Characterization of Failed First-Stage Turbine Blade Cooling Passage of Gas Turbine Engine
- PDF / 2,806,181 Bytes
- 8 Pages / 595.276 x 790.866 pts Page_size
- 46 Downloads / 220 Views
TECHNICAL ARTICLE—PEER-REVIEWED
Characterization of Failed First-Stage Turbine Blade Cooling Passage of Gas Turbine Engine Alaaeldin H. Mustafa
Submitted: 5 August 2013 / in revised form: 27 November 2014 ASM International 2015
Abstract The cooling passages of the first-stage highpressure turbine blades of gas turbine engines are located and drilled at the manufacturing stage. The external wall thickness is a critical blade strength parameter and has to be inspected accurately and regularly when blades are routed through repair work shops. This paper investigates a case of two blades from two different blade sets that experienced cooling passage failure during repair, after serving less than 20,000 operating hours. The investigation covered material microstructure, hardness condition, and material thickness residual assessment, using an ultrasonic nondestructive technique between the first cooling passage and the external blade surface. It was concluded that the first cooling passage was inappropriately drilled during manufacturing. Keywords NDE
Blade cooling passage Drill wander
Introduction A study was conducted to identify the different types of defects in cooling hole produced by shaped-tube electrochemical drilling (STED). The study was set to determine the effects of process parameters on cooling holes quality, diameter and taper, and process parameter values for a given hole quality. The study concluded that for STED, the federate, forward voltage, electrolyte pressure, and metalion concentration are the factors of importance [1]. An A. H. Mustafa (&) Mechanical Services Shops Department, Saudi Aramco, Dhahran, Saudi Arabia e-mail: [email protected]
Eddy current (EC) inspection sensor was designed and implemented for wall thickness evaluation of hollow turbine blade. The work presented showed the advantages of the EC technique in comparison to other none-destructive examination (NDE) techniques. Multiple tests conducted on the quasi-planar areas of different blades indicate good accuracy of wall thickness measurements [2]. Four first-stage high-pressure turbine blade sets of industrial gas turbine engines were sent to the original equipment manufacturer (OEM) facility for repair due to outer surfaces coating damage. The repair work scope included external and internal coating stripping, welding of the buckets tips after pre-weld heat treatment, post-weld heat treatment, and external and internal re-coating. Nondestructive test (NDT) has been performed several times after the various repair stages. After the re-application of the internal aluminized coating, NDT revealed two different blades from two different blade sets with two pin-like holes. The observed pin-like holes were not present prior to the internal coating re-application. Based on that observation, it was assumed that the pin-like holes were developed during the re-application of the internal aluminized coating process. The engines, from which the blade sets were removed, were of the same model, with the blades having the s
Data Loading...
