Research On Modeling And Control Of Propfan Engines

Propfan engines have high propulsive efficiency and have the potential to reduce fuel consumption and emissions,which have a promising future because of the huge civil aviation market in the future and the more and more requirements of environmental protection.However,the novel engine presents many challenges of structural design,control strategy and engine-aircraft integration.The modeling and assessment of propfan engine is beneficial for the optimum structural design and control strategies for engine-aircraft integration,which makes full use of propfan engines.A simulation model of three-shaft contra-rotating puller propfan was proposed.Propfan engine was considered as a matching with propfan and turboshaft.Propfan model,based on the similitude principle,starts with the aerodynamic performance for a single rotating propfan.The influence of hub,the interaction of contra-rotating propfans and the contraction of stream are all considered.Error of the model and the experimental results is no more than 2%.The control scheme of propfan engine is different from those of turbofan engines,for the thrust of propfan engines is mainly produced by propfans.Performance seeking control benefits propfan engine by generating optimal performance in different flight status.After analysing the control structure of propfan engines,a control scheme for the propfan engine is proposed.The control scheme works well in flight envelope and the simulation results show that the overshoot of power shaft rotation speed is less than 2% and the settling time is less than 0.9s.Based on this,a control scheme in performance seeking mode is proposed.A Modified Cuckoo Search method,which modifies the search step size and abandonment rate,is applied in the control scheme in maximum thrust mode and minimum fuel flow mode.The control scheme in performance seeking mode can reduce 2% fuel flow,compared with the control scheme in torque-compensation mode.Performance of the scheme is better than standard Cuckoo Search and Genetic Algorithm.Assessments are conducted based on the simulation model.According to the assessments,the pitch angles of propfans have a great impact on propfan engine performance and they are important regulative parameters for engine performance.The propfan-inlet interaction has a little influence on performance and could be ignored.The wheelbase of contra-rotating to radius ratio could be set up from 0.4 to 0.6.When the numbers of front and apt propfans become larger,the thrust and the SFC will become larger while the efficiency of propfan will become smaller.The speed and altitude response of propfan engine is also presented.