A Review and Analysis of Boundary Layer Transition Data for Turbine Application

Abstract

A Symposium on Transition in Turbines was held recently at the NASA Lewis Research Center. One recommendation of the working groups was the collection of existing transition data to provide standard cases against which models could be tested. This paper represents a preliminary response to that recommendation. A number of data sets from the open literature that include heat transfer data in apparently transitional boundary layers, with particular application to the turbine environment, were reviewed and analyzed to extract transition information from the heat transfer data. The data were analyzed using a version of the STAN5 two-dimensional boundary layer code. The transition starting and ending points were determined by adjusting parameters in STAN5 until the calculations matched the data. The results are presented as tables of the deduced transition location and length as functions of the test parameters. The data sets reviewed cover a wide range of flow conditions, from low speed, flat plate tests to full scale turbine airfoils operating at simulated turbine engine conditions. The results indicate that free stream turbulence and pressure gradient have strong, and opposite, effects on the location of the start of transition and on the length of the transition zone.

Aerodynamics and Heat Transfer Investigations on a High Reynolds Number Turbine Cascade

“…Since the existing transition models incorporated in the code do not adequately describe the transition phenomenon under turbomachinery condition, a quantitative prediction remains questionable. Test studies reported by Gaugler (1985) show that, without the exact knowledge of the transition start point and length, with STAN5, a number of iterations must be performed until a reasonable agreement between computed and measured results is obtained. The results presented in this report indicate that the existing boundary layer calculation methods in integral or differential form cannot be considered as a reliable a priori predictive design tool unless the basic mechanisms mentioned above are completely described and implemented into the calculation procedure.…”

Effect of Free-Stream Turbulence, Reynolds Number, and Incidence on Axial Turbine Cascade Performance

“…For the Reynolds number range encountered in gas turbines, the profile boundary layers are highly transitional, and the usual simplifying assumption that the profile layers are turbulent from the leading edge onward is generally wrong and not necessarily conservative (Gostelow, 1983). Besides being a requirement in predicting profile losses, knowledge on the state of the profile boundary layer is also necessary for the design of efficient blade cooling systems (Gaugler, 1985).…”

Effect of Unsteady Wake Passing Frequency on Boundary Layer Transition, Experimental Investigation and Wavelet Analysis

“…Wittig and his coresearchers (Wittig et al 1988, Dulenkopf 1992) conducted a series of extensive studies investigating the wake effect on the gas turbine heat transfer. Investigations by Gaugler (1985) and Schobeiri, et al (1991) show that the existing correlations primarily developed for external aerodynamics applications are not capable of correctly predicting the unsteady transition behavior of gas turbine blades. The detailed study by Mayle (1991) and the follow up discussion by Walker (1993) underscore the role and the significance of transition in turbomachinery.…”