An experimental investigation of reversed flow performance characteristics in a compressor cascade was conducted. The purpose was to gain a fundamental understanding of reversed flow in a compressor blade cascade, and to determine the effects of stagger angle and angle of attack on the reversed flow behavior in the cascade. Tests were conducted at two blade configurations, one to simulate reversed flow in a compressor rotor and one to simulate reversed flow in a compressor inlet guide vane. Three stagger angles were tested for each configuration with an absolute angle of attack range from 70 to 130 degrees. The investigation included total and static pressure measurements upstream and downstream of the cascade as well as blade surface measurements. Aerodynamic performance parameters were presented for a reversed flow cascade. Comparison of corrected total pressure loss curves suggested that blade rows of a compressor subjected to reversed flow may be treated as nearly equal loss producers. A comparison was made between total pressure loss coefficients from this investigation and experimental compressor performance. The total pressure loss coefficients compared favorably in magnitude and curve shape. / Master of Science

Oil ring seals are one major source of instability in high pressure centrifugal compressors. This thesis presents a method for analysis of an improved seal concept that has been used in very high pressure designs (900 PSI). The improved design uses a combination of ring seals and tilting pad bearing elements. The stable tilting pad is used to center the heavily grooved seal element. The eight stiffness and damping coefficients which represent the hydrodynamic forces between the journal and the seal assembly are computed by an automated computer code for evaluation of both the standard ring seal and the tilting pad elements. Both synchronous and nonsynchronous steady state characteristics have been included in the analysis. The nonsynchronous whirl of the rotor and its effects on the stiffness and damping coefficients of a 5 tilting pad seal have been given in the form of design curves. The effect of pad inertia which has been neglected in many bearing analysis codes has been incorporated in this seal analysis, and allowed the determination of the exact cross coupling stiffness and damping coefficients. / Master of Science

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