Fuel Nozzle Spherical Lip Coanda Effect Spray Angle
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Solution Overview
Problem
Conventional fuel nozzles in gas turbine engines often fail to achieve a wide enough spray angle range, which is necessary for optimal combustion performance.
Innovation Solution
The design of a gas turbine engine fuel nozzle featuring a spherical distal end portion with an annular lip that utilizes the Coanda effect to increase the spray angle by causing the fuel jet boundary layer to attach to the annular surface, expanding the spray cone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conical shape fuel exit is used to achieve a specific spray angle, then the desired spray angle range is obtained, but a wider spray range cannot be achieved
Solution Approach 1:
The patent applies spheroidality by replacing the conventional conical fuel exit with a spherical distal end portion that has an annular lip curving away from the spray axis. This curved spherical geometry with a specific radius of curvature enables the fuel jet to follow the contour and achieve a wider spray angle range (75-105 degrees) while maintaining a relatively simple nozzle structure without complex adjustable mechanisms.
2Adaptability or versatility
If pressure atomization is used to achieve fuel spray, then combustion requirements are met, but spray angle control is limited
Solution Approach 1:
The patent changes the geometric parameters of the fuel exit passage, specifically implementing a spherical distal end portion with an annular lip having a constant radius of curvature (R) that is 0.5 to 2.0 times the exit orifice diameter. This parameter change in the exit geometry enables the fuel jet to attach to the curved surface via the Coanda effect, providing spray angle control within the 75-105 degree range without requiring complex adjustment mechanisms.
3Adaptability or versatility
If a spherical distal end portion with annular lip is used to widen spray angle, then spray angle increases to 105 degrees, but manufacturing complexity increases
Solution Approach 1:
The spherical distal end portion can be manufactured using standard spherical machining techniques or by incorporating a pre-formed spherical insert. The annular lip with constant radius of curvature is created through conventional machining or molding processes, making the design manufacturable with existing industrial capabilities while achieving the desired 75-105 degree spray angle range.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively widens the spray angle from 75 to 105 degrees, enhancing fuel mass distribution and combustion efficiency with minimal modifications to existing nozzle designs.
Implementation Method 1
exploiting the Coanda effect by causing a boundary layer of a jet of fuel discharged from a spray tip of the nozzle to attach to an annular outlet lip uniformly curving away from the spray axis around a full perimeter of a fuel exit passage of the spray tip
Data Source
AI summary
A gas turbine engine fuel nozzle comprises a spray tip defining a fuel exit passage therethrough that extends along a central axis. The fuel exit passage has an exit orifice aligned with the central axis. The exit orifice is circumscribed by an inner annular surface. The inner annular surface has a spherically-convex profile in cross-section, the profile being constant around the circumference of the inner annular surface.