TRANSIENT TESTING TO DETERMINE HEAT TRANSFER COEFFICIENT AND WALL THICKNESS OF TURBINE BLADES

摘要

The integrity of interior passages of cast components, such as turbine blades, is critical to the functionality of these components. Testing methods, which provide a timely judgment of the passages, is essential to the cost effective production of these parts. The goals of this project is to estimate the local internal heat transfer coefficients and wall thickness using inverse heat transfer techniques from the transient response exhibited by the exterior wall temperature to a sudden change in the air flow temperature within the passages. The desired result is a computationally efficient test that can both shorten and improve the inspection of cast turbine blades. The work described here is an initial effort examining feasibility. A first order, one dimensional heat transfer model is assumed through a thin wall. Simulated experimental data is generated from the forward heat transfer problem for a wall with initial temperatures equal to ambient room temperature with one side of the wall suddenly exposed to high temperature forced convection while the other is left exposed to ambient natural convection. Random Gaussian noise is superimposed on the simulated data. The Levenberg-Marquardt technique is examined to determine heat transfer coefficients, wall thickness, and its accuracy.