Abstract
Based on theoretical and practical studies into the causes of losses of propellers, caused by the axial inflows, employing the methods of computational fluid dynamics, we calculated the geometry of physical model of the thrusters with two degrees of freedom. We specified the required physical conditions of implementation, formalized geometric parameters of the model, assigned the initial and boundary conditions of differential equations that describe behavior of propeller flows in the recirculation zones. The coefficients are calculated that take into account the existence of degradation effects. The use of methods of computational fluid dynamics is necessary to account for the losses of propellers caused by the axial water inflows that are dependent on the degradation effects, which will contribute to reducing the propeller thrust and torque. As the result of the studies, we received the Reynolds and Froude numbers for the zero-velocity model of the ship: R n =4.405×106; F r =3.124. Components of the axial and tangential forces of the radial distribution of steering propellers thrusts are refined within the limits of 2.7–5.1 %. The largest deviation of similarity coefficients is in the region of 85–100 % of the rated propeller thrust. We obtained dependences of adjustment factors that affect the components of thrusts and torques proportional to the radius of propeller of the model and the actual steering propeller, related to the original geometry. The value of corrective factors depending on the propeller flow direction relative to the plane of motion of the ship is within the few hundredths of the percent. We systematized and compiled in the table the list of parameters (factors) according to the operating mode of the ship, which are required to solve the basic equations in the formalization of physical models of thrusters. The developed principles of formalization of the physical models of thrusters could be employed in the process of selection and improvement of design of combined propulsive complex and adjustment of selected regulators of components of the ship power plant.
Highlights
The development of coastal shelf of the world’s ocean, from the point of view of extraction of natural resources, the use of wind energy and current, has been going on at the very high rate
Sensitivity of ships power plants (SPP) of combined propulsive complexes c (CPC) to various losses depends on the types of propellers and engines, the use of various stabilizers in the design of the ship hull and the principles of change in control algorithms
By analyzing results for the open water at 100 % propeller rotation velocity, we found the following set of identification parameters of the physical model of steering propeller (SP) for maximum thrust: (a, b, n, m)*=(0; 0; 1.45; 0.06)
Summary
The development of coastal shelf of the world’s ocean, from the point of view of extraction of natural resources, the use of wind energy and current, has been going on at the very high rate. APSC of the type Azippul (depending on the type of the ships) are characterized by low resistance and high efficiency that combines the advantages of thrust of the propeller with the flexibility of using the drive of capacity from 900÷5000 kW (Fig. 2, b) Such SP are designed for velocities of up to 24 knots while maintaining excellent maneuverability, hydrodynamic and fuel efficiency, low level of noise and vibration. Sensitivity of ships power plants (SPP) of combined propulsive complexes c (CPC) to various losses depends on the types of propellers and engines, the use of various stabilizers in the design of the ship hull and the principles of change in control algorithms. This is especially true for the process of selection and improvement of different designs of CPC and the adjustment of chosen regulators
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