A control system for a compression-ignition engine is provided, which includes an engine having a combustion chamber, an injector configured to supply fuel into the combustion chamber, a spark plug, a swirl valve provided to an intake passage of the engine, and a controller. The controller includes a processor configured to execute a swirl adjusting module to adjust a swirl valve opening to generate a swirl flow inside the combustion chamber, a fuel injection amount controlling module to control fuel injection amounts of pre-injection and post-injection so as to increase a ratio of an injection amount of the post-injection to a total fuel injection amount into the combustion chamber in one cycle as an engine speed increases, and a combustion controlling module to control the spark plug to ignite at a given ignition timing after the swirl generation and fuel injection, so that partial compression-ignition combustion is performed.

A method of thrust control for an airbreathing jet engine includes obtaining a demanded thrust setting, a value of static pressure at a first axial location of a combustion chamber of the airbreathing jet engine and a value of static pressure at a second axial location of the combustion chamber of the airbreathing jet engine. The second axial location is downstream of the first axial location. The method also includes obtaining a ratio of the value of static pressure at the first axial location of the combustion chamber to the value of static pressure at the second axial location of the combustion chamber; and controlling a fuel flow rate of the airbreathing engine based at least in part on the demanded thrust setting and the ratio of the value of the static pressure at the first axial location to the value of the static pressure at the second axial location.

A control system of an engine is provided, which includes a piston formed with a cavity and configured to reciprocate in a cylinder along a center axis of the cylinder, and a fuel injector disposed facing a top surface of the piston and configured to inject fuel along an injection axis. When the piston is located near a top dead center of compression stroke, the fuel injector performs a first injection so that the fuel flows from the fuel injector toward the cavity along the injection axis, collides with an inner surface of the cavity, then flows back toward the fuel injector along the inner surface of the cavity from a position offset from the injection axis. The fuel injector performs a second injection toward the cavity at a timing after the first injection and at which the fuel of the first injection flows back.

A diesel engine includes a piston, a cylinder head, and a fuel injector. The fuel injector has a valve body with bored nozzle holes in its tip part. A cavity having a circular shape in plan view is formed in a crown surface of the piston to concave to the counter cylinder head side. A wall surface constituting the cavity has a central ridge portion bulging toward the fuel injector while bulging larger toward the center of the cavity, a periphery concave portion formed radially outward of the central ridge portion to concave radially outward, and a lip portion formed between the periphery concave portion and the crown surface to convex radially inward. A lip radius R, a nozzle hole length L, a nozzle hole diameter D, and a bore radius B are designed to satisfy the following equation:
99.4D(13D)(L+2.7)Rmin{237.1D(13D)(0.8L+1),2B/3}.

Various methods and systems are provided for a combustion system of an engine. In one example, a combustion system comprises a piston crown bowl with a central apex, a combustion chamber operable at a compression ratio in a range of from about 13:1 to about 17:1, the combustion chamber formed at least partially by the piston crown bowl, and a fuel injector with a nozzle extending into a central portion of the combustion chamber that is operable to inject fuel directly into the combustion chamber, the nozzle defining a number of apertures that is in a range of from six to ten.

A method of thrust control for an airbreathing jet engine includes obtaining a demanded thrust setting, a value of static pressure at a first axial location of a combustion chamber of the airbreathing jet engine and a value of static pressure at a second axial location of the combustion chamber of the airbreathing jet engine. The second axial location is downstream of the first axial location. The method also includes obtaining a ratio of the value of static pressure at the first axial location of the combustion chamber to the value of static pressure at the second axial location of the combustion chamber; and controlling a fuel flow rate of the airbreathing engine based at least in part on the demanded thrust setting and the ratio of the value of the static pressure at the first axial location to the value of the static pressure at the second axial location.