Investigation findings of a packaged bilevel rafting unit stationary motion in water. <i>I</i>
Forming of bilevel packaged rafting units (BPRU) of round wood is feasible at areas of inflow of small rivers to the larger ones. Forming of the BPRUs at the winter log storage and bundling areas is preferable in cases of cut-to-length logging in relatively small volumes, when usage of special log bundling machinery is unfeasible. Application of BPRU creates conditions for eco-friendly and economic transportation of wood raw material. Engineering valuations of BPRU are based on information concerning water resistance to stationary motion of a body. The topic analysis showed reasonability of the investigation. The factors of water resistance to stationary motion of BPRU were educed theoretically. The derived dependence was transformed to dimensionless form. Based on the theory of the subject, two factors were excluded: the relative wood density and the Reynolds number. As a result, the symbolic description was presented as a dependence of water resistance coefficient on the BPRU shape coefficient, length/height relation and the Freud number. Based on the criterial solution, the experimental studies were performed using models of quadric B-plan under condition of correspondence of derived criteria in the model and natural conditions. The regression models of lengthwise and transverse motion of a BPRU were worked out. These models make possible to determine a water resistance force using the Newton formula. The review of the models indicated that the named factors affect more significantly during the transverse motion. The Freud number increase contributes to enlargement of a resistance coefficient. Influence of the shape coefficient is dependable on other factors, including relative length. The impact rate of the factors, as the rule, depends on the value of other factors.