Screw Rotor Profiles of Variable Lead Vacuum and Multiphase Machines and Their Calculation Models

2016 ◽  
Author(s):  
Nikola Stosic ◽  
Sham Rane ◽  
Ahmed Kovacevic ◽  
Ian K. Smith
Keyword(s):  
Manufacturing Cost ◽  
Twin Screw ◽  
Wrap Angle ◽  
Screw Rotor ◽  
Rotor Profiles ◽  
Calculation Models ◽  
Moving Parts

Twin screw machines are mechanically simple and reliable, having only two moving parts, while their manufacturing cost is low and, as a result of optimization of their rotor proportions and profiles, their efficiency is high. Consequently, they are now used widely both as multiphase and vacuum pumps. This study gives the results of an investigation of how their performance is affected by changing the rotor lead, i.e. the axial step along the rotor wrap, from a constant value to a variable one. A number of different configurations have been considered and it is shown that, for machines with a large wrap angle, a variable lead results in greater displacement and improved efficiency.

Synthesis and Optimization for Rotor Profiles in Twin Rotor Screw Compressors

1998 ◽  
Vol 122 (4) ◽  
pp. 543-552 ◽  
Author(s):  
Shyh-Haur Su ◽  
Ching-Huan Tseng
Keyword(s):  
Contact Line ◽  
Optimization Problems ◽  
Synthesis Method ◽  
Line Length ◽  
Contact Lines ◽  
Rotor Profile ◽  
Twin Screw ◽  
Screw Rotor ◽  
Rotor Profiles ◽  
Parameter Values

This paper proposes a systematic synthesis method for twin-screw rotor profiles for compressors. Both “original generating curves” and “generated curves” are distributed on each rotor profile, and all the geometric parameters of these curves can be determined with satisfying the conditions of continuity in tangency by given only several specific parameter values. The contact lines on rotor surfaces and the blowhole area calculation are also presented. Three cases of optimization problems are shown in this paper and both contact-line length and blowhole area are reduced when letting the contact-line length be the object function with a constraint of blowhole area. [S1050-0472(00)01103-X]

Rotor Profile Design for the Twin-Screw Compressor Based on the Normal-Rack Generation Method

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Yu-Ren Wu ◽  
Zhang-Hua Fong
Keyword(s):  
Helix Angle ◽  
Tooth Profile ◽  
Normal System ◽  
Rotor Profile ◽  
Twin Screw ◽  
Screw Rotor ◽  
Profile Design ◽  
Rotor Tooth ◽  
Rotor Profiles ◽  
Screw Rotors

This paper proposes a method for designing the rotor profiles of twin-screw compressors using a rack defined in the normal plane. All tooth profile segments are explicitly defined as tangent continuous in the normal section to generate a pair of conjugated rotors. Numerical comparisons between the two types of screw rotor tooth profile design, one based on a normal system, the other on an axial system, show the advantages of using the normal-rack generation method (NRGM). Most particularly, this method allows the same hob used for screw rotors to be used to manufacture mating rotors even as the helix angle varies, because in a normal system the circular pitch remains the same. The numerical results also indicate that the rotor tooth thickness generated by the NRGM rack cutter can prevent serious deflection for a variety of helix angles and tooth combinations.

scholarly journals Study on the reverse design of screw rotor profiles based on a B-spline curve

2019 ◽  
Vol 11 (10) ◽  
pp. 168781401988378 ◽  
Author(s):  
Shu Cao ◽  
Xueming He ◽  
Rong Zhang ◽  
Junfeng Xiao ◽  
Guojiang Shi
Keyword(s):  
Fluid Dynamics ◽  
Fluid Simulation ◽  
Screw Compressor ◽  
B Spline ◽  
Spline Curve ◽  
Rotor Profile ◽  
Twin Screw ◽  
Screw Rotor ◽  
Profile Design ◽  
Rotor Profiles

The female/male screw rotor profile design for a twin screw compressor poses challenges such as frequent parameter modification and a difficult-to-build performance test platform, which affect the efficiency of a rotor profile design. To address these problems, a new idea of applying a B-spline curve to a twin screw compressor rotor profile design is proposed in this article. In addition, the design result underwent fluid simulation based on fluid dynamics technology. This method overcomes the aforementioned challenges. As a meshing line has one-to-one mapping relationship with the rotor profile and reflects important performance parameters of the rotor profile, the method of deducing female and male rotor profiles for a twin screw compressor from a meshing line is proposed. Furthermore, the B-spline curve is used as a composition curve of the meshing line to achieve fast local adjustment of the rotor tooth profile. Based on existing rotor profiles, a meshing line is designed via the B-spline curve, and female and male rotor profiles are derived in reverse. The final rotor profile underwent fluid simulation via computational fluid dynamics analysis under various conditions to analyze the pattern of the internal flow field, which is compared with the results from conventional design.

