一、技术规范
英菲尼迪QX60的技术规范如表1所示。表1英菲尼迪QX60的技术规范二、检查CVT油液应该在CVT油液加热到50~80℃的情况下检查液位,步骤如下。1.检查油液是否泄漏。2.在发动机暖机后,在城区驾驶汽车。当环境温度为20℃时,C V ...一、技术规范
英菲尼迪QX60的技术规范如表1所示。表1英菲尼迪QX60的技术规范二、检查CVT油液应该在CVT油液加热到50~80℃的情况下检查液位,步骤如下。1.检查油液是否泄漏。2.在发动机暖机后,在城区驾驶汽车。当环境温度为20℃时,C V T油液升温到50~80℃大约需要10分钟。展开更多
In order to study the effects of wet compression on a transonic compressor,a full 3-D steady numerical simulation was carried out under varying conditions.Different injected water flow rates and droplet diameters were...In order to study the effects of wet compression on a transonic compressor,a full 3-D steady numerical simulation was carried out under varying conditions.Different injected water flow rates and droplet diameters were considered.The effect of wet compression on the shock,separated flow,pressure ratio,and efficiency was investigated.Additionally,the effect of wet compression on the tip clearance when the compressor runs in the near-stall and stall situations was emphasized.Analysis of the results shows that the range of stable operation is extended,and that the pressure ratio and inlet air flow rate are also increased at the near-stall point.In addition,it seems that there is an optimum size of the droplet diameter.展开更多
Activities by various authors on aerodynamics and control dynamics of rotating stall in axial compressor are first traced. Then, a process of stall cell evolution in a subsonic stage is discussed based on a 2-D CFD. A...Activities by various authors on aerodynamics and control dynamics of rotating stall in axial compressor are first traced. Then, a process of stall cell evolution in a subsonic stage is discussed based on a 2-D CFD. A few numbers of vortices grow ahead of the rotor accumulating vorticity ejected from lightly stalled blades, and eventually organize a cell of circumferentially aligned huge vortices, which merge and recess repeatedly during the rotation. Such stall disturbance is intensified on trailing side of a circumferential inlet distortion and decays on the leading side. Considering these features, a new algorithm for stall warning is developed based on a correlation between pressure waveforms at each passing of a fixed blade. A remarkable change in the correlation level at near-stall provides a warning signal prior to the stall onset with sufficiently large time margin. This scheme is applied to achieve rotating stall prevention by actuating flaps installed on the hub. The last issue is on characteristics of forward swept blade which has much increased throttle margin with decreased tip loss. A 3-D computation shows that a secondary vortex generated in suction surface mid span interacts to reduce the tip leakage vortex that initiates the stall.展开更多
It is well known that tip leakage flow has a strong effect on the compressor performance and stability. This paper reports on a numerical investigation of detailed flow structures in an isolated transonic compressor r...It is well known that tip leakage flow has a strong effect on the compressor performance and stability. This paper reports on a numerical investigation of detailed flow structures in an isolated transonic compressor rotor-NASA Rotor 37 at near stall and stalled conditions aimed at improving understanding of changes in 3D tip leakage flow structures with rotating stall inception.Steady and unsteady 3D Navier-Stokes analyses were conducted to investigate flow structures in the same rotor.For steady analysis,the predicted results agree well with the experimental data for the estimation of compressor rotor global performance.For unsteady flow analysis, the unsteady flow nature caused by the breakdown of the tip leakage vortex in blade tip region in the transonic compressor rotor at near stall condition has been captured with a single blade passage.On the other hand, the time-accurate unsteady computations of multi-blade passage at near stall condition indicate that the unsteady breakdown of the tip leakage vortex triggered the short length-scale-spike type rotating stall inception at blade tip region.It was the forward spillage of the tip leakage flow at blade leading edge resulting in the spike stall inception. As the mass flow ratio is decreased,the rotating stall cell was further developed in the blade passage.展开更多
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 order to investigate the effects of probe support on the stall characteristics of micro compressors, an experiment was carried out on a large-scale low-speed research compressor according to the principle of geomet...In order to investigate the effects of probe support on the stall characteristics of micro compressors, an experiment was carried out on a large-scale low-speed research compressor according to the principle of geometric similarity. A cylindrical probe support intruding to 50% blade span was mounted at 50% chord upstream from the rotor blade leading edge. The static pressure rise characteristic of the compressor is measured, with and without the probe support respectively. The dynamic compressor behavior from pre-stall to full stall was also measured. The results indicate that the stability margin of the compressor is lowered after installing the probe support. The stall inception is aroused by modal wave disturbances. The disturbances developed into two stall cells smoothly before installing the probe support, while the disturbances first developed into a single stall cell then splitting into two stall cells after installing the probe support. The presence of probe support lowers the initial intensity of the rotating stall of the compressor, while it doesn't alter the intensity of the rotation stall after the compressor enters into full stall.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.50776021
文摘In order to study the effects of wet compression on a transonic compressor,a full 3-D steady numerical simulation was carried out under varying conditions.Different injected water flow rates and droplet diameters were considered.The effect of wet compression on the shock,separated flow,pressure ratio,and efficiency was investigated.Additionally,the effect of wet compression on the tip clearance when the compressor runs in the near-stall and stall situations was emphasized.Analysis of the results shows that the range of stable operation is extended,and that the pressure ratio and inlet air flow rate are also increased at the near-stall point.In addition,it seems that there is an optimum size of the droplet diameter.
