Analysis Of The Engine Inlet Temperature Distortion In Shipboard Environment

The jet fighter,since as the carrier aircraft,faces harsher working conditions than the land based fighter,and the carrier aircraft particularly its engine is required for higher demand.Temperature distortion of the inlet of the carrier aircraft can be caused by exhaust backflow due to the deflector of the aircraft carrier and the high-temperature steam leaking from the steam ejection,thus threatening the use of the aircraft carrier and its fighting capacity.Therefore,the study on temperature distortion of the inlet of the carrier aircraft under complex shipboard conditions is of great significance.The first part mainly considers the problems to the carrier aircraft under certain shipboard conditions by means of data collection and literature search.Modeling of the foredeck of the aircraft carrier and its jet blast deflector(JBD)is made via data.Simplification process is made for the original aircraft carrier model so as to save calculation resources and simulation time.Boundary conditions required for the subsequent simulation are confirmed,including atmospheric environment of the shipboard,wind field,process of the steam ejection and its launch time and performance etc.The structured grid is divided for the ship model and the simplified model of the aircraft carrier,and the simulation solution of CFD data is confirmed.The second part studies the effect of exhaust backflow on the temperature distortion of the carrier aircraft's inlet temperature distortion in stationary state.Firstly,simulation analysis is made with the angle of JBD for 55 degrees,angle of deflection for 0 degree and the layout of exhaust nozzle for a distance of 4.0 meters.Then the form and mechanism of exhaust backflow is obtained.Secondly,effects of exhaust nozzle distance,angle of JBD,angle of deflection,temperature,deck wind and working state of exhaust nozzle on exhaust backflow is studied via the control variate method.And finally,three kinds of JBD and the process of exhaust backflow under the layout of the exhaust nozzle are compared.Results show that exhaust backflow caused by the JBD is similar to the hot fountain,in which exhaust backflow and the resultant temperature distortion can be eliminated by a decrease of JBD angle and an increase of deflection angleThe third part studies the effect of indraft of the steam leakage on temperature distortion of the inlet in stationary state.Indraft of the steam only is firstly studied,and results show that the increased temperature caused by indraft of the steam only is 15 K,and the maximum circumferential unevenness is 0.7%,indicating that steam leakage causes little temperature distortion.Then,effects of exhaust backflow and steam coupling on the inlet are studied for three kinds of coupling time.Results show that exhaust indraft can reduce the steam in the inlet,and the circumferential unevenness due to the coupling of exhaust backflow and steam coupling reaches 15%,which is higher than 7.8% with exhaust indraft only.The fourth part studies effects of indraft of exhaust backflow,steam leakage and the coupling of exhaust and steam on temperature distortion of the inlet under the ejection motion.Results show that exhaust backflow can result in high-temperature zone in front of the carrier aircraft;when the carrier aircraft in ejection motion passes through this zone,the temperature of the inlet,circumferential unevenness and the exhaust content shall firstly increase and then decrease,and the maximum circumferential unevenness is 5.15%;indraft of steam leakage under the motion state also shows an increase first,then decrease for the vapor content,and the corresponding maximum circumferential unevenness is 0.556%.