Spray Mist Nozzle Outlet Geometry for Stable High-Pressure K-Factor

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Solution Overview

Problem

Existing spray mist nozzles exhibit variations in the K-factor at high operating pressures, leading to unpredictable and unstable discharge behavior, particularly at pressures above 30 bar and K-factors below 1.0, which affects the reproducibility and effectiveness of firefighting systems.

Innovation Solution

The nozzle design incorporates a convexly curved transition from the minimum opening cross section to the exit cross section, along with a widened incident-flow cross section, to stabilize the K-factor and enhance discharge consistency, utilizing a swirl body to swirl the extinguishing fluid before exit, ensuring a homogeneous spray mist with both fine and larger droplets for improved casting distance and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a spray mist nozzle is designed with a conventional outlet geometry, then the manufacturing is simpler, but the K-factor becomes unstable at high operating pressures above 30 bar

Engineering Contradiction:

ImproveK-factor stabilityVSAvoidoutlet geometry complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies curvature by designing the outlet geometry with a convexly curved surface instead of a straight or angular transition. Specifically, the outlet includes a convexly curved surface extending from the minimum opening cross-section to the exit cross-section, which stabilizes the K-factor at high operating pressures by creating a more favorable flow pattern and reducing turbulence effects

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Length of moving object

If the spray mist outlet has a larger exit cross section, then the casting distance increases, but the atomization effect decreases

Engineering Contradiction:

Improvecasting distanceVSAvoiddroplet homogeneity

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The patent applies local quality by creating different cross-sectional areas at different locations along the outlet. The outlet geometry features a minimum opening cross-section followed by a convexly curved expansion to a larger exit cross-section. This local variation in geometry allows the fluid to maintain atomization quality near the minimum cross-section while achieving extended casting distance at the expanded exit

Inventive Principle:

Principle #3Local quality

3Length of moving object

If the spray mist nozzle operates at high pressure above 30 bar, then the casting distance increases, but the K-factor becomes unpredictable

Engineering Contradiction:

Improvecasting distanceVSAvoiddischarge behavior consistency

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The convexly curved surface in the outlet geometry stabilizes the flow at high pressures by creating a gradual expansion that reduces flow separation and turbulence. This curved geometry maintains predictable discharge behavior and stable K-factor even when operating at pressures above 30 bar, enabling extended casting distance without sacrificing reliability

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Manufacturing precision

If the spray mist outlet has a minimized opening cross section, then the atomization effect is maximized, but the exit cross section is reduced

Engineering Contradiction:

Improveatomization qualityVSAvoidexit cross section area

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The convexly curved expansion connects the minimized opening cross-section to a larger exit cross-section, allowing the fluid to maintain the high-velocity atomized flow generated at the minimum cross-section while expanding into a larger area downstream. This curved transition preserves atomization quality while achieving greater exit area for extended casting distance

Inventive Principle:

Principle #14Spheroidality (Curvature)

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

The design achieves a significantly more stable K-factor, ensuring consistent discharge behavior and enhanced casting distance while maintaining a homogeneous spray mist, even at high operating pressures.

Implementation Method 1

an exchangeable swirl body (31) arranged in the main body (29) and configured to swirl the extinguishing fluid prior to the latter exiting from the spray mist outlet (39)

Methodology Applied

Scientific EffectVortex flow: Vortex Ring

Data Source

PatentUS12491523B2Spray mist nozzle for fire-fighting systems, and fire-fighting systems having same

Publication Date: 2025.12.09 MINIMAX VIKING PATENT MANAGEMENT GMBH

AI summary

The invention relates to a spray mist nozzle, in particular an open high-pressure spray mist nozzle for firefighting systems, having a housing which is configured with an extinguishing fluid inlet and is configured with multiple recesses for receiving an exchangeable nozzle insert, such a nozzle insert being inserted into one, multiple/plural or all the recesses. The nozzle insert has a main body with a longitudinal axis that has in the longitudinal axis a spray mist outlet for the extinguishing fluid. An exchangeable swirl body is arranged in the main body and is configured to swirl the extinguishing fluid prior to the latter exiting from the spray mist outlet. The spray mist outlet has a minimum opening cross section, and has a widened exit cross section downstream of the minimum opening cross section, wherein a transition from the minimum opening cross section to the exit cross section runs along a convexly curved surface.