scholarly journals A geometric study of different curves for the rotor profiles of a twin-screw compressor

2021 ◽  
Vol 312 ◽  
pp. 11001
Author(s):  
Antonio Giuffrida
Keyword(s):  
Straight Line Segment ◽  
Base Case ◽  
Conic Sections ◽  
Current Case ◽  
Rotor Profile ◽  
Straight Line ◽  
Twin Screw ◽  
Rotor Profiles ◽  
Geometric Study

This paper presents the results of comparisons among some patented solutions for profiling the contours of the rotors in twin-screw compressors. Referring to a base case where all the generating curves are circumferences, patents suggesting to replace arcs of circumference with arcs of conic sections, i.e. parabola, ellipse and hyperbola, but even a straight line segment, are presented and guidelines for rotor profile construction are reported. After setting the size of the compressor, attention is paid to the inter-lobe area, as the sum of the area between two consecutive lobes in the male rotor and of the area of the groove in the female rotor. Actually, this area is strictly related to the volume displacement. Limited to the current case study, the profile including an elliptic segment seems to be the preferable solution for higher inter-lobe area, then for higher displacement, though a number of considerations should be necessary for a broader context.

scholarly journals A Novel Engagement-Pixel Tracking Method for Meshing Clearance Layout of Twin-Screw Rotors

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Jie Lu ◽  
Zhiqin Cai ◽  
Sijie Cai ◽  
Bin Yao ◽  
Binqiang Chen
Keyword(s):  
Normal Vector ◽  
Discrete Point ◽  
Tracking Method ◽  
Rotor Profile ◽  
Twin Screw ◽  
Contact Models ◽  
Novel Method ◽  
Rotor Profiles ◽  
Screw Rotors

The performance of dry twin-screw compressors is primarily affected by the meshing clearance between a pair of meshing rotors. In this paper, a novel method for meshing clearance layout (MCL) is presented. The presented method is based on the engagement-pixel tracking (EPT) technique, which utilizes discrete-pixel curves generated by the two rotors. An algorithm for the proposed method is put forward. Firstly, when the profile of one rotor is known, the discrete point coordinates of the two rotor profiles and their thermal expansion profiles can be obtained. Secondly, the instantaneous contact models of the two rotors at special meshing positions are acquired under pixel coordinate system. Thirdly, through inspecting the pixels on the profile of a rotor and establishing the corresponding normal vector, the meshing clearance of the two rotors is extracted. Then, the meshing clearances can be generated by extracting the boundary pixels on the other rotor profile. Finally, the meshing clearance layout method is proposed. To verify the effectiveness of the presented method, a case study was conducted on a pair of meshing rotors to extract its meshing clearance. It was shown that the proposed method can be used as a tool for evaluating the clearance distribution of actual machined profiles.

scholarly journals Rotor profile design and numerical analysis of 2–3 type multiphase twin-screw pumps

2017 ◽  
Vol 232 (2) ◽  
pp. 186-202 ◽  
Author(s):  
Di Yan ◽  
Qian Tang ◽  
Ahmed Kovacevic ◽  
Sham Rane ◽  
Linqing Pei
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Performance ◽  
Oil And Gas ◽  
Advantages And Disadvantages ◽  
Rotor Profile ◽  
Computational Fluid Dynamics Analysis ◽  
Performance Curves ◽  
Twin Screw ◽  
Rotor Profiles

Increasing demands for high-performance handling of fluids in oil and gas as well as other applications require improvements of efficiency and reliability of screw pumps. Rotor profile plays the key role in the performance of such machines. This paper analyses difference in performance of 2–3 lobe combination of twin-screw pumps with different rotor profiles. A-type profile formed of involute–cycloid curves and D-type formed of cycloid curves are typical representatives for 2–3 type screw pumps. The investigation is performed by use of a full 3-D computational fluid dynamics analysis based on a single-domain structured moving mesh obtained by novel grid generation procedure. The real-time mass flow rate, rotor torque, pressure distribution and velocity field were obtained from 3D computational fluid dynamics calculations. The performance curves were produced for variable rotation speeds and variable discharge pressures. The computational fluid dynamics model was validated by comparing the simulation results of the A-type pump with the experimental data. In order to get the performance characteristics of D-type profile, two rotors with D-type profile were designed. The first has the same displacement volume as A-type while the second has the same lead and rotor length as A-type but different displacement volume. The comparison of results obtained with two rotor profiles gave an insight on the advantages and disadvantages of each of them.

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 Generation Method for Twin Screw Compressors Based on Bi-Direction

2012 ◽  
Vol 229-231 ◽  
pp. 465-469
Author(s):  
Xue Ming He ◽  
Ming Han ◽  
Yang Deng ◽  
Yi Lu ◽  
Chen Liang Hua
Keyword(s):  
New Method ◽  
Reverse Direction ◽  
Screw Compressor ◽  
Key Technology ◽  
Rotor Profile ◽  
Twin Screw ◽  
Rotor Profiles

The performance of twin-screw compressor is mainly decided by profiles of the two rotors. The constitution of new rotor profiles is studied, meanwhile the key technology of generating rotor profiles are mainly studied in this paper. A new method based on forward and reverse direction for generating rotor profiles with meshing lines is proposed.

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 Leadership Approach for the New Millennium: A Case Study of UCLA's Bruin Leaders Project

NASPA Journal ◽  
2001 ◽  
Vol 38 (2) ◽  
Author(s):  
Charles L. Outcalt ◽  
Shannon K. Faris ◽  
Kathleen N. McMahon ◽  
Philip M. Tahtakran ◽  
Christopher B. Noll
Keyword(s):  
Social Development ◽  
Student Development ◽  
Research University ◽  
Leadership Theory ◽  
Public Research ◽  
Current Case ◽  
Leadership Model ◽  
Public Research University ◽  
New Millennium

The current case study investigates the application of a non-hierarchical leadership model at an urban public research university. Following a review of recent contributions to leadership theory, especially with regard to student development, the authors balance discussions of the values on which the program under review is based with descriptions of the practical structure of the program. In addition, they suggest means by which other campuses can tailor this program to their resources, opportunities, and needs. The case study concludes with a discussion of the program’s effect on students’ cognitive and social development.

Integral Modeling of a Twin-Screw Compressor

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Sarah Van Erdeweghe ◽  
Joris De Schutter ◽  
Eric Van den Bulck
Keyword(s):  
Working Conditions ◽  
Control Volume ◽  
Optimization Procedure ◽  
Future Research ◽  
Screw Compressor ◽  
Positive Displacement ◽  
Rotor Profile ◽  
Twin Screw ◽  
Large Application ◽  
Similarity Law

In this paper, an integral methodology for the modeling of a twin-screw compressor is presented. Starting from a known rotor profile, all the algorithms to calculate the second rotor profile, the size of the control volume, and the compressor's performance are presented. The proposed modeling approach can be applied in an optimization procedure to find the optimal rotor profiles for a given application, with corresponding working conditions. Furthermore, based on the modeling results and substantiated with measurements on different compressor types, a similarity law for positive displacement compressors seems to exist. The existence of a similarity law has large application potential as it could be used to predict the performance of a positive displacement compressor in other than the (lab) tested working conditions. Further investigation of the similarity law for positive displacement compressors is therefore proposed as a key topic for future research.

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