Valeo, involved in engine cooling fan system design for many years, is interested in noise prediction tools for axial fans. Thus, this paper describes a two-part study of tonal noise computation. The first part deals ...Valeo, involved in engine cooling fan system design for many years, is interested in noise prediction tools for axial fans. Thus, this paper describes a two-part study of tonal noise computation. The first part deals with the prediction of tonal noise using analytical models. As for the second part, it describes a hybrid approach for predicting tonal noise where the sources are extracted from an Unsteady Reynolds-Averaged Naviers-Stocks （URANS） simulation and then propagated into the far, free field using the Ffowcs Williams and Hawkings＇ acoustic analogy. The computational domain is meshed with 46 million polyhedral elements and the simulation takes into account the exact geometry of the rotor blades, the stator blades and the shroud. The results from the first part show that analytical models can be used for comparisons between different fan geometries, but are unable to provide accurate noise predictions compared to experimental results. The simulation shows non-periodic blade loading over a whole fan revolution, and different blade loading between the blades. This introduces some bias in the assessment of the acoustic performance of the fan. Overall, the results from the hybrid method are in accordance with the experimental results.展开更多
A Stirling-type pulse tube cryocooler （PTC） with precooling was designed and manufactured to investigate its performance at 4 K. Numerical simulation was carried out based on the well-known regenerator model REGEN w...A Stirling-type pulse tube cryocooler （PTC） with precooling was designed and manufactured to investigate its performance at 4 K. Numerical simulation was carried out based on the well-known regenerator model REGEN with an emphasis on the performance of a 4 K stage regenerator of the Stifling-type PTC as influenced by the warm end temperature, pressure ratio, frequency and average pressure with helium-4 and helium-3 as the working fluid respectively. This study demonstrates that the use of a cold inertance tube can significantly improve the efficiency of a 4 K Stirling-type PTC. A preliminary experimental investigation was carried out with helium-4 as the working fluid and a refrigeration temperature of 4.23 K was achieved. The experimental results show that the operating frequency has a significant influence on the performance of the Stirling-type PTC and a relatively low average pressure is favorable for decreasing the loss associated with the real gas effects of a 4 K Stirling-type PTC.展开更多
文摘Valeo, involved in engine cooling fan system design for many years, is interested in noise prediction tools for axial fans. Thus, this paper describes a two-part study of tonal noise computation. The first part deals with the prediction of tonal noise using analytical models. As for the second part, it describes a hybrid approach for predicting tonal noise where the sources are extracted from an Unsteady Reynolds-Averaged Naviers-Stocks （URANS） simulation and then propagated into the far, free field using the Ffowcs Williams and Hawkings＇ acoustic analogy. The computational domain is meshed with 46 million polyhedral elements and the simulation takes into account the exact geometry of the rotor blades, the stator blades and the shroud. The results from the first part show that analytical models can be used for comparisons between different fan geometries, but are unable to provide accurate noise predictions compared to experimental results. The simulation shows non-periodic blade loading over a whole fan revolution, and different blade loading between the blades. This introduces some bias in the assessment of the acoustic performance of the fan. Overall, the results from the hybrid method are in accordance with the experimental results.
基金Project (No. 50676081) supported by the National Natural Science Foundation of China
文摘A Stirling-type pulse tube cryocooler （PTC） with precooling was designed and manufactured to investigate its performance at 4 K. Numerical simulation was carried out based on the well-known regenerator model REGEN with an emphasis on the performance of a 4 K stage regenerator of the Stifling-type PTC as influenced by the warm end temperature, pressure ratio, frequency and average pressure with helium-4 and helium-3 as the working fluid respectively. This study demonstrates that the use of a cold inertance tube can significantly improve the efficiency of a 4 K Stirling-type PTC. A preliminary experimental investigation was carried out with helium-4 as the working fluid and a refrigeration temperature of 4.23 K was achieved. The experimental results show that the operating frequency has a significant influence on the performance of the Stirling-type PTC and a relatively low average pressure is favorable for decreasing the loss associated with the real gas effects of a 4 K Stirling-type PTC.
