The impact of boundary layer suction on the aerodynamic performance of a high-turning compressor cascade was numerically simulated and discussed.The aerodynamic performance of a curved and a straight cascade with and ...The impact of boundary layer suction on the aerodynamic performance of a high-turning compressor cascade was numerically simulated and discussed.The aerodynamic performance of a curved and a straight cascade with and without boundary layer suction were comparatively studied at several suction flow rates.The results showed that boundary layer suction dramatically improved the flow behavior within the flow passage.Moreover,higher loading over the whole blade height,lower total pressure loss,and higher passage throughflow were achieved with a relatively small amount of boundary layer removal.The integration of curved blade and boundary layer suction contributed to better aerodynamic performance than the cascades with only curved blade or boundary layer suction used,and the more favorable effect resulted from the weakening of the three dimensional effects of the boundary layer close to the endwalls.展开更多
A new generation conical spray system for conventional diesel engines or premixed combustion diesel engines is introduced. By means of oriented impingement method, flexible spray penetration in design is realized. Hig...A new generation conical spray system for conventional diesel engines or premixed combustion diesel engines is introduced. By means of oriented impingement method, flexible spray penetration in design is realized. High-speed photograph was used to investigate the spatial distribution characteristics of the new spray for cases of different impingement angles and needle valve opening pressures. The results show that, by applying spray impingement orientation, fuel jets spread along the cone surface as shape of sectors, so the dispersion of jets is increased obviously. Changing on impingement angle leads to variation of penetration, which is critical in homogeneous mixture preparation. Due to the flexibility of spray penetration in design, the spray impingement on liner is avoided in a great extent. The results also indicate that higher needle valve opening pressure results in longer penetration and larger spray angle after impingement. Combustion characteristics of the impinged conical spray were studied in the 1135 type diesel engine. The new impinged conical spray system work smoothly in full load range with better fuel economy and lower emissions of NOx and soot than the original test engine.展开更多
The blade row interaction can alter the time-mean flow and therefore be of interest for aerodynamic design analysis. Whereas results within low subsonic turbomachines are quite numerous in the literature, there have b...The blade row interaction can alter the time-mean flow and therefore be of interest for aerodynamic design analysis. Whereas results within low subsonic turbomachines are quite numerous in the literature, there have been far fewer works which give results of blade row interaction within high speed cases. Two cases are related in this paper. First, the effects of an incoming wake on the rotor flow field of a transonic compressor are analyzed. The blade row interaction proved to be positive regarding the total pressure ratio, but negative regarding the losses. The second case concerns a transonic turbine. Particular emphasis is placed on the assessment of the deterministic correlations included in the Averaged Passage Equation System.展开更多
A similitude method to model the tip clearance flow in a high-speed compressor with a low-speed model is presented in this paper.The first step of this method is the derivation of similarity criteria for tip clearance...A similitude method to model the tip clearance flow in a high-speed compressor with a low-speed model is presented in this paper.The first step of this method is the derivation of similarity criteria for tip clearance flow,on the basis of an inviscid model of tip clearance flow.The aerodynamic parameters needed for the model design are then obtained from a numerical simulation of the target high-speed compressor rotor.According to the aerodynamic and geometric parameters of the target compressor rotor,a large-scale low-speed rotor blade is designed with an inverse blade design program.In order to validate the similitude method,the features of tip clearance flow in the low-speed model compressor are compared with the ones in the high-speed compressor at both design and small flow rate points.It is found that not only the trajectory of the tip leakage vortex but also the interface between the tip leakage flow and the incoming main flow in the high-speed compressor match well with that of its low speed model.These results validate the effectiveness of the similitude method for the tip clearance flow proposed in this paper.展开更多
This paper presents the unsteady data acquisition system used to measure the pressure field in high speed compressors.Details and electronic sketches are given for the conditioners developed in-house that have been us...This paper presents the unsteady data acquisition system used to measure the pressure field in high speed compressors.Details and electronic sketches are given for the conditioners developed in-house that have been used to amplify and to filter the pressure signal with the aim of acquiring data up to 150 kHz.A discussion of the experimental results carried out in a centrifugal compressor is proposed.Through different processing of the pressure signals and a comparison with URANS simulations,the excitation of the pressure transducers by the pressure waves generated by shock waves that occur between the impeller and the diffuser is highlighted.The levels of pressure fluctuations measured when entering into surge are also presented and reveal very repetitive behaviour of the flow instabilities.展开更多
The paper describes experimental results obtained using a laser two-focus anemometry technique in a high-speed, high-pressure ratio unshrouded centrifugal compressor. Measurements in such a small impeller are extremel...The paper describes experimental results obtained using a laser two-focus anemometry technique in a high-speed, high-pressure ratio unshrouded centrifugal compressor. Measurements in such a small impeller are extremely difficult as the flow is restricted to narrow passages and as the temperature rise is very high. Even if the working principle of laser anemometry is well documented in literature, some specialities of our LA system are discussed.A description and an analysis of the inlet now field, based on integral methods, are proposed. Some passage velocity contours are presented. Whereas a potential flow structure exists up to the high meridional curvature region, the throughfiow pattern is largely distorted in the radial part of the impeller.Noticeable differences in ftow pattern between both channels are found, particularly through the low momentum fluid zone. A qualitative study of the vortical mechanisms ascribes them to the tip clearance effects.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.50646021).
