The influence of multi - role aircraft mission type on the low bypass engine performance parameters

The aim of the article is to find the relationship and dependencies between the mission parameters of the multi-role aircraft (altitude, flight velocity, thrust load) and the parameters that define the flow of the turbofan engine. The conclusions of these studies are relevant at the stage of preliminary engine design. There was built the model of thermal cycle of low bypass. The model of an airplane was simplified to its aerodynamic characteristics. The mission was divided into air tasks (stages) such as a take-off, a climb at a certain velocity, sub and supersonic flight and maneuvers (i.e. turn). Dimensionless energy criteria binding both the engine and aircraft parameters were introduced. There were conducted the simulation studies of the model airplane-engine mission to show the part of the mission that "dimensions " the engine. The results were limited to the presentation of the impact of circuit parameters such as T3, π, μ on the defined criteria. The calculations were carried out for a number of selected missions defined in the literature as Loll, HiLoHi and HiHiHi. The comparison of the energy requirements of these missions was done. There were pointed out these criteria of the mission evaluation that may affect making decisions at early design stages. There were designated the areas of design variability in an engine meeting the criteria for energy mission. The advantage of this model is universal character of dimensionless criteria, whereas the disadvantage is the need to build complex models of the engine and the assumption at the outset aerodynamic characteristics of the aircraft. The originality of the presented solution is to show an alternative, unconventional approach to the design process (not as so far) the engine itself but the entire aviation system.