Title page for ETD etd-10122005-134445


Type of Document Dissertation
Author Feng, Ming-Fa
URN etd-10122005-134445
Title Fault diagnosis and prediction in reciprocating air compressors by quantifying operating parameters
Degree PhD
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Mitchiner, Reginald G. Committee Chair
Knight, Charles Eugene Committee Member
Leonard, Robert G. Committee Member
Singh, Mahendra P. Committee Member
Wicks, Alfred L. Committee Member
Keywords
  • Machine parts Failures Mathematical models.
  • Air-compressors Mathematical models.
Date of Defense 1992-03-05
Availability restricted
Abstract

This research introduces a new method of diagnosing the internal condition of a reciprocating air compressor. Using only measured load torques and shaft dynamics, pressures, temperatures, flow rates, leakages, and heat transfer conditions are quantified to within 5%.

The load torque acting on the rotor of the machine is shown to be a function of the dynamics (instantaneous position, velocity, and acceleration) of the driving shaft, the kinematic construction, and the internal condition of the machine. If the load torque, the kinematic construction of the machine, and the dynamics of the rotor are known, then the condition of the machine can be assessed.

A theoretical model is developed to describe the physical behavior of the slider-crank mechanism and the shaft system. Solution techniques, which are based on the machine construction, crankshaft dynamics, and load torque measurements, are presented to determine the machine parameters. A personal computer based system used to measure the quantities necessary to solve for the machine parameters and the quantities used to compare with calculations is also documented.

The solution algorithm for multi-stage compressors is verified by decoupling the load torque contributed by each cylinder. Pressure data for a four-stage two-cylinder high pressure air compressor (HPAC) is used. Also, the mathematical model is proven feasible by using measured angular velocity of the crankshaft and direct measurements of the load torque of a single stage, single cylinder air compressor to solve for the machine parameters.

With this unintrusive and nondestructive method of quantifying the operating parameters, the cylinder pressures, operating temperatures, heat transfer conditions, leakage, and power consumption of a reciprocating air compressor can be evaluated.

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