- Author
-
Wood, C. B.
- Title
- Flow Simulation Through a Simplified Smoke Detector Using Computational Fluid Dynamics.
- Coporate
- Worcester Polytechnic Inst., MA
- Report
-
Thesis,
May 1995,
90 p.
- Keywords
-
smoke detectors
|
computational fluid dynamics
|
simulation
|
time lag
|
geometry
|
zone models
|
field models
- Identifiers
- effects of various underrelazation parameters; total flow through section across major direction at i=23; flow through detector section across major direction at i=23; flow through detector upstream face at i=12; flow thorugh upstream detector channel at k=7
- Abstract
- The lag-time in smoke detection due to smoke entry into a detector has been long recognized in the fire detection field. The details of the flow characteristics into and around a smoke detector is difficult to quantify experimentally. Computational Fluid Dynamics (CFD) provides a useful tool to perform such a task. The Fluent CFD model was used to simulate flow into and around a simplified smoke detector model. The effect of geometry of the detector on lag-time was examined by varying the internal geometry of the detector. The simulation was performed using the configuraion of the test section UL268 sensitivity test apparatus. This was done to (1) provide well-defined boundary conditions and (2) to demonstrate the concept of using CFD modelling for standard testing in the future. In the case of a detector in a duct flow, the average velocity across the duct varied from 180 mm/sec to 189 mm/sec for no detector through the most restrictive detector, respectively. The average mass flow per unit area within the detector dropped from 45.6 gm/sec-mm2 to 6.7 gm/sec-mm2 while the area dropped from 2.05E-03 to 1.66E-03 m2. Average velocities across the entire modelled space and within the detector varied by more than one order of magnitude in the extreme case. The CFD code simulated the increased obstructions in the flow field well.