Active magnetic bearings present unique capabilities compared to other bearing systems, allowing their use in a range of challenging environments and applications. This paper reviews these unique capabilities, which c...Active magnetic bearings present unique capabilities compared to other bearing systems, allowing their use in a range of challenging environments and applications. This paper reviews these unique capabilities, which can be broadly categorized as: elimination of wear; elimination of sealing and lubrication systems; reduction or elimination of transmitted noise and force; use as instrumentation systems; and thermal capabilities. When combined, these capabilities can provide high reliability and availability in challenging applications. The paper goes on to consider how a challenging application or environment may affect the design of a magnetic bearing system and the use of these capabilities. Examples of such applications within the author's own company are presented together with a brief review of some of the available literature.展开更多
The suction muffler of hermetic reciprocating compressors is installed in order to attenuate the noise generated by the gas pulsation of the flow through the suction valve. However, the installation of the suction muf...The suction muffler of hermetic reciprocating compressors is installed in order to attenuate the noise generated by the gas pulsation of the flow through the suction valve. However, the installation of the suction muffler affects the operation of the compressor owing to gas pressure drop, which causes volumetric and energetic efficiency loss due to the gas specific volume augmentation. Therefore, there is a compromise between sound attenuation and pressure drop increase, which has to be taken into account by compressor designers. In this work, it presents a numerical solution to the flow through a suction muffler in order to analyze the pressure field and point out the main contributions to the overall pressure drop of the flow. A commercial CFD （computational fluid dynamics） code was used to perform the numerical simulations and the results were validated by using experimental data. After analyzing the pressure field, the geometry of the muffler was modified intending to decrease the flow pressure drop. The geometric modification produced a 28% reduction on the overall pressure drop, without influencing the sound attenuation.展开更多
文摘Active magnetic bearings present unique capabilities compared to other bearing systems, allowing their use in a range of challenging environments and applications. This paper reviews these unique capabilities, which can be broadly categorized as: elimination of wear; elimination of sealing and lubrication systems; reduction or elimination of transmitted noise and force; use as instrumentation systems; and thermal capabilities. When combined, these capabilities can provide high reliability and availability in challenging applications. The paper goes on to consider how a challenging application or environment may affect the design of a magnetic bearing system and the use of these capabilities. Examples of such applications within the author's own company are presented together with a brief review of some of the available literature.
文摘The suction muffler of hermetic reciprocating compressors is installed in order to attenuate the noise generated by the gas pulsation of the flow through the suction valve. However, the installation of the suction muffler affects the operation of the compressor owing to gas pressure drop, which causes volumetric and energetic efficiency loss due to the gas specific volume augmentation. Therefore, there is a compromise between sound attenuation and pressure drop increase, which has to be taken into account by compressor designers. In this work, it presents a numerical solution to the flow through a suction muffler in order to analyze the pressure field and point out the main contributions to the overall pressure drop of the flow. A commercial CFD （computational fluid dynamics） code was used to perform the numerical simulations and the results were validated by using experimental data. After analyzing the pressure field, the geometry of the muffler was modified intending to decrease the flow pressure drop. The geometric modification produced a 28% reduction on the overall pressure drop, without influencing the sound attenuation.
