AEROTHERMODYNAMICS OF AXIAL-FLOW COMPRESSORS WITH WATER INGESTION
Abstract
In order to establish the extent and nature of overall performance changes in an axial-flow air compressor with water-ingestion, an experimental investigation was conducted on a six-stage machine with (i) air-water droplet mixture flow and (ii) air-methane mixture flow (methane substituted for water vapor). The results showed the manner in which various overall performance parameters became affected and deteriorated due to the presence of water and water vapor in the working fluid. The effect of water ingestion into a compressor was examined in terms of five processes related to the two-phase nature of the flow: (i) changes in the thermo-physical properties, (ii) droplet-fluid-blade interaction, (iii) aerodynamic performance change, (iv) centrifugal action, (v) heat and mass transfer between the two phases and (vi) droplet size adjustment. A numerical-computational program, the PURDU-WICSTK Code, was developed by incorporating the aforementioned six processes into a "meanline" scheme for the calculation of performance of compressors. Predictions were obtained for the test compressor utilizing the code. Comparisons with experimental data confirmed the applicability of the model for determining the nature of changes in overall performance under various operating and mixture entry conditions. An analysis of the predictions was carried out in order to determine the relative importance of the processes incorporated into the prediction model directly and on the basis of (i) the characteristic residence times and (ii) the radial distortion in fluid properties. It was found that the change in the aerodynamic performance of blading and the effect of centrifugal action play the most dominant roles in all cases, while the transfer processes are especially significant in certain cases; the magnitude of the absolute contents of water and water vapor affect the relative importance of different processes. The effect of water ingestion into axial-flow air compressors may be summarized in terms of two factors: (i) distortion in the state of fluid and (ii) change in the overall performance, including the occurrence of surge and choking conditions.
Degree
Ph.D.
Subject Area
Aerospace materials
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