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

摘要

A fast-response, total-pressure probe was used with a periodically sampling and averaging data acquisition system to study the unsteady total-pressure field in an axial-flow turbomachine. Periodically unsteady total-pressure data were used to demonstrate some of the ways in which turbomachine blade wake transport and interaction influences the energy transfer involved. Observed trends of periodic variations in local total pressures could be explained in terms of the details of energy transfer associated with the different kinds of fluid particles (freestream, wake segment, blade surface boundary layer, mixed) moving through a blade row. Some frequency response requirements of measurement systems used for turbomachine unsteady total pressure research are proposed. Examples of how the system and its components (probes, filters and amplifiers) respond to idealized wakes illustrate the necessity of a system that will faithfully respond to anticipated wake forms. The importance of the harmonic content of the unsteady data being measured is demonstrated. (Author)