Selective catalytic reduction (SCR) systems rely on urea-based reagents, which must be regularly refilled, increasing operational costs, and their performance declines in low ambient temperatures [38; 39]. Oxidation catalysts (DOC) offer limited effectiveness in reducing particulate matter (PM) and nitrogen oxides and are sensitive to fuel quality [40; 41]. Combined systems integrating SCR and DPF provide high filtration efficiency but inherit the cost and operational drawbacks of both technologies [42; 43]. The existing drawbacks of current methods and technologies not only fail to fully resolve the environmental challenges of diesel engines but also hinder design simplicity and reduce the overall system efficiency. Therefore, there is an urgent need to develop alternative and more effective methods for reducing exhaust smoke, which can complement or replace existing cleaning systems. One promising direction is the use of physical methods to influence the exhaust gas flow, such as ultrasonic treatment. Several studies have been conducted in the field of ultrasonic exhaust gas purification for vehicles, particularly focused on the development of ultrasonic mufflers designed to neutralize harmful components of diesel engine emissions [43; 44; 45; 46; 47]. These mufflers employ ultrasonic vibrations to reduce the concentration of PM and other toxic particles by promoting the coagulation of fine particles and facilitating their deposition. This method reduces exhaust smoke, lowers the load on conventional emission control systems such as DPF and SCR, and improves the overall efficiency of diesel emission treatment without significantly increasing the exhaust backpressure. The experimental results from these studies confirmed the effectiveness of ultrasonic treatment in reducing concentrations of CO\({}_{2}\), CO, and hydrocarbons while increasing the oxygen content in exhaust gases [43; 44; 47]. However, all of these investigations were based on horizontal-type experimental mufflers, which present several limitations. One key drawback is the limited gravitational assistance for particle deposition of coagulated particles in a horizontal flow path, leading to their continued suspension and reduced overall purification efficiency. In such systems, achieving uniform ultrasonic exposure is difficult due to linear gas flow, which may allow some particles to bypass treatment before they exit the muffler. Moreover, horizontal designs limit emitter placement, reducing the feasibility of multi-stage treatment and restricting the gradual agglomeration and removal of PM. Smaller particles that fail to agglomerate remain in the exhaust stream and are ultimately released into the atmosphere. Additionally, horizontal systems are more susceptible to internal clogging due to uneven particle distribution along the walls, which increases flow the resistance and decreases the system efficiency. To overcome these limitations, this study proposes the development of a vertical ultrasonic muffler system, in which gravity assists in the downward deposition of coagulated particles, increasing the efficiency of solid particle capture at the bottom of the unit. A vertical layout also enables the integration of multiple ultrasonic emitters in a stepwise configuration, allowing for staged exhaust gas treatment and more effective removal of fine particles. The central hypothesis of this research is that a vertical ultrasonic muffler, with optimally positioned and powered emitters, can effectively reduce exhaust smoke from diesel engines by promoting the coagulation of fine particles. Adjusting the emitter power and spacing in accordance with the engine operating conditions will lead to a significant reduction in the smoke density. The aim of the study is to design and experimentally evaluate a vertical-type ultrasonic muffler capable of reducing the smoke content of diesel engine exhaust and to optimize its operational parameters.