The relationship among the axial thrust force,pressure of pipeline wall,load capacity of fluid and circumferential drag torque of inner and outer spiral robots,single sectional outer spiral robots and double sectional outer spiral robots and their outer shell rotational speed was numerically compared.The influence of the
inner spiral rotational speed and the outer spiral rotational speed on the robotic motion performance was calculated.The influence of the outer spiral structural parameters(notch width a2,groove bottom width b2,dip angle α2,groove depth h2,spiral angle Φ2 and thread number n2) of the robot on the robotic axial thrust force was numerically analyzed.By the orthogonal optimization design method,an optimal combination of the six outer spiral structural parameters was obtained.The results show that the effective axial thrust force and load capacity of fluid of the inner and outer spiral robot are maximal;the influence of the outer spiral parameters on the robotic motion performance is much larger than that of the inner spiral parameters;outer spiral structural parameters have nonlinear relation with the robotic axial thrust force;under the condition of the fixed pipeline diameter and robotic inside and outside diameters,an optimal combination of the six outer spiral structural parameters is that a2 equals to 1.25mm,and b2 equals to 0.75mm,and α2 equals to 70°,and h2 equals to 0.8mm,and Φ2 equals to 30°,and n2 equals to 10.
