Steady discrete micro air injection at the tip region in front of the first compressor rotor has been proved to be an effective method to delay the inception of rotating stall in a low speed axial compressor. Consider...Steady discrete micro air injection at the tip region in front of the first compressor rotor has been proved to be an effective method to delay the inception of rotating stall in a low speed axial compressor. Considering the practical application a new type of micro injector was designed and described in this paper, which was imbedded in the casing and could be moved along the chord. In order to verify its feasibility to other cases, such as high subsonic axial compressor or centrifugal compressor, some other cases have been studied. Experimental results of the same low speed axial compressor showed that the new injector could possess many other advantages besides successfully stabilizing the compressor. Experiments performed on a high subsonic axial compressor confirmed the effectiveness of micro air injection when the relative velocity at the blade tip is high subsonic. Meanwhile in order to explore its feasibility in centrifugal compressor, a similar micro injector was designed and tested on a low speed centrifugal compressor with vaned diffuser. The injected mass flow was a bit larger than that used in axial compressors and the results showed micro injection could also delay the onset of rotating stall in the centrifugal compressor.展开更多
In the recent past, experimental studies have shown some advantages of blade lean and sweep in axial compressors. As most of the experimental results are combined with other features, it is difficult to determine the ...In the recent past, experimental studies have shown some advantages of blade lean and sweep in axial compressors. As most of the experimental results are combined with other features, it is difficult to determine the effect of individual parameters on the performance of the compressor. The present numerical studies are aimed at understanding the performance and three-dimensional flow pattern at the exit of swept and unswept rotors. Three rotors, namely; unswept, 200 forward swept and 200 backward swept rotors are analysed with a specific intention of understanding the pattern of the blade boundary layer flow. The analysis was done using a fully three-dimensional viscous CFD code CFX-5. Results indicated reduction in pressure rise with sweep. Backward sweep is detrimental as far as the performance near endwalls is considered. On the other hand total pressure loss in the wake in mid span region is less with backward sweep, which favours its application here. However, backward sweep adversely affects the stall margin. The ability of the forward sweep to deflect the streamlines towards hub gets diminished at low flow rates. Forward sweep changes the streamline pattern in such a way that the suction surface streamlines are deflected towards the hub and the pressure surface streamlines are deflected towards the easing. An opposite behaviour is observed in backward swept rotors.展开更多
This research investigates the use of single dielectric barrier discharge(SDBD) actuators for energizing the tip leakage flow to suppress rotating stall inception and extend the stable operating range of a low speed a...This research investigates the use of single dielectric barrier discharge(SDBD) actuators for energizing the tip leakage flow to suppress rotating stall inception and extend the stable operating range of a low speed axial compressor with a single rotor.The jet induced by the plasma actuator adds momentum to the flow in the tip region and has a significant impact on the tip-gap flow.Experiments are carried out on a low speed axial compressor with a single rotor.The static pressure is measured at both the rotor inlet and outlet.The flow coefficient and pressure rise coefficient are calculated.Then the characteristic line is acquired to show the overall performance of the compressor.With unsteady plasma actuation of 18kV and 60W the compressor stability range improvement is realized at rotor speed of 1500 r/min – 2400 r/min.展开更多
This paper presents the investigation of the effects of suction side squealer tip on the performance of an axial compressor. The experiment is carded out in a single-stage large-scale low-speed compressor. The investi...This paper presents the investigation of the effects of suction side squealer tip on the performance of an axial compressor. The experiment is carded out in a single-stage large-scale low-speed compressor. The investigated tip geometries include fiat tip as the baseline and suction side squealer tip. The tip clearance of the baseline is 0.5% of the blade span. The static pressure rise characteristic curves of both the rotor and the stage are measured. The flow field at the exit of the rotor is measured by a 5-hole probe under design and off-design conditions. The static pressure on the endwall of the rotor passage is also obtained. The results show that the pressure rise characteristic curves obtained by measuring the pressure on the end wall are almost unchanged by using the suction side squealer tip. The measuring results of the 5-hole probe show the static pressure and the total pressure in tip region is slightly greater than that of the flat tip at the design condition at the exit of the rotor. It also leads to greater averaged static pressure rise and total pressure. At the near stall condition, the averaged static pressure and total pressure is lower than the baseline which is related to the redistribution of the blade load caused by the suction side squealer tip.展开更多
基金National Natural Science Foundation of China with project No.50676094.
