Mean Velocity and Decay Characteristics of the Near and Far-Wake of a Compressor Rotor Blade of Moderate Loading

Abstract

This paper reports the experimental study of the three-dimensional characteristics of the mean velocity in the wake of a moderately loaded compressor rotor blade. The measurements were taken with a three-sensor hot-wire probe rotating with the rotor. The wake was surveyed at several radial and axial stations. The loading was found to have substantial effect and this was reflected not only in the axial and tangential components, but also in the radial component. The radial velocities were found to be high very near the trailing-edge and this exhibits the characteristics prevalent in a trailing vortex system. The static pressures across the wake were measured using a direction insensitive spherical head static-stagnation pressure probe. The static pressure was found to be higher inside the wake. These and other measurements are reported and correlated in this paper.

Design of a Kaplan turbine for a wide range of operating head -Curved draft tube design and model test verification-

“…As for turbomachines, if the instability of the wake shedded from the rotating blade gets transported, the hydraulic problems are induced to confine the operating range. As for common compressors and pumped machines, the wake flow induced secondary flow often occurs among blades, and even between the rotating and stationary blades to compromise the turbine performance in off-design operations [1,2]. As for hydro turbine, the secondary flow involved blade wake often sheds and curls up to the downstream to induce turbulence eddy and swirl to the draft tube.…”

Measurement and Analysis of the Periodic Variation of Total Pressure in an Axial-Flow Compressor Stage.

“…In making this comparison, it is important to realize that the static pressure is not necessarily constant at any radial position. Ravindranath and Lakshminarayana (1979) This reasoning was used earlier (Wagner and Okiishi (1977)) to explain observed periodic variations in local velocities. The velocity polygons shown in Figure 4.8 in combination with the periodically varying cascade plots of Wagner and Okiishi (1977) shown in Figure 4.7 and the observed location of the rotor wakes relative to the IGV wake avenues suggest, as might be expected, that interacted wakes generally involve lower total-head values than noninteracted wakes.…”

“…In this case, the relative flow angle was larger in the wake region than in the freestream, while the absolute velocity was smaller in the wake region. Ravindranath and Lakshminarayana (1979) have taken data behind a rotor row with an IGV row farther (several Kerrebrock and Mikolajczak (1970).…”

Axial Flow Fan Tip Leakage Flow Control Using Tip Platform Extensions

“…It is a significant source of aerodynamic loss and affects the efficiency and vibration characteristics. References [9][10][11] deal with extensive investigations of the wake flow features such as mean velocities, turbulence and decay characteristics on turbomachinery performance.…”