Inter-lobe clearance estimation for twin-screw rotor pairs with point-meshing features

2020 ◽  
pp. 095440892097139
Author(s):  
Minh-Thuận Hoàng ◽  
Yu-Ren Wu
Keyword(s):  
Cad Model ◽  
Screw Pump ◽  
Pump Performance ◽  
Leakage Path ◽  
Rotor Profile ◽  
Shortest Distance ◽  
Twin Screw ◽  
Screw Rotor ◽  
Rotor Profiles ◽  
Solution Accuracy

In practical production, it is impossible even to measure the inter-lobe (meshing) clearance of a screw rotor pair. However, understanding of the clearance distribution is essential since it is a major leakage path which greatly affects the twin-screw pump performance. Previous publications did not disclose explicit detail on how to calculate the meshing clearance for screw rotor pairs with point-meshing features. Therefore, this study proposes a meshing clearance calculation method for screw rotor pairs with point-meshing features. The complex meshing clearance can be simply determined by calculating the shortest distance between two normal-rack profiles generated using point-enveloping principle. Clearance distributions are much more intelligible to be exhibited on a 3-D contact line and the rotor profile. Due to its immeasurability in practice, the adaptability and the solution accuracy of the proposed numerical method are verified by applications on different rotor profiles and comparisons with measured results from a 3-D CAD model. The meshing clearance in a variable-pitch screw rotor pair and the clearance adjustability are also illustrated through the proposed examples.

Development and Optimization of Screw Machines With a Simulation Model—Part I: Profile Generation

1997 ◽  
Vol 119 (3) ◽  
pp. 659-663 ◽  
Author(s):  
N. Stosˇic´ ◽  
K. Hanjalic´
Keyword(s):  
Conjugacy Condition ◽  
Positive Displacement ◽  
Rotor Profile ◽  
Twin Screw ◽  
Compression And Expansion ◽  
Screw Rotor ◽  
Differential Algorithm ◽  
Rotor Profiles ◽  
Generation Procedure ◽  
Thermodynamic Processes

This paper presents a method for the design of twin screw compressors and expanders, which is based on a differential algorithm for defining the rotor profiles and an analytical model of the fluid flow and thermodynamic processes within the machine. Part I of the paper describes the algorithm for screw rotor profile generation. It demonstrates the conjugacy condition which, when solved explicitly, enables a variety of primary arcs to be defined either analytically or by discrete point curves. Its use greatly simplifies the design since only primary arcs need to be specified and these can be located on either the main or gate rotor or even on any other rotor including a rack, which is a rotor of infinite radius. Secondary arcs are then generated automatically from this. By such means any profile combination may be considered. The most efficient were obtained from a combined rotor-rack generation procedure. An example of this combination is given which produces a rotor profile with stiff lobes and a higher throughput than any other known type. Part II describes a mathematical model of the compression and expansion processes within positive displacement machines which has been well proven in its use for the design of reciprocating and screw compressors and screw expanders.

A Numerical Contour Method for Simulating Spiral Groove Bottom Profiles

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Weifeng Wu ◽  
Shuo Sun ◽  
Quanke Feng
Keyword(s):  
Surface Profile ◽  
Contour Method ◽  
Contact Lines ◽  
Spiral Groove ◽  
Groove Surface ◽  
Contact Points ◽  
Envelope Method ◽  
Twin Screw ◽  
Rotor Profiles ◽  
Boundary Contact

The envelope method can be used to model the spiral groove surface profile in single screw compressors produced by cylindrical milling using the contact lines of the cutter surface and the groove. However, the envelope method cannot predict the groove bottom profile accurately because it does not account for the boundary contact lines on the end face of the cutter. A new numerical contour method is proposed to model the groove bottom profile by identifying the contact points on the end face of the cutter to a set position on the spiral groove. Results show that the new method can calculate accurately both the boundary and the inner contact line and thus simulate the groove bottom profile exactly. This method could also be used to simulate other profiles of machines, such as rotor profiles of twin screw compressors and screw pumps.

