New high-speed imaging method captures 3D details of combustion flames

Researchers have developed a brand new methodology for capturing the complicated habits of turbulent flames produced throughout combustion. Insights supplied by this high-speed 3D imaging strategy could possibly be used to develop extra environment friendly and cleaner combustion techniques for automobiles, airplanes, factories and energy vegetation.

“The high-speed imaging strategy we developed offers detailed insights into flame dynamics, ignition processes and combustion habits,” mentioned Qingchun Lei from Northwestern Polytechnic College in China. “This may present insights into combustion effectivity, pollutant emissions and the optimization of vitality manufacturing processes that could possibly be used to enhance the design and operation of energy vegetation, engines, and different combustion units, resulting in lowered environmental influence and enhanced vitality effectivity.”

In Optics Letters, the researchers describe their new method which provides high-speed picture reconstruction and 3D info to schlieren imaging, a well-established method for imaging and measuring phenomena in fluids. The brand new methodology can be utilized to quantitatively acquire the 3D density and velocity distribution of turbulent flames.

“The detailed understanding of flame habits and ignition processes facilitated by this system also can contribute to simpler fireplace security measures by offering info on how fires unfold, develop and might be suppressed,” mentioned Lei. “This can be utilized to reinforce fireplace prevention methods, enhance constructing designs and develop extra environment friendly fireplace suppression techniques that might in the end assist save lives, shield property and enhance total fireplace security requirements.”

Including pace and a number of views

As a result of turbulent combustion is extremely dynamic and 3D in nature, it's tough to quantitatively seize it sufficiently utilizing measurement strategies akin to conventional schlieren imaging. To resolve this drawback, the researchers mixed three imaging strategies: fiber imaging, schlieren imaging and computed tomography (CT).

The brand new method makes use of a sequence of fiber bundles to transmit mild containing flame info from completely different angles. Every angle of sunshine rays types a Toepler’s lens-type schlieren system that may picture the density variations of the goal flames. CT, which is usually utilized in medical imaging, is then employed to reconstruct the 3D schlieren pictures. Lastly, post-processing of the 3D schlieren pictures is used to acquire 3D density and velocity info.

“Fiber imaging permits high-speed, simultaneous schlieren imaging from a number of views in a versatile and cost-effective method whereas including CT permits the 3D reconstruction of goal flames primarily based on the multi-angular 2D pictures,” mentioned Lei. “The ensuing high-speed 3D schlieren imaging method achieves a body price past tens of kHz, which permits the seize of quickly altering flame phenomena with distinctive temporal decision, offering detailed insights into transient flame occasions.”

Capturing complicated flame dynamics

To validate the effectiveness and efficiency of the high-speed 3D schlieren imaging strategy, the researchers performed experiments on turbulent and laminar premixed flames in addition to transient ignition processes. The experimental setup included a single high-speed digital camera, two Xenon lamps and a sequence of fiber bundles.

The fiber bundles had been positioned to seize schlieren pictures of the flames from seven completely different orientations concurrently whereas the digital camera recorded the photographs at a excessive body price. The experimental setup is comparatively inexpensive in comparison with extra complicated and specialised tools, akin to lasers, utilized in different methods.

The outcomes of the experiments confirmed that the high-speed 3D schlieren imaging strategy efficiently captured and measured the flame dynamics, construction and ignition processes.

The researchers are actually working to reinforce the method’s practicality and potential for commercialization. This consists of testing its robustness and reliability throughout a broader vary of flame circumstances and configurations in addition to optimizing the picture processing and reconstruction algorithms. Additionally they wish to enhance system integration and automation and additional simplify the setup.