**Figure 1.**
Schematic diagram of dynamic electromagnetic scattering of a biaxial turbofan engine.

**Figure 1.**
Schematic diagram of dynamic electromagnetic scattering of a biaxial turbofan engine.

**Figure 2.**
Verification of the dynamic scattering method (DSM) with m_{fan}, β = 0°, and f_{R} = 6 GHz.

**Figure 2.**
Verification of the dynamic scattering method (DSM) with m_{fan}, β = 0°, and f_{R} = 6 GHz.

**Figure 3.**
Geometric configuration of a turbofan engine with full factorial design (FFD).

**Figure 3.**
Geometric configuration of a turbofan engine with full factorial design (FFD).

**Figure 4.**
Model building and detail display of the turbofan engine.

**Figure 4.**
Model building and detail display of the turbofan engine.

**Figure 5.**
Surface mesh distribution of various components of the turbofan engine.

**Figure 5.**
Surface mesh distribution of various components of the turbofan engine.

**Figure 6.**
Surface scattering distribution of the fan, α = 0°, β = 0°, and f_{R} = 6 GHz; RCS unit: dBm^{2}.

**Figure 6.**
Surface scattering distribution of the fan, α = 0°, β = 0°, and f_{R} = 6 GHz; RCS unit: dBm^{2}.

**Figure 7.**
Influence of observation time on dynamic RCS of m_{fan}, α = 20° and β = 0°.

**Figure 7.**
Influence of observation time on dynamic RCS of m_{fan}, α = 20° and β = 0°.

**Figure 8.**
Influence of observation time on dynamic radar cross-section (RCS) of m_{low}, α = 160° and β = 0°.

**Figure 8.**
Influence of observation time on dynamic radar cross-section (RCS) of m_{low}, α = 160° and β = 0°.

**Figure 9.**
Influence of azimuth on dynamic RCS of m_{fan}, N_{obs,fan} = 1 and β = 0°.

**Figure 9.**
Influence of azimuth on dynamic RCS of m_{fan}, N_{obs,fan} = 1 and β = 0°.

**Figure 10.**
Influence of azimuth on dynamic RCS of m_{fan}, α = 320°~360°, N_{obs,fan} = 1, and β = 0°.

**Figure 10.**
Influence of azimuth on dynamic RCS of m_{fan}, α = 320°~360°, N_{obs,fan} = 1, and β = 0°.

**Figure 11.**
Influence of azimuth on dynamic RCS of m_{low}, N_{obs,low} = 1, α = 150°~210°, and β = 0°.

**Figure 11.**
Influence of azimuth on dynamic RCS of m_{low}, N_{obs,low} = 1, α = 150°~210°, and β = 0°.

**Figure 12.**
Influence of elevation angle on dynamic RCS of m_{low}, N_{obs,low} = 1 and β = (0, 10, 20)°.

**Figure 12.**
Influence of elevation angle on dynamic RCS of m_{low}, N_{obs,low} = 1 and β = (0, 10, 20)°.

**Figure 13.**
Influence of elevation angle on dynamic RCS of m_{low}, N_{obs,low} = 1 and β = (0, 10, 20)°.

**Figure 13.**
Influence of elevation angle on dynamic RCS of m_{low}, N_{obs,low} = 1 and β = (0, 10, 20)°.

**Figure 14.**
The dynamic RCS of m_{fan} + m_{duct}, N_{obs,fan} = 1, α = (0~40 and 320~360)°, and β = 0°.

**Figure 14.**
The dynamic RCS of m_{fan} + m_{duct}, N_{obs,fan} = 1, α = (0~40 and 320~360)°, and β = 0°.

**Figure 15.**
The dynamic RCS of m_{engine}, N_{obs} = 1 and β = 0°.

**Figure 15.**
The dynamic RCS of m_{engine}, N_{obs} = 1 and β = 0°.

**Figure 16.**
Surface electromagnetic scattering characteristics of m_{engine}, α = 20° and β = 0°; RCS unit: dBm^{2}.

**Figure 16.**
Surface electromagnetic scattering characteristics of m_{engine}, α = 20° and β = 0°; RCS unit: dBm^{2}.

**Table 1.**
Main geometric characteristics of the turbofan engine.

**Table 1.**
Main geometric characteristics of the turbofan engine.

Model | m_{fan} | m_{comp} | m_{high} | m_{low} | m_{duct} |
---|

Airfoil | AG 08 | AG 25 | AH 21 | ARA-D 10% | — |

Outer radius/m | 1.485 | 0.630 | 0.563 | 0.806 | 1.946 |

Number of blades | 12 | 10 | 18 | 16 | — |

**Table 2.**
Motion parameters of the rotors of the turbofan engine.

**Table 2.**
Motion parameters of the rotors of the turbofan engine.

Model | m_{fan} | m_{comp} | m_{high} | m_{low} |
---|

Rotating speed/r/min | 8000 | 10,000 | 10,000 | 8000 |

**Table 3.**
Grid size for each part of the turbofan engine.

**Table 3.**
Grid size for each part of the turbofan engine.

Area | Maximum Value/mm | Area | Maximum Value/mm |
---|

Global minimum size | 2 | Fan blade trailing edge | 5 |

Fan blade leading edge | 8 | Fan blade | 25 |

Fan hub | 35 | Blade trailing edge of m_{comp} | 4 |

Blade leading edge of m_{comp} | 10 | Blade of m_{comp} | 25 |

Hub of m_{comp} | 25 | Blade trailing edge of m_{high} | 5 |

Blade leading edge of m_{high} | 10 | Blade of m_{high} | 25 |

Hub of m_{high} | 25 | Blade trailing edge of m_{low} | 6 |

Blade leading edge of m_{low} | 10 | Blade of m_{low} | 25 |

Hub of m_{low} | 30 | Support | 50 |

Inner duct | 120 | Outer duct | 150 |

**Table 4.**
Influence of azimuth on radar cross-section (RCS) mean of m_{fan}, N_{obs,fan} = 1, β = 0°.

**Table 4.**
Influence of azimuth on radar cross-section (RCS) mean of m_{fan}, N_{obs,fan} = 1, β = 0°.

α/° | −10 | 0 | 10 | 20 | 30 |
---|

RCS mean/dBm^{2} | 23.181 | 1.709 | −0.039 | −0.934 | 1.427 |

α/° | 40 | 50 | 60 | 70 | 80 |

RCS mean/dBm^{2} | 3.883 | 9.056 | 16.284 | 9.748 | 2.518 |

**Table 5.**
Influence of elevation angle on RCS mean of m_{low}, N_{obs,low} = 1, RCS unit: dBm^{2}.

**Table 5.**
Influence of elevation angle on RCS mean of m_{low}, N_{obs,low} = 1, RCS unit: dBm^{2}.

α/° | 150 | 160 | 200 | 210 |
---|

β = 0° | −6.316 | −10.437 | −10.862 | −6.649 |

β = 10° | −5.450 | −13.122 | −12.813 | −5.474 |

β = 20° | −0.460 | −12.180 | −11.966 | −0.496 |