Study of a screw rotor with different stocks and leads for a twin-screw multiphase pump

2009 ◽  
Vol 223 (11) ◽  
pp. 2637-2645 ◽  
Author(s):  
F Cao ◽  
T Gao ◽  
J Jiao ◽  
T Pan ◽  
Z Xing
Keyword(s):  
Dominant Role ◽  
Contour Plot ◽  
Leakage Flow ◽  
Normal Height ◽  
Plot Analysis ◽  
Rotor Profile ◽  
Twin Screw ◽  
Screw Rotor ◽  
Flow Through ◽  
Multi Phase

Rotor profile generation and geometry characteristics play a dominant role in developing twin-screw multi-phase pumps. The aim of this work is to present mathematical procedures to calculate screw rotor profile generation, design rotor cutter tools, and rotor geometry characteristics with given stocks for twin-screw multi-phase pumps. Analyses of the profile generation of a screw rotor for a multi-phase pump are carried out. The resulting rotor profile with different stocks is developed on the basis of the calculation of the forming cutter tool profile. An iso-height contour plot is presented for describing the shape and size of the overlapped cavity of the rotors. By inspecting the iso-height contour plot, analysis of all the possible leakage flow through the inter-lobe clearance is performed. According to the iso-height contour plot, the blowhole provides the major leakage path for the basic chambers through the overlapped cavity. The minimum normal height of the overlapped cavity has a linear relationship with the stock. The larger stocks lead to greater leakage and reduce pump performance. The leakage flow through the overlapped cavity will be aggravated and the performance of the twin-screw multi-phase pump will decline with the increasing lead of the screw rotor.

Virtual Design and Structural Optimization of Dry Twin Screw Vacuum Pump with a New Rotor Profile

2009 ◽  
Vol 16-19 ◽  
pp. 1392-1396 ◽  
Author(s):  
Shi Wei Zhang ◽  
Zhi Jun Zhang ◽  
Cheng Hai Xu
Keyword(s):  
Structural Optimization ◽  
Three Dimensional ◽  
Vacuum Pump ◽  
Vacuum System ◽  
Virtual Design ◽  
Three Dimensional Modeling ◽  
Rotor Profile ◽  
Twin Screw ◽  
Screw Rotor ◽  
Involute Curve

Twin screw vacuum pump is an important kind of dry vacuum pump, which is widely used in the oil-free vacuum system. The design of the screw rotor profile directly influences the working performance and manufacture cost of the screw pumps. In this paper, a new rotor profile for twin screw vacuum pump is introduced which is comprised of the cycloid curve, the dedendum circle arc, the involute curve and the addendum circle arc. The processes of three-dimensional modeling, motion simulation, interference checking and structural optimization for twin screw vacuum pumps are studied by means of Solidworks software. The works provide theoretical basis for optimal designing and reference for test prototype manufacturing. The results showed the performance of the vacuum pump according with the designer’s intention.

Fabrication and Microstructural Analysis of CNTs Reinforced Copper Matrix Nanocomposites via MIM Technique

2013 ◽  
Vol 459 ◽  
pp. 11-17 ◽  
Author(s):  
Ali Samer Muhsan ◽  
Faiz Ahmad ◽  
Norani M. Mohamed ◽  
Muhammad Rafi Raza Malik
Keyword(s):  
Carbon Nanotubes ◽  
Injection Molding ◽  
Microstructural Analysis ◽  
Copper Matrix ◽  
Metal Injection Molding ◽  
Solid Loading ◽  
Twin Screw ◽  
Viscous Media ◽  
Screw Rotor ◽  
Matrix Nanocomposites

Carbon nanotubes (CNTs) reinforced copper (Cu) matrix nanocomposites prepared via advanced fabrication method is presented. Functionalization and ultrasonication processes have been applied to enhance the dispersion of purified CNTs and creates sidewalls groups that have the potential to bond CNTs to the metal matrix. The main part of this approach was metal injection molding (MIM) technique, which is a combination of powder metallurgy and plastic injection molding technique. Preparation of MIM feedstock required a melting and mixing process of binder system (polymers) with the solid loading, which has been carried out using a twin screw rotor machine. This machine provides a viscous media of the molten binder with high shear forces that allow the additives (carbon nanotubes/copper powder) to be mixed properly and exfoliate the CNTs clusters with uniformdispersion inside the Cu matrix. Subsequently, to prove our expected results, observation tests of TEM, SEM, FESEM and CNTS were employed and discussed literally.

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