选取航空煤油的多组分表征燃料Jet-A world average(JW),运用大涡模拟和详细化学反应机理相结合的方法对该表征燃料的碳烟生成过程进行了数值模拟,从碳烟前驱物的生成、碳烟颗粒的生成及氧化等过程进行了详细预测。结果表明:Dalian碳烟...选取航空煤油的多组分表征燃料Jet-A world average(JW),运用大涡模拟和详细化学反应机理相结合的方法对该表征燃料的碳烟生成过程进行了数值模拟,从碳烟前驱物的生成、碳烟颗粒的生成及氧化等过程进行了详细预测。结果表明:Dalian碳烟模型可以较好地预测定容弹内多组分航空煤油表征燃料射流燃烧的碳烟的生长特性;对于描述碳烟生成的特征量,碳烟质量的增长略微滞后于颗粒数密度的增长;碳烟空间分布主要与当量比和温度的分布相关。当量比越小且温度越高的区域,碳烟生成量则越小。展开更多
Large eddy simulation(LES)is used to calculate the in-cylinder turbulent flow field in a direct injection spark ignition(DISI)engine.The computations are carried out for three different maximum valve lifts(MVL)and thr...Large eddy simulation(LES)is used to calculate the in-cylinder turbulent flow field in a direct injection spark ignition(DISI)engine.The computations are carried out for three different maximum valve lifts(MVL)and throughout 100 consecutive engine cycles.The simulated results as well as corresponding particle image velocimetry(PIV)measurement database are analyzed by the proper orthogonal decomposition(POD)method.Through a new developed POD quadruple decomposition the instantaneous in-cylinder flow fields are decomposed into four parts,named mean field,coherent field,transition field and turbulent field,respectively.Then the in-cylinder turbulent flow characteristics and cycle-to-cycle variations(CCV)are studied separately upon the four part flow fields.Results indicate that each part exhibits its specific characteristics and has close connection with others.The mean part contains more than 50%of the total kinetic energy and the energy cascade phenomenon occurs among the four part fields;the coherent field part possesses the highest CCV level which dominates CCV of the bulk flow.In addition,it is observed that a change in MVL affects significantly the in-cylinder flow behavior including CCV,especially for the coherent part.Furthermore,the POD analysis demonstrates that at least 25 sample cycles for the mean velocity and 50 sample cycles for the RMS velocity are necessary for obtaining converged and correct results in CCV.展开更多
文摘选取航空煤油的多组分表征燃料Jet-A world average(JW),运用大涡模拟和详细化学反应机理相结合的方法对该表征燃料的碳烟生成过程进行了数值模拟,从碳烟前驱物的生成、碳烟颗粒的生成及氧化等过程进行了详细预测。结果表明:Dalian碳烟模型可以较好地预测定容弹内多组分航空煤油表征燃料射流燃烧的碳烟的生长特性;对于描述碳烟生成的特征量,碳烟质量的增长略微滞后于颗粒数密度的增长;碳烟空间分布主要与当量比和温度的分布相关。当量比越小且温度越高的区域,碳烟生成量则越小。
基金supported by the National Natural Science Foundation of China(Grant Nos.51176020 and 51376029)
文摘Large eddy simulation(LES)is used to calculate the in-cylinder turbulent flow field in a direct injection spark ignition(DISI)engine.The computations are carried out for three different maximum valve lifts(MVL)and throughout 100 consecutive engine cycles.The simulated results as well as corresponding particle image velocimetry(PIV)measurement database are analyzed by the proper orthogonal decomposition(POD)method.Through a new developed POD quadruple decomposition the instantaneous in-cylinder flow fields are decomposed into four parts,named mean field,coherent field,transition field and turbulent field,respectively.Then the in-cylinder turbulent flow characteristics and cycle-to-cycle variations(CCV)are studied separately upon the four part flow fields.Results indicate that each part exhibits its specific characteristics and has close connection with others.The mean part contains more than 50%of the total kinetic energy and the energy cascade phenomenon occurs among the four part fields;the coherent field part possesses the highest CCV level which dominates CCV of the bulk flow.In addition,it is observed that a change in MVL affects significantly the in-cylinder flow behavior including CCV,especially for the coherent part.Furthermore,the POD analysis demonstrates that at least 25 sample cycles for the mean velocity and 50 sample cycles for the RMS velocity are necessary for obtaining converged and correct results in CCV.
