ASSESSMENT OF CALCULATING ERRORS OF A NON-STATIONARY OPERATING MODE OF THE GAS PIPELINE

Abstract

The author of this work offers the way of definition of the internal calculating error of methods of the gas pipeline hydraulic calculation. The offered way is applicable both to stationary model, and to the most general case - to the model describing non-stationary process. This way is shown on the calculation of the known system of the equations which describes non-stationary process by "the way with variable coefficients". But this way of calculation was considerably modified by the author for the accounting of heat exchange, and for gravity influences. But this way of calculation was considerably modified by the author for the accounting of heat exchange, and for gravity influences. The initial "way with variable coefficients" didn't consider these factors that attracted considerable errors. The mentioned adjustment is described in detail by the author in the other publication. The offered way of definition of the internal calculating error of methods of the gas pipeline hydraulic calculation includes the analysis on each component of the initial equation of movement of compressed liquid. The author gives formulas for definition of influence of all factors entering this equation. The main thing of definition of an internal calculating error is the comparison of the sum of influence from all factors which sizes are received as a result of calculation for the chosen method with basic data for the same calculation. These data are provided to a uniform scale for possibility of carrying out procedure of comparison. As such scale the size of change of gas pressure in the course of its movement on the gas pipeline is accepted. The author defines changes of pressure according to the following factors: change of gas energy in volume because of not stationarity of process, change of kinetic energy of gas, influence of friction forces and weight. The sum of changes of all these factors pressure is compared with the general pressure difference on the gas pipeline that is set in basic data of calculation. Their distinction defines an internal calculating error of the estimated method. The offered way is shown on calculation of the concrete example. The author shows settlement ratios for all counted parameters, and results of calculation, are presented by numbers or graphically for the offered example.