RESEARCH ON THE HYDRODYNAMIC AND STRUCTURAL RESPONSE CHARACTERISTICS OF COMPOSITE PROPELLERS BASED ON SIMILARITY CRITERIA

In order to predict the hydrodynamic characteristics of a composite propeller, dimensional analysis was applied to systematically examine the parameters affecting propeller hydrodynamic performance. Hydrodynamic similarity models specifically tailored for the composite propeller were developed based on similarity criteria. A bidirectional fluid-structure coupling computational method was implemented to comparatively analyze the hydrodynamic performance, structural responses, and vibration modal characteristics between prototype and model propellers. The results indicate that the required inflow velocity of the model propeller, based on the Reynolds similarity criterion, must be significantly higher than that of the prototype, making it difficult to achieve under conventional experimental conditions. This suggests that the Reynolds similarity model is unsuitable for predicting the hydrodynamic performance of the composite propeller. Under the Froude similarity criterion, it is theoretically required that the model propeller maintain identical material density to the prototype while simultaneously reducing elastic and shear moduli by factors proportional to scaling ratios. Given the practical limitations in material manufacturing that prevent concurrent fulfillment of these dual requirements, two non-standard Froude similarity models were developed by relaxing the criterion. In the Froude similarity model with relaxed elastic properties, the model propeller exhibits greater stiffness, resulting in measurable deviations in hydrodynamic performance compared to the prototype. In the Froude similarity model with relaxed density requirements, the hydrodynamic performance of the model propeller aligns well with the prototype, though minor discrepancies persist in the modal frequency matching. The results based on the Mach similarity criterion show good agreement between the prototype propeller and the model in terms of hydrodynamic performance, structural response, and vibration modes. This demonstrates the applicability of the Mach similarity model for predicting the performance of the composite propeller prototype. The hydrodynamic similarity relationship between the prototype and model is established, providing crucial theoretical foundations for design optimization processes of composite marine propellers.