15th European Conference on Turbomachinery Fluid dynamics & Thermodynamics

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Radial Compressors



Emma Johanna Adam  - TU Bergakademie Freiberg, Germany
Martin Heinrich - TU Bergakademie Freiberg, Germany
Rüdiger Schwarze - TU Bergakademie Freiberg, Germany


The geometric dimensions of a compressor have great influence on the performance of the machine. Regenerative compressors are a kind of turbomachine that have a found a wide range of application in the industry. However, the influence of the geometric parameters on the characteristic curve have not yet been fully explored. Regenerative compressors consist of a static part, composed of the side channel, the inlet and outlet port which are separated by the stripper and a rotating part, the impeller. The factors with significant influence on the side channel compressors performance in the static domain are the side channel height and its form (like round or square), the decrease of the side channel area in direction of rotation, the length of the stripper and the placement of the inlet and outlet ports. In this work the focus is on three factors that determine the side channel. These are the side channel height at the inlet, the change of the side channel area in direction of rotation and the angle of the stripper. These factors are chosen because they are expected to highly interact with one another in their influence on the flow in the side channel. To evaluate the influence of the factors on the performance, a design of experiment approach is employed. The three factors are tested in an full factorial design plan. The factors are tested on two stages, employing a linear model for the description of the influence. For the chosen factors these stages are a channel height equaling the length of the blades and a channel height shorther than the blades. The side channel area is not changed for one stage. For the second stage the area of the side channel is halved from inlet to outlet. The stripper extends over either three or or six blades. With the use of a full factorial design it is possible to make out the interactions of the factors and their influence on the effects. The non-linearity of the responses is not expected to be as big as the interactions between the factors. With the results it is possible to not only understand the influence of the tested factors on the total pressure ratio and the isentropic efficiency of the regenerative compressor, but for the first time also estimate how the geometric parameters interact and how they can improve the machines performance even further when matched optimally with one another. All the investigations are conducted numerically with the open source CFD library OpenFOAM.


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