Centrifugal compressors, which serve the purpose of internal combustion engines (ICE) supercharging, have a region of unstable operation. The compressor instabilities can be distinguished as rotating stall, mild, or deep surge, depending on the compression system parameters. All these types of compressor operation should be avoided for engine durability and long service life. Therefore, it is important to provide fast, stable, and correct prediction of compressor instabilities at ICE operating cycle simulation. The experimental research was conducted for an aircraft engine compressor to measure compressor performance map in the region of unstable operation, which is usually never provided by the manufacturer, and to study the compression system operation in the mild and deep surge modes. A mathematical model was developed, based on the Moore-Greitzer approach together with the modified equation of the compressor outlet pipe airflow acceleration, and integrated into the Blitz-PRO service for ICE steady and transient operation simulation. It is shown that the suggested mathematical model correlates well with the experimental data for the compressor testbench case. The application of the developed mathematical model provides fast and stable calculations and prediction of the type of compression system instability.

The scheme of the cooling system is considered, which can be the basis for creating the most efficient cooling systems for IC engines of any purpose. It is assumed that the use of any other scheme is devoid of a rational basis. The scheme consists of two connected circulation circuits, in one of...

EFFECT OF THERMAL INERTIA ON DIESEL ENGINES TRANSIENT PERFORMANCE

Modern cooling systems for large ships are quite complex. As a rule, such systems are common (combined) for the main and auxiliaries engines. With the auxiliary engines running constantly, even when parked, this system design allows to keep it warm and ready for a quick start of the main engines...

Rational designs for cooling systems (CS) of internal combustion engines are formulated in the form of a series of circulation circuits. The engine is integrated into a circuit with the highest and unregulated flow of internal circuit coolant (ICC). All heat exchangers are placed in circulation circuits with relatively reduced and adjustable ICC flow rates. While the circuits are usually interconnected, they can also be designed to operate independently. This CS scheme enables the achievement of the minimum possible value of the sum of masses of exchanger cores, denoted as M_Σ. The reduction in M_Σ is achieved through the regulation of ICC flow in a closed circulation loop involving two heat exchangers. The variations in M_Σ based on the circuit parameters have been thoroughly investigated. The reduction in M_Σ can also be applicable to more intricate systems. A decrease in M_Σ, under identical initial CS parameters, may occur in different magnitudes, depending on the specific features of the CS scheme and the operating conditions of the heat exchangers within it. Cooling systems, constructed with the same initial parameters and comprising multiple circulation circuits that meet all criteria for rational design, may exhibit diverse configurations. Examples of such systems are explored, and the minimum values of M_Σ are calculated for each. It has been determined that the disparity in the minimum values of M_Σ for such systems, while maintaining equal efficiency, can exceed 30%. The selection of the optimal CS scheme is contingent not only on achieving the minimum possible value of M_Σ but also on various other factors.