IOSR Journal of Engineering Apr. 2012, Vol. 2(4) pp: 544-554 ISSN: 2250-3021 www.iosrjen.org 544 | P a ge Gas Turbine Engine Anomaly Detection Through Computer Simulation Technique of Statistical Correlation E. A. Ogbonnaya a , H. U. Ugwu a , K. Theophilus-Johnson b . a Department of Mechanical Engineering, Michael Okpara University of Agriculture, Umudike-Umuahia, Nigeria b Department of Marine Engineering, Faculty of Engineering, Rivers State University of Science and Technology, P.M.B. 5080, Port Harcourt, Nigeria Abstract Inefficiencies of compressors and turbines resulting from insufficient pressure ratio at successive blade stages in gas turbines often lead to flow reversals. A step to statistically correlate boost pressure and vibration velocity amplitude to avoid such flow reversals therefore led to the execution of this research. A computer simulation technique was used to actualize this purpose with the operational data obtained from Delta IV unit of Ughelli power station GT 18 using VC++ programming language. Results obtained show that maximum vibration manifests on each of the bearings at a pressure ratio of 9.47 for all cases considered. These results further show a linear relationship between the data using statistical z- test. Keywords: Computer simulation; Statistical correlation; Gas turbine; Anomaly detection; Vibration amplitude; Pressure Ratio. 1. Introduction The marine gas turbine (GT) in many respects is the most significant means of creating mechanical power among the other various means. Although GTs obtain their power by utilizing the energy of burnt gases and air which are at high temperature and pressure while expanding through several rings of fixed and rotating blades [1]. GTs are increasingly being used all over the world for various applications, some of which include power generation, aero-propulsion, propulsion of ships, operation of pumps and compressors [2]. In Nigeria, GTs are used mainly for electricity generation, base-load operations, standby power generating plants including aircraft and ship propulsion. Most oil companies like Agip, Chevron, Elf and Shell also use gas turbines for electricity generation and other purposes [3]. In this paper, an approach is presented for estimating the risk reduction associated with vibration amplitude and boost pressure. VC++ programming language was used to determine the statistical correlation coefficient between boost pressure and vibration amplitude. 1.1. Factors affecting performance GTs operates efficiently if the energy conversion process is operated at the following thermodynamically favorable conditions: 1. High pressure and temperature at the turbine inlet, 2. Minimal losses during compression and expansion. While conversion losses can be minimized through optimal aerodynamic design of the compressor and turbine, the high pressure ratios of 20:1 or greater and turbine inlet temperatures of 1371.11°C and above are desirable for increased efficiency. Effectively, to achieve the thermal efficiencies delivered by modern GTs, they must work at process conditions that push the mechanical and thermal stress of the materials used in the machine’s gas path components to their limits [4]. Ambient conditions affect a GT at both the compressor inlet and the turbine outlet. At the compressor inlet, the higher the temperature and the lower the pressure, the less the mass flow that can be generated through the turbine. Humidity also plays a role. Higher specific humidity increases the specific volume of the inlet airflow, so that the mass flow through the turbine is reduced resulting in less power output and increased heat rate. At the turbine outlet, ambient conditions also play a role. The higher the pressure, the less energy that can be converted to shaft power.