文摘Steady discrete micro air injection at the tip region in front of the first compressor rotor has been proved to be an effective method to delay the inception of rotating stall in a low speed axial compressor. Considering the practical application a new type of micro injector was designed and described in this paper, which was imbedded in the casing and could be moved along the chord. In order to verify its feasibility to other cases, such as high subsonic axial compressor or centrifugal compressor, some other cases have been studied. Experimental results of the same low speed axial compressor showed that the new injector could possess many other advantages besides successfully stabilizing the compressor. Experiments performed on a high subsonic axial compressor confirmed the effectiveness of micro air injection when the relative velocity at the blade tip is high subsonic. Meanwhile in order to explore its feasibility in centrifugal compressor, a similar micro injector was designed and tested on a low speed centrifugal compressor with vaned diffuser. The injected mass flow was a bit larger than that used in axial compressors and the results showed micro injection could also delay the onset of rotating stall in the centrifugal compressor.
文摘In the recent past, experimental studies have shown some advantages of blade lean and sweep in axial compressors. As most of the experimental results are combined with other features, it is difficult to determine the effect of individual parameters on the performance of the compressor. The present numerical studies are aimed at understanding the performance and three-dimensional flow pattern at the exit of swept and unswept rotors. Three rotors, namely; unswept, 200 forward swept and 200 backward swept rotors are analysed with a specific intention of understanding the pattern of the blade boundary layer flow. The analysis was done using a fully three-dimensional viscous CFD code CFX-5. Results indicated reduction in pressure rise with sweep. Backward sweep is detrimental as far as the performance near endwalls is considered. On the other hand total pressure loss in the wake in mid span region is less with backward sweep, which favours its application here. However, backward sweep adversely affects the stall margin. The ability of the forward sweep to deflect the streamlines towards hub gets diminished at low flow rates. Forward sweep changes the streamline pattern in such a way that the suction surface streamlines are deflected towards the hub and the pressure surface streamlines are deflected towards the easing. An opposite behaviour is observed in backward swept rotors.
基金supported by the National Natural Science Foundation of China,project No.50906085International S&T Cooperation Program of China,project No.2013DFR61080
文摘This research investigates the use of single dielectric barrier discharge(SDBD) actuators for energizing the tip leakage flow to suppress rotating stall inception and extend the stable operating range of a low speed axial compressor with a single rotor.The jet induced by the plasma actuator adds momentum to the flow in the tip region and has a significant impact on the tip-gap flow.Experiments are carried out on a low speed axial compressor with a single rotor.The static pressure is measured at both the rotor inlet and outlet.The flow coefficient and pressure rise coefficient are calculated.Then the characteristic line is acquired to show the overall performance of the compressor.With unsteady plasma actuation of 18kV and 60W the compressor stability range improvement is realized at rotor speed of 1500 r/min – 2400 r/min.
基金funded by the National Natural Science Foundation of China,Grant No.51161130525 and 51136003supported by the 111 Project,No.B07009
文摘This paper presents the investigation of the effects of suction side squealer tip on the performance of an axial compressor. The experiment is carded out in a single-stage large-scale low-speed compressor. The investigated tip geometries include fiat tip as the baseline and suction side squealer tip. The tip clearance of the baseline is 0.5% of the blade span. The static pressure rise characteristic curves of both the rotor and the stage are measured. The flow field at the exit of the rotor is measured by a 5-hole probe under design and off-design conditions. The static pressure on the endwall of the rotor passage is also obtained. The results show that the pressure rise characteristic curves obtained by measuring the pressure on the end wall are almost unchanged by using the suction side squealer tip. The measuring results of the 5-hole probe show the static pressure and the total pressure in tip region is slightly greater than that of the flat tip at the design condition at the exit of the rotor. It also leads to greater averaged static pressure rise and total pressure. At the near stall condition, the averaged static pressure and total pressure is lower than the baseline which is related to the redistribution of the blade load caused by the suction side squealer tip.
