翼身融合民机背撑发动机安装效应对推力影响研究

针对背撑发动机布置的翼身融合布局(Blend wing body,BWB)民机,为了研究机体对发动机周围流场的干扰和安装效应对有效推力的影响,通过对单独发动机短舱和飞机-发动机安装状态三维流场进行数值模拟,采用推阻力划分方法提取安装和非安装状态下发动机推阻力相关参数,获得了巡航状态和低速12°迎角状态下发动机安装效应对背撑式BWB民机推力的影响规律。结果表明:高速巡航状态,机体对发动机表面压力分布的影响导致短舱外表面吸力降低,发动机阻力增大是造成有效推力损失的主要原因;低速12°迎角状态,内、外涵喷流受机体流动影响压力降低,引起内推力减小,其降低量占有效推力安装效应影响的比例约95%,且机体边界层和分离流动并未影响发动机进气品质。在背撑式BWB民机设计中,需要考虑不同飞行状态下BWB机体对安装状态发动机流场的干扰,减小安装效应对有效推力的影响。

Investigation of Engine Installed Effect on Thrust of Blended Wing Body Transport with Podded Engines

To investigate the airframe flow interaction on flowfield around engine nacelles and the in-stalled effect on effective thrust of the Blend Wing Body (BWB) transport with podded en-gines, the numerical method was applied to simulate the three-dimensional flowfield of the isolated and installed configuration. The thrust and drag related parameters of the isolated and installed nacelles were obtained by the thrust drag bookkeeping. The influence of engine installation effect on thrust components of the podded BWB transport was achieved at cruise and low speed condition with 12° angle of attack. The results indicate that the major reason for effective thrust loss at cruise condition is the increment of nacelle drag due to the reduc-tion of suction force on the nacelle external surface. At low speed condition with 12° angle of attack, the decrease of pressure at fan and core nozzle exit causes the reduction of installed net thrust, which accounts for about 95% of the effective thrust loss. Meanwhile, the quality of engine intake flow is not affected by boundary layer flow and separation flow. In the de-sign of podded BWB transport, the interference of airframe on installed nacelle should be taken into account at different flight conditions to reduce the influence of installed effect on effective thrust.