaçon compression-expansion machines have housings and rotors whose profiles are manufactured of limaçon curves. For these machines to perform satisfactorily, extreme care should be given to the geometric particulars of their rotor profile. The main characteristics that govern the quality of the rotor profile are the volumetric efficiency and the prevention of interference. In this work, the interference problem is handled from two different mathematical standpoints: the slope of tangents to both the rotor and housing curves at the apices; and the value of the minimum radial clearance that separates the two limaçon curves. In the first case, mathematical expressions, relating the radii of the limaçon base circles is presented to ensure that interference would not take place during normal operations of the limaçon-to-limaçon machine. The second mode of analysis produces a set of nonlinear equations that can be solved to obtain a value of the radial clearance. This value has to be machined off the rotor profile to prevent interference. A numerical example is given at the end of the paper to prove the validity of the models proposed and graphs are produced to support the claims presented.

Optimization of cold formed steel cross section profile for timber upgrading

2012 ◽  
Author(s):  
C. González-Bravo ◽  
J. Claver ◽  
R. Alvarez ◽  
R. Domingo
Keyword(s):  
Cross Section ◽  
Section Profile ◽  
Cold Formed Steel ◽  
Cross Section Profile

Design constraints of five-arc Roots vacuum pumps

2002 ◽  
Vol 216 (2) ◽  
pp. 225-234 ◽  
Author(s):  
P-Y Wang ◽  
Z-H Fong ◽  
H S Fang
Keyword(s):  
Design Procedure ◽  
Vacuum Pump ◽  
Tooth Profile ◽  
Design Constraints ◽  
Circular Arc ◽  
Ultimate Pressure ◽  
Rotor Profile ◽  
Circular Arcs ◽  
Centre Of Rotation ◽  
Inlet Opening

The design constraints for the tooth profile of the five-arc Roots vacuum pump are derived and discussed in this paper. The addendum portion of the five-arc tooth profile comprises five smoothly connected circular arcs, while the dedendum portion consists of conjugate curves of the addendum portion of the mating rotor. The top land of the proposed rotor profile is a circular arc with its centre coinciding with the centre of rotation. Therefore, the gap between the top land of the rotor and the wall of the chamber turns into a long and narrow path, which provides better gas sealing and wider inlet opening. The design constraints of the rotor profile are quite complex owing to the limitations of zero carryover and the condition of non-undercutting. A design procedure is proposed for determining the feasible design region by considering the geometry constraints, zero carryover and non-undercutting. By using the proposed procedure, wider inlet opening and better gas sealing are expected, while the characteristic of zero carryover is maintained. The results of experiment show that the ultimate pressure of the prototype of the five-arc Roots vacuum pump is 2,5 × 10-3 torr, and the maximum pumping speed is 1600L/min. The performance of the prototype is excellent compared with commercially available mechanical dry vacuum pumps.

Theoretical and Experimental Vibration Analyses of Trapezoidal and Sinusoidal Corrugated Plates

2012 ◽  
Author(s):  
Adil Yucel ◽  
Alaeddin Arpaci
Keyword(s):  
Cross Section ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Analysis Technique ◽  
Surface Models ◽  
Section Profile ◽  
Corrugated Plates ◽  
Cross Section Profile ◽  
Manufacturing Parameters ◽  
Theoretical Results

In this study, dynamic behaviour of trapezoidal and sinusoidal corrugated plates which are widely used in the fields of space, aviation, automotive, construction and shipbuilding have been analyzed. 330 different surface models varying according to corrugation height and number have been created for these plates which have various manufacturing parameters. At this stage, the number of analyses is 660. These models have been analyzed for different boundary conditions and modal analyses to obtain natural frequencies and mode shapes have been conducted using finite element method. In addition, changes in the trapezoidal cross-section profile have also been investigated by analyzing 38 different plates with varying cross-section profiles. Examining these results, the effects of corrugation height and number on natural frequencies and mode shapes have been determined. As a result of the study a total of 368 drawings were prepared and 736 analyses were performed. Besides, the theoretical results have been verified using the experimental modal analysis technique for some selected models which are being manufactured in the market.

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