During eight hours of PT-91 vehicle use, the  
Figure 1: Two-stage air filter with a multi-cyclone: (**a**) return cyclones with tangential inlet, (**b**) continuous cyclones, 1–cyclone, 2–dust trap, 3–cyclone mounting top plate, 4–cyclone mounting bottom plate, \(Q_{0}\)–inlet stream air, \(Q_{G}\)–outlet stream, \(Q_{S}\)–multi-cyclone suction stream. multi-cyclone filter, operating with 90% efficiency, can separate over 60 kg of dust, the storage of which requires a sedimentation tank with a capacity of over 25 dm\({}^{3}\). Storing a large dust mass in a multi-cyclone setter is not recommended due to the unnecessary load on the filter structure and the additional mass in the vehicle. The use of a large-capacity sludge trap increases the filter dimensions, which is especially undesirable for military vehicles. In addition, there are unfavorable phenomena:  
* During vehicle shocks and sudden changes in the engine speed: There are rapid changes in the air stream, which causes undesirable suction by the cyclone of dust accumulated in the settling tank,
* As a result of the settling tank completely filling: The dust does not settle in the settling tank, but it is entrained, and thus cyclone separation efficiency decreases. For this reason, in two-stage multi-cyclone air filters in vehicle engines used in areas of high dust concentration conditions in the air (tanks, infantry fighting vehicles, armored personnel carriers), systematic dust removal from the settling tank in a continuous manner is used. For this purpose, an additional air stream is used--the \(Q_{S}\) suction stream--and the phenomenon of ejection is used to create it. The \(Q_{S}\) flux value is obtained by using special fans or blowers driven by electric motors and powered by an on-board battery, which adversely affects the vehicle's energy balance. For this reason, in many air filter solutions for generating suction stream, appropriate ejectors that use the energy of the compressed air stream are used as a device for forcing the flow [17; 18; 19; 20] or exhaust gases out of the engine exhaust system [21; 22; 23]. Removal (by suction) of the separated and collected dust from the cyclone settling tank causes a noticeable increase in its separation efficiency, but only to a certain value of the suction degree--which usually does not exceed \(m_{0}=10\)-\(15\%\)[24; 25]. On the other hand, the available multi-cyclones design solutions analysis and their dust extraction systems from the settling tank, as well as the studies presented in [26], show that the connection of the dust discharge holes of several dozen cyclones into a common and tight space (dust settler) from which extraction takes place pointwise (with two or one stub pipe) and then causes different values (up to 50%) for the suction streams. In a multi-cyclone consisting of a large number (several dozen) of cyclones with a common dust trap, the use of only one or two dust extraction nozzles from the settling tank causes the outlet opening distances of the individual cyclones, which suction away from the extraction system stub, to be unequal. This naturally creates differences between the resistances in the flow and individual stream values that are sectioned out. This may have a negative impact on the proper operation of the multi-cyclone, as it reduces the separation efficiency of individual cyclones and, consequently, of the entire multi-cyclone. According to the author [27; 28], this phenomenon results from the uneven distribution of the air stream into individual cyclones, and even the reverse flow occurrence in the cyclones is located on the periphery of the multicyclone, which causes different characteristics in the adjacent cyclones. The highest suction stream values \(Q_{Sc}\) from individual cyclones occur, regardless of the value of the main suction stream from the \(Q_{SF}\) setting tank, for cyclones located closest to the dust suction nozzle of the settling tank.