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 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.

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.

Evaluating the Interlobe Clearance and Determining the Sizes and Shapes of All the Leakage Paths for Twin-Screw Vacuum Pump

2006 ◽  
Vol 220 (4) ◽  
pp. 499-506 ◽  
Author(s):  
Z H Fong ◽  
F C Huang
Keyword(s):  
Cross Section ◽  
Vacuum Pump ◽  
Contact Pattern ◽  
Minimum Cross Section ◽  
Exact Evaluation ◽  
Twin Screw ◽  
Red Lead ◽  
Rotor Profiles ◽  
Screw Rotors ◽  
Cross Section Method

The maximum sphere method and the minimum cross-section method are proposed to calculate the interlobe clearance between two mating screw rotors and to determine the shapes and sizes of all the leakage paths. These two methods are inspired by the red-lead and tooth-contact pattern and can be used to evaluate the interlobe leakage and to design the mating rotor profiles. The combined results of these two methods provide the basis for an exact evaluation of the fluid leakage, and this feature increases flexibility in geometrical designing and manufacturing of the screw rotors. These methods are also suitable for non-conjugate rotors and contribute to thermal analysis and optimum programming.

scholarly journals A Novel Rotor Profile Error Tracing and Compensation Strategy for High Precision Machining of Screw Rotor Based on Trial Cutting of Limited Samples

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
ZhiHuang Shen ◽  
Bin Yao ◽  
BinQiang Chen ◽  
Wei Feng ◽  
XiangLei Zhang
Keyword(s):  
Machine Tool ◽  
High Precision ◽  
Error Compensation ◽  
Precision Machining ◽  
Limited Sample ◽  
Rotor Profile ◽  
Screw Rotor ◽  
Novel Method ◽  
Error Tracing ◽  
Screw Rotors

The machining precision plays an important role in the operation reliability and service life of screw rotors. However, the actual machined rotor profile of screw rotors is different from its theoretical profile due to the errors of the machine tool. This paper proposes a novel method of error tracing and compensation to reduce the machined errors of rotor profile on the basis of the limited sample trials, and the method is based on a matrix of error compensation. The errors of rotor profile are obtained based on limited sample trials machining of screw rotors,and fitted into piecewise smooth data. A matrix of error compensation is established to compute the errors of rotor profile to generate a compensated rotor profile. The compensated rotor profile is then used to regenerate forming tool and a new rotor product is processed on the same machine tool. And the errors of new rotor profile are smaller and can be reduced within (−0.01 mm, 0.01 mm) after compensations. Finally, the actual machining examples illustrate that the method of error compensation can not only satisfy the machining requirement of high-precision rotors, but also has the characteristics of good stability and applicability.

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.

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.

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