PECULIARITIES OF CALCULATION OF THE MAIN PARAMETERS OF THE WATER JET PROPULSION SYSTEM
DOI:
https://doi.org/10.32782/tnv-tech.2025.2.52Keywords:
Propeller, efficiency factor, parameter, limit values, design point, pressure, diameter, Bernoulli equation, fan, hydrodynamic scheme, ring, dimensions, reliability, efficiencyAbstract
A set of basic hydrodynamic parameters of the water jet propulsor is proposed. An analytical method for determining the optimal values of design parameters, at which the maximum efficiency of the propulsor is achieved, is given, as well as a method for calculating parameters other than hydrodynamically optimal, which expands the developer’s possibilities for optimizing the dimensions and mass of the propulsor. The key hydrodynamic parameters for water jet propulsor design are highlighted. The relationship between the hydrodynamic parameters of the water jet propulsor is shown. The meaning of the main hydrodynamic parameters is explained. The physical meaning of optimal values of hydrodynamic parameters is shown.The presented method of determining the limiting values of parameters at the design point is based on experimental studies, which makes it possible to establish the boundary of the area of existence of parameters of such propulsors. This method, together with the determination of optimal parameters by the value of the coefficient of efficiency and the same coefficient at suboptimal parameters, completes the problem of selecting the water jet propulsion’s design parameters. The method allows solving such important problems as creating a propulsor that develops maximum pressure at a given circular velocity, or a propulsor with minimum diameter but maximum static efficiency, etc. The methodology is based on the method of determining optimal and limiting design parameters using the Bernoulli equation. Definitions of basic hydrodynamic characteristics are given. The method of calculation by the method is shown on the example of the simplest case of the mover with one fan, when the diameters of the inlet and outlet channels are the same. The result of the calculations is illustrated graphically. The method of comparing design and experimental data of propulsors having different hydrodynamic schemes with equal and different design parameters allows for the revelation of the peculiarities of their characteristics and to apply in each specific case one or another scheme of the propulsor fan. The proposed method allows for the development of a propulsor for a watercraft under the given requirements for it, as well as to select a ready-made propulsor from the existing catalogs for a specific task of a watercraft. The features of calculating propulsors in the form of tubular axial fans with propellers in a ring are considered more efficient than propellers, allowing a gain in dimensions of a swimming vehicle. Besides, it is safer and more reliable in operation than a propeller.
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