Combustion system including a piston crown and fuel injector
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.
1. A combustion system, comprising:
a cylinder with a central axis;
a piston crown including a piston crown bowl with a central apex centered on the central axis and a curved base, where the piston crown bowl transitions from the curved base to a top surface of the piston crown through a curved transition having a transition radius, the piston crown bowl, sides of the cylinder, and a top of the cylinder forming a combustion chamber with a volume providing a compression ratio of 15:1; and
a central fuel injector that is operable to inject fuel directly into the combustion chamber, the central fuel injector including eight nozzle holes and positioned axially along the central axis and in a cylinder head of the cylinder, where outlets of the eight nozzle holes are symmetrically positioned around the central axis and along an outer circumference of a nozzle of the central fuel injector, each of the outlets having a common radius from the central axis, wherein the nozzle holes are symmetrically positioned around the central axis and along the outer circumference of the nozzle which is dome-shaped, wherein each of the nozzle holes has a K-factor of five, the K-factor defined as a difference between an inlet diameter and an outlet diameter of each of the nozzle holes, divided by a scaling factor of 10 microns, and wherein a tip of the nozzle has a height that is approximately half a diameter of the tip.
2. The combustion system of claim 1 , wherein the piston crown bowl is symmetric around the central axis, wherein a height of the central apex is the same as a height of the top surface of the piston crown, wherein the curved base is depressed below the height of the central apex and positioned symmetrically around the central apex, and wherein the central apex has a convex, spherical shape with an apex radius that is in a range of from 3 to 5 mm and the curved base has a concave shape with a base radius that is in a range of from 16 to 20 mm.
3. The combustion system of claim 1 , wherein the central fuel injector has a nozzle flow rate that is in a range of from 92 to 94 cm 3 /s at a pressure of about 10,000 kPa, the nozzle flow rate based on the eight nozzle holes and the K-factor of the nozzle holes and wherein the piston crown includes a central bore centered along the central axis and positioned below the central apex and void portions positioned around the central bore and below the piston crown bowl.
4. A combustion system, comprising:
a cylinder with a central axis;
a piston including a piston crown with a bowl, the bowl including a central apex centered along the central axis and a curved base, where the bowl transitions from the curved base to a top surface of the piston crown through a curved transition having a transition radius, the bowl forming a volume of a combustion chamber having a compression ratio of 15:1;
a central fuel injector for injecting fuel into the combustion chamber, the central fuel injector including eight nozzle holes and axially aligned along the central axis and positioned in a cylinder head of the cylinder, where each of the eight nozzle holes includes an outlet, and where outlets of the nozzle holes are symmetrically positioned around the central axis and along an outer circumference of a nozzle of the central fuel injector, each of the outlets positioned at a common radius on the outer circumference from the central axis; and
an exhaust passage without an aftertreatment system, wherein the exhaust passage does not include exhaust catalysts or particulate filters, wherein each of the eight nozzle holes has a K-factor of five providing an injector nozzle flow rate of 93.1 cm 3 /s at a pressure of about 10,000 kPa, the K-factor defined as a difference between an inner diameter and an outer diameter of each of the eight nozzle holes, divided by a scaling factor of 10 microns, and wherein the nozzle of the central fuel injector has a spray angle in a range of from 135 to 140 degrees defined by a position of opposite nozzle holes of the eight nozzle holes across the central axis.
5. The system of claim 4 , further comprising a controller including a microprocessor with instructions stored in memory to activate the central fuel injector to inject fuel into the combustion chamber to operate an engine in which the combustion system is installed to carry out combustion at the compression ratio of 15:1 and wherein a height of the central apex is substantially the same as a height of the top surface of the piston crown.