Non-Destructive Fog Dissipation System

Abstract

While technological advancements have undoubtedly empowered humans to surmount countless challenges, they have not entirely eradicated the influence of weather on human life. Certain weather conditions, such as fog, can significantly impede human activities and result in substantial losses. Reduced visibility caused by fog contributes to significant financial and human losses annually. Fog, a natural phenomenon occurring frequently in various regions worldwide, often persists for extended periods. This necessitates the development of solutions to mitigate its impact. Over the decades, researchers have extensively experimented with fog and devised numerous methods to address this challenge. While efforts to disperse supercooled fog have yielded some success, eliminating warm fog remains a challenging endeavor. Existing techniques for warm fog dispersion are often impractical, costly, or associated with significant environmental impacts. Therefore, this thesis endeavors to explore an innovative solution to this problem—one that is inexpensive, straightforward, and has no adverse effects on the environment (i.e., nondestructive).

Two proposed methods offer potential solutions to address this challenge. The first method involves utilizing waves in the radio frequency range. This approach aims to induce a resonance effect in the fog particles, potentially leading to improved visibility. The second method involves applying sound waves directly at the fog layer. While the concept itself is not novel, this study introduces a novel approach by examining the impact of adding harmonics on enhancing visibility during fog conditions. This aspect has not been previously investigated, adding a unique dimension to the research. After evaluating both methods, it was determined that the first method was significantly more expensive compared to the second method. Therefore, this study opts to adopt the second method as the preferred approach. To investigate the influence of sound waves on enhancing visibility in fog, an experimental setup was arranged. This setup encompasses sensors, a fog chamber, a fog-generating machine, and a sound system. Initial tests concentrated on single frequencies, with a particular focus on frequencies previously reported in the literature as optimal for enhancing visibility. Subsequent tests involved adding harmonics to a subset of these fundamental frequencies.

When sound waves were applied at a single frequency and constant SPL (112 dB), 300 Hz was observed to yield the best dissipation effect. Additionally, a trend emerged, revealing that higher frequencies had a more pronounced effect on smaller droplets and vice versa. Notably, the most significant impact under varying SPLs occurred when sound was applied at frequencies of 528 Hz at 118 dB, 600 Hz at 120 dB, and 1000 Hz at 105 dB. This effect was achieved by reducing the number of large droplets which have a higher LWC compared to smaller droplets. Droplets collide under the influence of sound waves and coalesce into larger droplets, eventually descending. Additionally, it was observed that the number of small droplets increased with the application of sound waves. This phenomenon is presumed to be attributed to the fragmentation of some of the large particles. The analysis of data obtained from the application of sound at various fundamental frequencies with their harmonics revealed that the majority of the harmonics investigated did not contribute to improving visibility. However, an exception was observed with the application of sound waves at 400 Hz when paired with its 9th harmonic. Utilizing this combination produced a notably improved visibility compared to using 400 Hz alone. Moreover, it demonstrated performance equal to, or even surpassing, the previously selected frequencies with the most pronounced condensation effect. It resulted in a 61.06% reduction in the LWC for large droplets with minimal increase for smaller ones. Additionally, it achieved a 90% condensation effect in a shorter time than natural fog dissipation, cases involving sound application at the fundamental frequency, and all other cases involving harmonics. These results emphasize the potential of employing harmonics for acoustic fog elimination. However, further research encompassing a broader range of frequencies and harmonics is necessary to identify the most effective combination.

Date of Award	7 May 2024
Original language	American English
Supervisor	REYAD El Khazali (Supervisor)