F. A. E. Breugelmans

Rotor blade-to-blade measurements using Particle Image Velocimetry

The study of turbomachinery flow fields requires detailed experimental data. The rotating parts of turbomachines greatly limit the measurement techniques that can be used. Particle Image Velocimetry (PIV) appears to be a suitable tool to investigate the blade-to-blade flow in a rotor. The facility is a subsonic axial-flow compressor. The experimental apparatus enables the recording of a double-exposed photograph in a circumferential plane located at 85 percent of the blade height. The illumination plane has an axial direction and is provided by a pulsed ruby laser. The tracers used are submicron glycerine oil droplets. Data are processed by Youngs fringes method. Measurements were performed at 3000, 4500, and 6000 rpm with velocities in the range of 30 to 70 m/s. Steady operating conditions are chosen in such a way that the effect of radial velocity on PIV measurements can be neglected. Experimental problems encountered included homogeneous seeding of the flow field and laser light scattering from blade surfaces. The uncertainty affecting the velocity determination corresponds to 2 percent of the measured value. For a given set of operating conditions, 10 PIV pictures are recorded. The periodic flow field is approximated by averaging the experimental data point by point. Upstream and downstream velocity triangles are confirmed by measurements obtained from pressure probes. PIV measurement results were found to be similar to those of a blade-to-blade potential-flow calculation.

Experimental Investigation of the Blade-to-Blade Flow in a Compressor Rotor by Digital Particle Image Velocimetry

The purpose of this study is to investigate the blade-to-blade flow in an axial compressor, providing a detailed description of the entire flow-field on multiple layers through the use of Particle Image Velocimetry (PIV). Typical problems that relate to flow seeding, light-sheet generation, and camera-laser timing control are successfully dealt with, bringing additional knowledge in the domain. An extensive data set is analyzed to obtain statistical flow information (mean and fluctuating quantities). Spatial data reconstruction procedures allow the complete planar flow distributions to be determined. The multiplanar mean velocity field constitutes the final result of a three-dimensional reconstruction of the domain geometry and the proper introduction of the available planar measurements.

Rotor Blade-to-Blade Measurements Using Particle Image Velocimetry

The study of turbomachinery flow fields requires detailed experimental data. The rotating parts of turbomachines greatly limit the measurement techniques which can be used. Particle Image Velocimetry (PIV) appears to be a suitable tool to investigate the blade-to-blade flow in a rotor.The facility is a subsonic axial-flow compressor. The experimental apparatus enables the recording of a double exposed photograph in a circumferential plane located at 85 % of the blade height. The illumination plane has an axial direction and is provided by a pulsed Ruby laser. The tracers used are sub-micron glycerine oil droplets. Data are processed by the Young’s fringes method.Measurements were performed at 3000, 4500 and 6000 RPM with velocities in the range of 30 to 70 m/s. Steady operating conditions are chosen in such a way that the effect of radial velocity on PIV measurements can be neglected.Experimental problems which are encountered included homogeneous seeding of the flowfield and laser light scattering from blade surfaces. The uncertainty affecting the velocity determination corresponds to 2 % of the measured value.For a given set of operating conditions, 10 PIV pictures are recorded. The periodic flow field is approximated by averaging point by point the experimental data. Upstream and downstream velocity triangles are confirmed by measurements obtained from pressure probes. PIV measurement results were found to be similar to those of a blade-to-blade potential-flow calculation.Copyright

Design and Experimental Verification of an Optimised Compressor Blade

This paper deals with the design of an optimised compressor blade and the experimental verification of its performance at design and off-design operation.Starting from an existing controlled-diffusion blade, a new two-dimensional blade section has been designed by means of an inverse method, maintaining the same flow turning. Optimisation is made to achieve lower losses over an incidence range of 10 degrees while care has been taken to keep the blade thickness within prescribed tolerances.The blade has been manufactured and tested in the C1 low speed cascade tunnel of the von Karman Institute. Experiments confirm substantial performance improvements at the blade mid section over the whole range of incidences. Measurements near the side walls show that the secondary flow losses are unchanged.Verifications with a Navier-Stokes solver show a remarkable agreement with measurements and flow visualisations and explain the reasons for the important performance improvement at high incidence.Copyright

Unsteady Flow in Axial Flow Compressors

A review is made of the experimental rotating stall work on a low-speed compressor stage. The instantaneous flow field inside the cell is explored using multiple hot wires in the absolute frame of reference. Rotor blade stall and radial drift of the boundary layer is investigated by on-rotor blade instrumentation. The large flow variations suggest a strong unsteady behavior of the blades, which is demonstrated by the unsteady loss-incidence curve as measured with fast response instrumentation in the relative motion.