The off-design performance of axial turbines is usually predicted by calculating the incidence losses using empirical correlations. Periodic review and improvement to these prediction methods, to reflect recent turbine designs and test results, are essential for the accurate assessment of losses in turbine airfoils. The purpose of the present work is to evaluate existing turbine incidence loss correlations, and present an improved prediction method for profile and secondary losses at off-design conditions which correlates better with the available experimental results. The incidence losses are shown to be a function of leading edge diameter, pitch, aspect ratio and channel convergence.

A mean line loss system is described, capable of predicting the design point efficiencies of current axial turbines of gas turbine engines. This loss system is a development of the Ainley/Mathieson technique of 1951. The prediction method is tested against the “Smith’s chart” and against the known efficiencies of 33 turbines of recent design. It is shown to be able to predict the efficiencies of a wide range of axial turbines of conventional stage loadings to within ± 1 1/2 percent.

Measurements of mean and fluctuating hydrodynamic properties of two-dimensional, constant property, wall-jet and wall-wake flows are reported. The mean properties include static pressure, velocity and wall shear stress; the fluctuating properties include the three fluctuating components of velocity, the local turbulent shear stress, uv , and u-spectra. The measurements were carried out for four values of the velocity ratio, U C /U G , viz. 0.75, 0.91, 1.33, and 2.3; for values of the ratio of lip thickness to slot height, t/y C , of 0.126 and 1.14; and for values of nondimensional distance, x/y C , between zero and 150. The results demonstrate the difficulties involved in deriving a satisfactory prediction procedure for flows of this type. In the upstream region, normal pressure gradients and separated flow regimes imply the need for elliptic equations. Also in the upstream region, the u-spectra measurements reveal preferred frequencies although the energy contained at the preferred frequency is never more than 25 percent of the total energy. Prandtl mixing length and the Prandtl-Kolmogorov turbulence length scale are deduced from measurements and shown to be very nonsimilar for all values of x/y C . The measurements are reported in sufficient detail to permit the detailed testing of prediction procedures.

Measurements of the mean and fluctuating properties of a two-dimensional, constant property, plane turbulent wall jet in a moving stream are presented and their implications discussed.

This paper presents measurements of the impervious-wall effectiveness of a two-dimensional wall jet obtained using a constant value of lip thickness, 0.032 in. and four slot heights, viz., 0.5, 0.25, 0.132, and 0.074 in. The measurements are in the range of slot-to-free-stream velocity ratio 0.288 ⩽ u ¯ C / u G ⩽ 2.66 and clearly demonstrate that, in the region where the velocity ratio is close to unity, the effectiveness is greatly dependent upon the slot height. The reason for this dependence is investigated and additional measurements are presented to show that the influence of the slot turbulence intensity on the effectiveness is small. It is concluded that the ratio of slot lip thickness to slot height is the most significant parameter and that the effect of an increase in this ratio is to decrease the effectiveness.