The use of co-simulation methodology in the project oF PZL SW-4 helicopter adaptation to maritime version

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Raczy?ski, R.
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The article will present issues related to the implementation of the HELIMARIS project that assume modernization of PZL SW-4 to maritime mission and landing on vessel. The project encompasses issues related with helicopter adaptation (passive and active elements increase crew safety) to maritime version, basing on the context of the multidisciplinary analysis philosophy. The CO-SIMULATION calculation methodology involves the use of CFD analyzes for calculations of helicopter aerodynamic characteristics, both during flight and landing approach to vessel deck. The calculation model is a mapping of the CAD geometry of the helicopter model with the built-in RR 250 C20R engine, taking into account simplifications aimed at limiting the number of elements. The issues presented in the article will focus on the aerodynamic analysis of the helicopter in the case of unintentional activation of the floats and the assessment of the impact on the helicopter static and dynamic stability depending on the flight phase and on the current configuration, as well as the problem of turbulence interference between vessel and the helicopter during the approach to landing. The use of CFD (figure 1) analyzes includes hydrodynamic aspect of helicopter buoyancy and vessel motion on waves and allows to describe the dynamics of phenomena occurring during flight of helicopter conducting operations in cooperation with vessels. The collected information will help to develop procedures for safe and optimal landing approaches on the vessel deck. The article also presents exemplary results of analyzes and attempts carried out so far as part of the implementation of the Helimaris project, as well as an approximation of issues related to the verification of tasks set based on real objects, adapted to perform maritime missions. The main aspect of modeling focuses on the assessment of aerodynamic characteristics of a helicopter equipped with an flotation system from point of view failure that can occur during flight and as result flotation system can be symmetric or antisymmetric activate. Maritime modification and nonintentional flotation system activation cause modification of aerodynamic characteristics that have influence on flight mechanics aspect of the static and dynamic stability of the helicopter, as well as to determine the swash plate control margin. The CFD analysis methodology with additional rotor model defined by VBM(Virtual Blade Model) User Define Function algorithms, will allow to determine the impact of disturbances of the active float system on the rotor performance and the possibility to trimming the rotor, also in the vicinity of the vessels deck. Another aspect analyzed based on the Co-Simulation philosophy is the use of CFD algorithms and equations describing helicopter flight mechanics, to assess the impact of aerodynamic disturbances generated by the vessel superstructures on the helicopter rotor during landing approach, including the case of symmetry and asymmetry inflow on to the rotor (taking into account the influence of vessel exhaust gases), as well as describe power and thrust fluctuation related with partially presence of the helicopter rotor above the vessel helideck. Analysis also including different environmental conditions depend on operation zone (for example Baltic Sea, Mediterranean Sea), that define boundary conditions velocity fluctuation. Definition of Turbulence (especially in the landing zone) related to the presence of a vessels that were determined based on tunnel tests and CFD analyzes, has been calculating by the CTO (Ship Design and Research Center), for sea states in accordance with the definition presented in Advisory Circular AC 27.801 (figure 2).