Abstract: A particle image velocimetry system is provided which supplies tracer particles to a flow field around an object (12) from tracer particle supply means, takes an image of reflected light by imaging means (32A, 32B) by irradiating the tracer particles twice with laser light at different times, and determines a velocity vector of the flow field based on the two images obtained of the tracer particles. The two images are each divided into a plurality of test regions, and when first peak value (fp)/second peak value (sp)?1.2 is satisfied by comparison between a first peak value fp and a second peak value sp of a cross-correlation value of a luminance pattern of tracer particles in each test region of the two images, it is determined that the reliability of the velocity vector is high. Thus, it is possible to enhance the precision of measurement of the state of flow by reliably determining erroneous vectors.

Abstract: A particle image velocimetry system is provided which supplies tracer particles to a flow field around an object (12) from tracer particle supply means, takes an image of reflected light by imaging means (32A, 32B) by irradiating the tracer particles twice with laser light at different times, and determines a velocity vector of the flow field based on the two images obtained of the tracer particles. The two images are each divided into a plurality of test regions, and when first peak value (fp)/second peak value (sp)?1.2 is satisfied by comparison between a first peak value fp and a second peak value sp of a cross-correlation value of a luminance pattern of tracer particles in each test region of the two images, it is determined that the reliability of the velocity vector is high. Thus, it is possible to enhance the precision of measurement of the state of flow by reliably determining erroneous vectors.

Abstract: At least part of the inner circumferential wall of the outer casing is provided with a concave surface opposing the rotor blade tips as seen in a longitudinal section. Typically, each of the rotor blades is provided with aerofoil section, and the compressor is designed as a transonic axial flow compressor. Thereby, a compressive wave is produced upstream of the shockwave so that the Mach number of the flow entering the shockwave can be reduced. As a result, the shockwave is made less severe, and the shockwave loss can be reduced. In particular, because the concave surface is provided in the casing wall as opposed to the case where the concave surface is provided in the negative pressure side of the rotor blade, the reduction in the performance owing to the change in the angle of the airflow entering the passage defined by the concave surface under a partial load condition can be avoided.

Abstract: In an axial flow compressor, an apical angle at a leading edge of a stator blade progressively increases from a root end to a tip of the stator blade whereby the stator blade loss and noises caused by unsteady inter-blade airflow can be minimized. Preferably, the apical angle at the tip of the stator blade is 1.5 to 2.5 times of the apical angle at the root of the stator blade.

Abstract: In an axial flow compressor, an apical angle at a leading edge of a stator blade progressively increases from a root end to a tip of the stator blade whereby the stator blade loss and noises caused by unsteady inter-blade airflow can be minimized. Preferably, the apical angle at the tip of the stator blade is 1.5 to 2.5 times of the apical angle at the root of the stator blade.

Abstract: In a stator vane arrangement including a plurality of stator vanes axially opposing a plurality of rotor vanes in rotating machinery, each stator vane is tilted with respect to a radial line so that the load acting on the hub end of each stator vane is reduced and a secondary flow is minimized. This allows the aspect ratio of each stator vane to be reduced, and the number of stator vanes to be reduced without impairing the efficiency of the rotating machinery. This in turn allows the frequency of the oscillator force produced by the stator vane in relation with the motion of the rotor vanes to be lowered so that a resonant condition of the stator vanes can be avoided relatively easily.

Abstract: At least part of the inner circumferential wall of the outer casing is provided with a concave surface opposing the rotor blade tips as seen in a longitudinal section. Typically, each of the rotor blades is provided with aerofoil section, and the compressor is designed as a transonic axial flow compressor. Thereby, a compressive wave is produced upstream of the shockwave so that the Mach number of the flow entering the shockwave can be reduced. As a result, the shockwave is made less severe, and the shockwave loss can be reduced. In particular, because the concave surface is provided in the casing wall as opposed to the case where the concave surface is provided in the negative pressure side of the rotor blade, the reduction in the performance owing to the change in the angle of the airflow entering the passage defined by the concave surface under a partial load condition can be avoided.

Abstract: In a stator vane arrangement including a plurality of stator vanes axially opposing a plurality of rotor vanes in rotating machinery, each stator vane is tilted with respect to a radial line so that the load acting on the hub end of each stator vane is reduced and a secondary flow is minimized. This allows the aspect ratio of each stator vane to be reduced, and the number of stator vanes to be reduced without impairing the efficiency of the rotating machinery. This in turn allows the frequency of the oscillator force produced by the stator vane in relation with the motion of the rotor vanes to be lowered so that a resonant condition of the stator vanes can be avoided relatively easily.