Engine Performance Data Research Articles

A Method of Estimating the Off-Design Performance of Simple Axial Turbo-Jet Engines

The method described in this paper can be used to calculate the performance of the simple axial turbo-jet engine (one stage turbine, fixed area jet nozzle) within almost all practical revolution range including the maximum, and simpler in its procedure than any other methods already published. This can be applied, however, only for the engines in which (1) An axial compressor, of which characteristics can be represented by the two curves according to Howell's method, is used. (2) Expansion ratio of both turbine and jet nozzle are equal to or more than crytical. (3)Turbine adiabatic efficinency can be assumed constant within the range considered. These conditions simplify the power balance and mass flow balance equations, and operational matching point of every element is to be easily found by the help of graphical method. The comparisons between the published performance data of an actual engine and results of the calculation according to this paper are also presented here.

An Application of Carpet and Lattice Plotting

The carpet and lattice methods of plotting the relationship between three and four variables respectively, developed by R. F. Sargent, of the National Physical Laboratory, have been described previously by A. H. Yates, who gave examples related to the presentation of aerodynamic and engine performance data. Outside these fields there appears to be still some lack of appreciation of the usefulness of this form of graphical representation, although it is capable of wide application. The writer has found both carpet and lattice plotting of great value in connection with the preparation of structures data sheets, and is convinced that interpolation is generally rendered easier and more accurate if graphical data are presented in this way. In one particular instance it was found possible to develop a nomogram in the form of an “ extended lattice ” plot, which gave in graphical form a direct solution to a set of equations which could be solved otherwise only by continuous approximation.

Performance of 161-Kv and 115-Kv Transmission Lines

This paper presents engineering and lightning performance data on the Tennessee Valley Authority's 161-kv and 115-kv transmission lines. Normal maximum line loadings are tabulated, and certain transmission line operating practices are described.