文摘The impact of boundary layer suction on the aerodynamic performance of a high-turning compressor cascade was numerically simulated and discussed.The aerodynamic performance of a curved and a straight cascade with and without boundary layer suction were comparatively studied at several suction flow rates.The results showed that boundary layer suction dramatically improved the flow behavior within the flow passage.Moreover,higher loading over the whole blade height,lower total pressure loss,and higher passage throughflow were achieved with a relatively small amount of boundary layer removal.The integration of curved blade and boundary layer suction contributed to better aerodynamic performance than the cascades with only curved blade or boundary layer suction used,and the more favorable effect resulted from the weakening of the three dimensional effects of the boundary layer close to the endwalls.
文摘A new generation conical spray system for conventional diesel engines or premixed combustion diesel engines is introduced. By means of oriented impingement method, flexible spray penetration in design is realized. High-speed photograph was used to investigate the spatial distribution characteristics of the new spray for cases of different impingement angles and needle valve opening pressures. The results show that, by applying spray impingement orientation, fuel jets spread along the cone surface as shape of sectors, so the dispersion of jets is increased obviously. Changing on impingement angle leads to variation of penetration, which is critical in homogeneous mixture preparation. Due to the flexibility of spray penetration in design, the spray impingement on liner is avoided in a great extent. The results also indicate that higher needle valve opening pressure results in longer penetration and larger spray angle after impingement. Combustion characteristics of the impinged conical spray were studied in the 1135 type diesel engine. The new impinged conical spray system work smoothly in full load range with better fuel economy and lower emissions of NOx and soot than the original test engine.
文摘The blade row interaction can alter the time-mean flow and therefore be of interest for aerodynamic design analysis. Whereas results within low subsonic turbomachines are quite numerous in the literature, there have been far fewer works which give results of blade row interaction within high speed cases. Two cases are related in this paper. First, the effects of an incoming wake on the rotor flow field of a transonic compressor are analyzed. The blade row interaction proved to be positive regarding the total pressure ratio, but negative regarding the losses. The second case concerns a transonic turbine. Particular emphasis is placed on the assessment of the deterministic correlations included in the Averaged Passage Equation System.
基金supported by National Natural Science Foundation of China(No.51206164,No.51106153,No.51236001)Chinese Academy of Sciences Visiting Professorship for Senior International Scientists Grant No.2001T2G01
文摘A similitude method to model the tip clearance flow in a high-speed compressor with a low-speed model is presented in this paper.The first step of this method is the derivation of similarity criteria for tip clearance flow,on the basis of an inviscid model of tip clearance flow.The aerodynamic parameters needed for the model design are then obtained from a numerical simulation of the target high-speed compressor rotor.According to the aerodynamic and geometric parameters of the target compressor rotor,a large-scale low-speed rotor blade is designed with an inverse blade design program.In order to validate the similitude method,the features of tip clearance flow in the low-speed model compressor are compared with the ones in the high-speed compressor at both design and small flow rate points.It is found that not only the trajectory of the tip leakage vortex but also the interface between the tip leakage flow and the incoming main flow in the high-speed compressor match well with that of its low speed model.These results validate the effectiveness of the similitude method for the tip clearance flow proposed in this paper.
基金the company Turbomeca which supports the centrifugal compressor research program
文摘This paper presents the unsteady data acquisition system used to measure the pressure field in high speed compressors.Details and electronic sketches are given for the conditioners developed in-house that have been used to amplify and to filter the pressure signal with the aim of acquiring data up to 150 kHz.A discussion of the experimental results carried out in a centrifugal compressor is proposed.Through different processing of the pressure signals and a comparison with URANS simulations,the excitation of the pressure transducers by the pressure waves generated by shock waves that occur between the impeller and the diffuser is highlighted.The levels of pressure fluctuations measured when entering into surge are also presented and reveal very repetitive behaviour of the flow instabilities.
文摘The paper describes experimental results obtained using a laser two-focus anemometry technique in a high-speed, high-pressure ratio unshrouded centrifugal compressor. Measurements in such a small impeller are extremely difficult as the flow is restricted to narrow passages and as the temperature rise is very high. Even if the working principle of laser anemometry is well documented in literature, some specialities of our LA system are discussed.A description and an analysis of the inlet now field, based on integral methods, are proposed. Some passage velocity contours are presented. Whereas a potential flow structure exists up to the high meridional curvature region, the throughfiow pattern is largely distorted in the radial part of the impeller.Noticeable differences in ftow pattern between both channels are found, particularly through the low momentum fluid zone. A qualitative study of the vortical mechanisms ascribes them to the tip clearance effects.
