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Optimization of the pitch curve of screw vacuum pumps

Title: Optimization of the pitch curve of screw vacuum pumps
Subject: Construction of an optimized rotor geometry of screw vacuum pumps regarding the energetic efficiency.


Screw vacuum pumps are widely used as fore-vacuum pumps in different applications. The main advantage compared to rotary vane pumps is the oil-free working chamber. Increasing possibilities in production techniques have led to the use of rotors with a variable pitch to realize an internal compression and has become a standard in industrial applications.


Within the scope of this project an investigation of the influence of a variable pitch regarding the thermodynamical operation behaviour is carried out. An opimized layout of a screw vacuum pump under consideration of geometrical and operational parameters represents the aim of this project. A rotor geometry has to be developed, which possesses energetic beneficial characteristics considering the operation behaviour. The approach uses current research results of the chair of fluidics, where an evolutionary optimization procedure is used. The pitch curve is varried for fixed geometric parameters, like the crown and root circle, rotor length, rotational speed and suction pressure, to determine an optimized geometry. The delivered mass flow and the needed inner power serve as evaluation criterions for the calculated geometries. According to the evolutionary approach geometries are elected under consideration of the named criterions. Further on these geometries are varied respectively combined to determine pareto-optimized solutions iteratively. The result is a so called Pareto-Front, where every point represents a pareto-optimized geometry (see Fig. 1). Fig 2 shows an exemplary rotor geometry optimized with the described approach.


Pareto_Optimierung_english Zusammenbau_Opti_8000
Fig. 1: Pareto-optimized solutions of the rotor geometry for different iteration steps. Fig. 2: Exemplary, pareto-optimized rotor geometry



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Univ. Prof. Dr.-Ing. Andreas Brümmer
Tel.: 0231 755-5720
Timo Jünemann, M.Sc.
Tel.: 0231 755-5784