文摘Activities by various authors on aerodynamics and control dynamics of rotating stall in axial compressor are first traced. Then, a process of stall cell evolution in a subsonic stage is discussed based on a 2-D CFD. A few numbers of vortices grow ahead of the rotor accumulating vorticity ejected from lightly stalled blades, and eventually organize a cell of circumferentially aligned huge vortices, which merge and recess repeatedly during the rotation. Such stall disturbance is intensified on trailing side of a circumferential inlet distortion and decays on the leading side. Considering these features, a new algorithm for stall warning is developed based on a correlation between pressure waveforms at each passing of a fixed blade. A remarkable change in the correlation level at near-stall provides a warning signal prior to the stall onset with sufficiently large time margin. This scheme is applied to achieve rotating stall prevention by actuating flaps installed on the hub. The last issue is on characteristics of forward swept blade which has much increased throttle margin with decreased tip loss. A 3-D computation shows that a secondary vortex generated in suction surface mid span interacts to reduce the tip leakage vortex that initiates the stall.
基金National Natural Science Foundation of China(Project No:50806073)
文摘It is well known that tip leakage flow has a strong effect on the compressor performance and stability. This paper reports on a numerical investigation of detailed flow structures in an isolated transonic compressor rotor-NASA Rotor 37 at near stall and stalled conditions aimed at improving understanding of changes in 3D tip leakage flow structures with rotating stall inception.Steady and unsteady 3D Navier-Stokes analyses were conducted to investigate flow structures in the same rotor.For steady analysis,the predicted results agree well with the experimental data for the estimation of compressor rotor global performance.For unsteady flow analysis, the unsteady flow nature caused by the breakdown of the tip leakage vortex in blade tip region in the transonic compressor rotor at near stall condition has been captured with a single blade passage.On the other hand, the time-accurate unsteady computations of multi-blade passage at near stall condition indicate that the unsteady breakdown of the tip leakage vortex triggered the short length-scale-spike type rotating stall inception at blade tip region.It was the forward spillage of the tip leakage flow at blade leading edge resulting in the spike stall inception. As the mass flow ratio is decreased,the rotating stall cell was further developed in the blade passage.
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.
基金funded by the National Natural Science Foundation of China(Grant No.51161130525 and 51136003)the 111 Project,No.B07009
文摘In order to investigate the effects of probe support on the stall characteristics of micro compressors, an experiment was carried out on a large-scale low-speed research compressor according to the principle of geometric similarity. A cylindrical probe support intruding to 50% blade span was mounted at 50% chord upstream from the rotor blade leading edge. The static pressure rise characteristic of the compressor is measured, with and without the probe support respectively. The dynamic compressor behavior from pre-stall to full stall was also measured. The results indicate that the stability margin of the compressor is lowered after installing the probe support. The stall inception is aroused by modal wave disturbances. The disturbances developed into two stall cells smoothly before installing the probe support, while the disturbances first developed into a single stall cell then splitting into two stall cells after installing the probe support. The presence of probe support lowers the initial intensity of the rotating stall of the compressor, while it doesn't alter the intensity of the rotation stall after the compressor enters into full stall.
