Patent Application
20200072129
The present disclosure relates to orifices for injectors, spray nozzles, and the like, and more particularly to discrete jet orifices such as used in fuel injectors for gas turbine engines.
A cylindrical bore is often used as a metering orifice for liquid or gas, such as in fuel injectors, spray nozzles, and the like. For example, U.S. Pat. No. 7,251,940 describes a fuel nozzle having a fuel shroud that defines a plurality of main fuel jets disposed offset from a central axis. Each of the main fuel jets is a cylindrical bore, which can issue a discrete jet of fuel for combustion in a gas turbine engine.
Improvements have been made to decrease the effects of manufacturing variability on spray orifices like the cylindrical bores described above. For example, certain inlet geometries can reduce the effects of manufacturing inconsistencies on flow through cylindrical bores, such as the inlet geometries described in U.S. Patent Application Publication No. 2014/0166143.
Even with manufacturing variability issue addressed as described above, there is still an inherent problem with the traditional cylindrical bore geometry. Namely there is inconsistent flow and/or pressure fluctuations and instability at certain points in a given flow curve, i.e., a curve of flow rates obtained as a function of pressure. For example, there is a hysteresis effect that causes cylindrical metering orifices to provide two different flow rates at a single given pressure, depending on whether the pressure is rising or falling. This inconsistency can lead to operational challenges that must be overcome in applications where precise flow control is required.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved flow consistency in cylindrical bores, metering orifices, discrete jet orifices, and the like. The present disclosure provides a solution for this need.
A nozzle tip includes a nozzle tip body defining an upstream surface and an opposed downstream surface. An outlet orifice is defined through the nozzle tip body for fluid communication from a space upstream of the upstream surface to a space downstream of the downstream surface. The outlet orifice includes a cylindrical outlet portion defining an outlet axis, and a tapered inlet portion upstream of the outlet portion. The tapered inlet portion converges down towards the outlet axis in a direction from the upstream surface toward the downstream surface.
The outlet orifice can be a first outlet orifice, wherein the nozzle tip body includes at least one additional outlet orifice similar to the first outlet orifice. The outlet axes of the outlet orifices can diverge away from a central longitudinal axis defined by the nozzle tip body to issue a diverging spray pattern. The tapered inlet can converge down toward the outlet axis at an angle less than or equal to 30° and greater than or equal to 10°. The tapered inlet portion can extend over half way along the length of the outlet orifice between the upstream surface and the downstream surface. It is also contemplated that the tapered inlet portion can extend over three-quarters of the way along the length of the outlet orifice between the upstream surface and the downstream surface.
The tapered inlet portion can meet the upstream surface at an orifice inlet edge with a circumference. The orifice inlet edge can define an obtuse angle between the tapered inlet portion and the upstream surface around the full circumference of the orifice inlet edge. The tapered inlet portion can extend from the orifice inlet edge to the cylindrical outlet portion.
A nozzle includes a nozzle body defining a feed passage. The nozzle also includes a nozzle tip as in any of the embodiments described herein. The upstream surface of the nozzle tip is in fluid communication with the feed passage of the nozzle body for supplying a flow of fluid to the outlet orifice.
The feed passage can include a flow passage that feeds into the outlet orifices that is annular or helical. A heat shield can be disposed downstream of the downstream surface of the nozzle tip, wherein an aperture is defined through the heat shield aligned with the outlet orifice to permit issue of fluid from the orifice therethrough.
A method of forming a nozzle tip includes forming a nozzle tip body with opposed upstream and downstream surfaces. The method includes forming a plurality of outlet orifices through the nozzle tip body on respective orifice axes that are angled diverge away from a central longitudinal axis in a downstream direction, each outlet orifice including a cylindrical outlet portion and a tapered inlet portion upstream of the cylindrical outlet portion. Forming each outlet orifice can include forming the tapered inlet portion with an EDM tool extending through the cylindrical outlet portion. It is also contemplated that forming each outlet orifice can include forming the tapered inlet portion in a downstream portion of the nozzle tip body with a cutting tool extending from an upstream position along an orifice axis, followed by joining the downstream portion of the nozzle tip body to an upstream portion of the nozzle tip body so that the upstream portion of the nozzle tip intersects the orifice axis.
These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings.
So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures, wherein:
Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of a nozzle tip in accordance with the disclosure is shown in
Injector 10 includes a feed arm 12 and a nozzle 14 includes a nozzle body 16. Nozzle body 16 defines a feed passage 18 that is in fluid communication with passage 20 through feed arm 12 to supply fluid to issue from nozzle 14. Nozzle 14 also includes a nozzle tip 100. The upstream surface 102 (identified in
Referring again to
With reference now to
The outlet axes of the outlet orifices diverge away from a central longitudinal axis A defined by the nozzle tip body 108 to issue a diverging spray pattern. The tapered inlet 112 converges down toward the outlet axis at an angle α less than or equal to 30° and greater than or equal to 10°. The tapered inlet portion meets the upstream surface at an orifice inlet edge 114 with a circumference. The orifice inlet edge 114 of each outlet orifice 104 defines an obtuse angle θ between the tapered inlet portion and the upstream surface around the full circumference of the orifice inlet edge 114.
With continued reference to
With reference now to
Were a tapered inlet orifice to have a taper that extends all the way to the downstream surface, the tapered outlet would form a sharp edge at the downstream surface. Such sharp edges can be the cause of considerable manufacturing variability. This is detrimental to metering orifices, since if multiple metering orifices have different effective diameters due to manufacturing variability, the flow rates through the different orifices will vary considerably from the intended flow rate. Cylindrical outlets like cylindrical outlet portions 110 relieve this manufacturing variability, and allow for orifices 104 to serve as metering orifices with little or no manufacturing variability impacting flow rates. When these cylindrical outlet portions 110 are used in combination with tapered inlet portions 112, the benefits of tapered passages are added to the benefits of cylindrical outlets. In particular, the hysteresis effects described above for purely cylindrical metering orifices can be reduced or eliminated, while also reducing or eliminating the issues of manufacturing variability in tapered orifices.
The methods and systems of the present disclosure, as described above and shown in the drawings, provide for discrete jet orifices with superior properties including consistent flow rate as a function of pressure regardless of whether pressure is increasing or decreasing. While the apparatus and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.
This is a divisional of U.S. patent application Ser. No. 15/003,561 filed Jan. 21, 2016, the content of which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15003561 | Jan 2016 | US |
| Child | 16676855 | US |
