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Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 99-102). Also available via the Internet.

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The correlation of cascade experimental data is one method for obtaining compressor stage characteristics. These correlations specify pressure loss and flow turning caused by the blades. Current open literature correlations used in streamline curvature codes are inadequate for general application to high-speed transonic axial-flow compressors. The objective of this research was to investigate and evaluate the available correlations and ultimately discover sets of correlations which best fit the empirical data to be used in streamline curvature codes. Correlations were evaluated against experimental data from NASA Rotor 1-B and NASA Stage 35. It was found that no universal set of correlations was valid for minimum-loss point predictions. The Bloch shock loss model showed promising results in the stall regime for supersonic relative inlet Mach numbers. The Hearsey and Creveling off-minimum-loss deviation angle prediction performed consistently better than all other correlations tested. / Master of Science

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A multichannel FM telemetry system was employed to measure the dynamic response of compressor rotor blade surface pressure profiles to changes in upstream conditions. Data taken while the experimental compressor was operating with a distortion screen upstream of the rotor was utilized to develop a transfer function to describe the dynamic response of the rotor blade row. The transfer function was developed by considering the dynamic total pressure loss distribution around the rotor to be a response function driven by a quasi-steady total pressure loss distribution as a forcing function. Fourier transforms of both the dynamic and the quasi-steady distributions were calculated. The quotient obtained by dividing the Fourier transform of the response function by the Fourier transform of the forcing function was the desired transfer function. This experimentally-determined transfer function was then used in a new semi-actuator disc model to predict the dynamic response of the experimental compressor. The basis of the model is a mathematical representation of the flow fields upstream and downstream of a compressor rotor. The compressor rotor is represented in the model by a semi-actuator disc. The results of the investigation show that the physical mechanisms which control the onset and propagation velocity of a rotating stall in a single-stage compressor can be modeled with the use of a transfer function in a semi-actuator disc model of the compressor. The transfer function represents the dynamic characteristics of the compressor rotor row as an amplitude ratio and a phase shift of the Fourier frequency components of the total pressure loss distribution. This transfer function representation of the dynamic characteristics of the blade row provides important advantages over previous techniques. / Ph. D.

The main objective of this research effort was the construction of a finger valve dynamics model using simplified theory based on steady flow conditions. The analytical valve positions were then compared to experimental measurements from an Ingersoll Rand model 242 two-stage air compressor. Proximity probes were used to measure the valve position at two points on the exhaust valve at two different exhaust valve stop heights and at two points on the intake valve at one intake valve stop height in the lower exhaust valve stop height configuration only. A data acquisition system was configured to signal average and digitize the analog data from the sensors using a digital oscilloscope. The data was then sent to and stored in data acquisition computer for future comparisons to analytical results. The comparisons of the analytical and experimental exhaust valve positions at both points and both valve stop heights were of good quality when the effects of oil stiction were taken into account. Also, the comparisons of the intake valve positions were of good quality after adjustments were made in the theoretical force on the valve calculation. The adjustments entailed accounting for flow-induced forces on the intake valve after piston reversal. Overall the simplified model predicted the valve positions with sufficient quality to warrant the model's use as a design tool. / Master of Science

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Approved for public release, distribution unlimited / This thesis presents a Computation Fluid Dynamics (CFD) analysis of the aerodynamic performance of circular and elliptical leading edges of compressor blades, with a range of leading-edge droop angles. Specifically, simulations were conducted, with a free stream Mach number of 0.65 to quantify the change in pressure distributions and boundary layer momentum thickness in the leading edge region for a range of incidences on a flat plate with various leading-edge ellipticity ratios, ranging from unity (circular) to 5.5. In addition, the impact of drooping the leading edge was analyzed over a range of incidence angles from zero to 13 degrees. Pressure distributions indicate that elliptical leading edges can eliminate separation bubbles at zero incidence. The results indicated that the minimum loss occurred at an ellipticity ratio of about 3 and elliptical leading edges with a droop slightly greater than the average incidence can significantly decreased aerodynamic losses over a wider range of incidences.