scholarly journals Highly Deforming Computational Meshes for CFD Analysis of Twin-Screw Positive Displacement Machines

2018 ◽  
Author(s):  
Sham Rane ◽  
Ahmed Kovačević ◽  
Nikola Stošić ◽  
Ian Smith
Keyword(s):  
Cfd Analysis ◽  
Positive Displacement ◽  
Twin Screw

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.

scholarly journals CFD Simulations of Single- and Twin-Screw Machines with OpenFOAM

Designs ◽  
2020 ◽  
Vol 4 (1) ◽  
pp. 2
Author(s):  
Nicola Casari ◽  
Ettore Fadiga ◽  
Michele Pinelli ◽  
Alessio Suman ◽  
Davide Ziviani
Keyword(s):  
Vapor Compression ◽  
Single Screw ◽  
Positive Displacement ◽  
Cfd Models ◽  
Equation Of States ◽  
Screw Machine ◽  
Twin Screw ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Analyses ◽  
Dynamic Meshing

Over the last decade, Computational Fluid Dynamics (CFD) has been increasingly applied for the design and analysis of positive displacement machines employed in vapor compression and power generation applications. Particularly, single-screw and twin-screw machines have received attention from the researchers, leading to the development and application of increasingly efficient techniques for their numerical simulation. Modeling the operation of such machines including the dynamics of the compression (or expansion) process and the deforming working chambers is particularly challenging. The relative motion of the rotors and the variation of the gaps during machine operation are a few of the major numerical challenges towards the implementation of reliable CFD models. Moreover, evaluating the thermophysical properties of real gases represents an additional challenge to be addressed. Special care must be given to defining equation of states or generating tables and computing the thermodynamic properties. Among several CFD suite available, the open-source OpenFOAM tool OpenFOAM, is regarded as a reliable and accurate software for carrying out CFD analyses. In this paper, the dynamic meshing techniques available within the software as well as new libraries implemented for expanding the functionalities of the software are presented. The simulation of both a single-screw and a twin-screw machine is described and results are discussed. Specifically, for the single-screw expander case, the geometry will be released as open-access for the entire community. Besides, the real gas modeling possibilities implemented in the software will be described and the CoolProp thermophysical library integration will be presented.

Positive Displacement Gear Lube Pump CFD Analysis

2021 ◽  
Author(s):  
Srinivas Goud Goda ◽  
Mukesh Kumar ◽  
Vitthal K. Khandagale ◽  
Leons Antony Lawrence
Keyword(s):  
Cfd Analysis ◽  
Positive Displacement

A Study on the Influence of the Suction Arrangement on the Performance of Twin Screw Compressors

2013 ◽  
Author(s):  
Maria Pascu ◽  
Manoj Heiyanthuduwage ◽  
Sebastien Mounoury ◽  
Graeme Cook ◽  
Ahmed Kovacevic
Keyword(s):  
Screw Compressor ◽  
Complex Flow ◽  
Positive Displacement ◽  
Complex Shapes ◽  
Twin Screw ◽  
Profiling Techniques ◽  
Compressor Performance ◽  
Manufacturing Tolerances ◽  
Area Of Concern ◽  
Angle Of Rotation

Screw compressors are complex flow systems, but operate upon simple considerations: they are positive displacement machines consisting of meshing rotors contained in a casing to form a working chamber, whose volume depends only on the angle of rotation. Their performance is highly affected by leakages, which is dependent on various clearances and the pressure differences across these clearances. Nowadays, the manufacturing and profiling techniques have matured so much, that rotors of even the most complex shapes can be manufactured to tolerances in the order of few microns, resulting in high efficiencies. With manufacturing tolerances this tight, there is only small amount of improvement expected from further exploration of this venue, and a rather different direction for analysis may be more rewarding, i.e. other components of the screw compressor, like the suction and discharge areas. While the available literature includes several references on improvements of the compressor performance based on the analysis of the discharge port and discharge chamber, the investigation of the suction arrangement and inlet port remains fairly unexplored. This is the area of concern for the present paper, where the influence of the port shape and suction arrangement on the overall compressor performance is investigated. Two suction models were investigated for a standard screw compressor by means of CFD, which allowed in-depth analyses and flow visualizations, confirmed by the experimental investigation carried out on the actual compressor.

scholarly journals 3D CFD analysis of a twin screw expander

2013 ◽  
pp. 417-429 ◽  
Author(s):  
A. Kovacevic ◽  
S. Rane
Keyword(s):  
Cfd Analysis ◽  
Twin Screw

scholarly journals New insights in twin screw expander performance for small scale ORC systems from 3D CFD analysis

2015 ◽  
Vol 91 ◽  
pp. 535-546 ◽  
Author(s):  
Iva Papes ◽  
Joris Degroote ◽  
Jan Vierendeels
Keyword(s):  
Small Scale ◽  
Cfd Analysis ◽  
Twin Screw

scholarly journals Bi-Directional System Coupling for Conjugate Heat Transfer and Variable Leakage Gap CFD Analysis of Twin-Screw Compressors

