Sprinkler Spray Characterization Using Laser Shadowgraphy and Data Compression
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Solution Overview
Problem
Existing fire suppression systems face challenges in accurately characterizing and modeling sprinkler spray performance due to limitations in early computational studies, which lack detailed knowledge of initial spray characteristics and dispersion predictions, leading to insufficiently accurate results for sprinkler performance evaluation.
Innovation Solution
A method combining laser-based Shadowgraphy/PTV measurements with basis function data compression to create a compact representation of sprinkler spray characteristics, enabling detailed near-field measurements and reducing computational requirements for spray dispersion analysis, integrated into a fire suppression design tool for improved accuracy and ease of use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If computational fluid dynamics (CFD) tools are used to model fire phenomena, then modeling capability is improved, but accuracy of sprinkler performance evaluation deteriorates due to lack of detailed initial spray characteristics
Solution Approach 1:
The patent performs preliminary experimental measurements of initial spray characteristics (drop size, velocity, spatial distribution) using laser-based PTV systems before conducting CFD simulations. This preliminary data collection and analysis enables accurate initialization of spray parameters in computational models, resolving the accuracy issue while maintaining automation benefits
Solution Approach 2:
The patent introduces an intermediary methodology that bridges experimental measurements and computational modeling. By using laser-based PTV measurements as an intermediate step to characterize spray properties, the system transfers accurate experimental data to CFD models, improving evaluation accuracy while preserving the advantages of automated computational analysis
2Measurement precision
If detailed near-field measurements of spray characteristics are conducted, then measurement precision is improved, but device complexity and computational requirements worsen
Solution Approach 1:
The patent extracts only the most critical spray characteristics (initial drop size distribution, velocity fields, spatial arrangement) from complex near-field measurements using laser-based PTV systems. By focusing on essential parameters rather than capturing all measurement data, the system achieves precise spray characterization while reducing computational burden and simplifying the overall system
Solution Approach 2:
The patent transforms complex spatial and temporal spray data into simplified parameter representations suitable for CFD initialization. By changing the form of data from detailed raw measurements to condensed spray parameters (drop size distributions, velocity moments, spatial correlations), the system maintains measurement precision while reducing computational complexity
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 approach provides a high-fidelity spray initiation database for consistent and widespread sprinkler dispersion analysis, enhancing the accuracy and efficiency of fire suppression system design and performance evaluation, aligning with regulatory code requirements.
Implementation Method 1
laser-supported Shadowgraphy/PTV (Particle Tracking Velocimetry) measurement techniques are used, where a pulsed laser beam is directed onto the initial spray
Implementation Method 2
a digital camera is focused on the initial spray. The pulsed laser and the digital camera actuation are synchronized to acquire double images of drops in the initial spray separated by a predetermined image separation time interval
Data Source
AI summary
An initial (near-field) spray generated by a sprinkler under study is fully characterized using a laser-supported Shadowgraphy/PTV system. Near-field spray characteristics are established from local measurements, which are mapped in a spherical coordinate system consistent with the kinematics of the spray. A novel data compression scheme is introduced to generate analytical functions describing the sprinkler spray based on the measurements. These analytical functions are useful for initiating the sprinkler spray in computational fluid dynamics (CFD) based spray dispersion and fire suppression modeling. The near-field spray measurements and associated data compression approach are validated by comparing volume density measurements 1 meter below the sprinkler with volume density predictions generated from spray dispersion calculations initiated with the analytical spray functions.