Irregularity of static working states of ship combustion piston engine

Abstract

Variability of static working conditions of combustion engine in the range of higher frequencies has character of noise resulting from phenomena not taken directly into account in test program as well as from features of measuring systems. Knowledge of features of the noise contained in observed static signals is important for determining the representative values taken as static and slow-changeable in conditions of unavoidable disturbances. The tests in question were carried out in the static working conditions of a 6AL 20/24 Sulzer diesel engine, determined by the torque Me = 4.33 kNm and the rotational speed n = 660 min^–1. The following quantities characterizing emission of pollutants contained in exhaust gas in the conditions described by the engine working point : torque, rotational speed and concentrations of carbon oxide, hydrocarbons and nitrogen oxides, were selected for analyses. The tests were performed in the domains of time, process values and frequency. It was stated that the observed runs of the noise generated by phenomena not directly accounted for in combustion engine static test program and by measuring systems, had mainly the character of uncorrelated broad-band normal noise. The results justify a.o. correctness of averaging the measurement results obtained in static conditions as well as synchronous averaging in steady conditions.