2021 ◽  
Vol 1180 (1) ◽  
pp. 012001
Author(s):  
S Rane ◽  
A Kovačević ◽  
N Stošić ◽  
I K Smith
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Cfd Analysis ◽  
Twin Screw ◽  
System Coupling

scholarly journals The Influence of Rotor Geometry on Power Transfer Between Rotors in Gerotor-Type Screw Compressors

2019 ◽  
Vol 142 (7) ◽  
Author(s):  
Matthew G. Read ◽  
Nikola Stosic ◽  
Ian K. Smith
Keyword(s):  
Performance Indicators ◽  
Input Power ◽  
Power Transfer ◽  
Multi Objective Optimization ◽  
Positive Displacement ◽  
Rotor Profile ◽  
Outer Rotor ◽  
Twin Screw ◽  
Wrap Angle ◽  
Swept Volume

Abstract The configuration of a twin-screw positive displacement machine is proposed, consisting of an internally geared outer rotor meshing with an externally geared inner rotor. Helical rotors with constant profile and pitch are used with parallel rotor axes and stationary end plates incorporating inlet and discharge ports to achieve internal compression or expansion. The focus of this paper is to understand the effect of rotor geometry on two key performance indicators; the swept volume of the machine and the proportion of input power transferred between the inner and outer rotors. This requires a detailed analysis of the limitations on rotor profile generation, the formation of working chambers, and the forces exerted on the rotors. The choice of the rotor for power transfer to or from the machine is shown to be an important consideration, and helical rotors are found to enable lower power transfer between rotors during operation when compared with straight-cut rotors, but with reduced swept volume for the same machine size. For particular applications, this compromise is characterized through multi-objective optimization of the rotor profile and wrap angle in order to identify appropriate configurations for the proposed machine.

Numerical Analysis for Twin Screw Pump Internal Flow

2011 ◽  
Vol 130-134 ◽  
pp. 3658-3663
Author(s):  
Qian Tang ◽  
Abebe Misganaw ◽  
Xian Zhi Ye ◽  
Yuan Xun Zhang
Keyword(s):  
Control Volume ◽  
Flow Analysis ◽  
Internal Flow ◽  
Numerical Control ◽  
Screw Pump ◽  
Steady State Condition ◽  
Various Boundary Conditions ◽  
Positive Displacement ◽  
Twin Screw ◽  
Displacement Pump

Screw pump is a special type of rotary positive displacement pump in which the flow through the pumping elements is truly axial. The objective of this study is to develop a numerical solution method for flow analysis of a twin screw pump by using a Single Rotating Reference Frame method with various boundary conditions and rotational speeds of rotor on steady state condition. Flow variable contours and plots were obtained for fluid flow inside a pump subject to pressure inlet and pressure outlet conditions using the numerical control volume method in the commercial package of FLUENT. This work needs for the analysis of flow parameters inside a screw pump in order to achieve optimum design.

Vibration Modeling and Experimental Results of Two Phase Flow Twin-Screw Pump

2015 ◽  
Author(s):  
Ameen R. A. Muhammed ◽  
Dara W. Childs
Keyword(s):  
Critical Speed ◽  
Dynamic Pressure ◽  
Excitation Frequency ◽  
Harmonic Excitation ◽  
Running Speed ◽  
Two Phase ◽  
Screw Pump ◽  
Positive Displacement ◽  
Twin Screw ◽  
Dynamic Pressure Measurements

In turbomachines, the transfer of energy between the rotor and the fluid does not — in theory — result in lateral forces on the rotor. In positive displacement machines, on the other hand, the transfer of energy between the moving and stationary components usually results in unbalanced pressure fields and forces. In [1] the authors developed a model to predict the dynamic forces in twin screw pumps, showing that the helical screw shape generates hydraulic forces that oscillate at multiples of running speed. The work presented here attempts to validate the model in [1] using a clear-casing twin screw pump. The pump runs in both single and multiphase conditions with exit pressure up to 300 KPa and a flow rate 0.6 liter per second. The pump was instrumented with dynamic pressure probes across the axial length of the screw in two perpendicular directions to validate the dynamic model. Two proximity probes measured the dynamic rotor displacement at the outlet to validate the rotordynamics model and the hydrodynamic cyclic forces predicted in [1]. The predictions were found in good agreement with the measurements. The amplitude of the dynamic pressure measurements in two perpendicular plans supported the main assumptions of the model (constant pressure inside the chambers and linear pressure drop across the screw lands). The predicted rotor orbits at the pump outlet in the middle of the rotor matched the experimental orbits closely. The spectrum of the response showed harmonics of the running speed as predicted by the model. The pump rotor’s calculated critical speed was at 24.8 krpm, roughly 14 times the rotor’s running speed of 1750 rpm. The measured and observed excitation frequencies extended out to nine times running speed, still well below the 1st critical speed. However, for longer twin-screw pumps running at higher speed, the coincidence of a higher-harmonic excitation frequency with the lightly damped 1st critical speed should be considered.

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