The general equations of motion of a flexible spinning missile under thrust in the powered flight phase are established and the stability of the motion of the missile is analyzed. The spinning missile is approximated to the unconstrained flexible rotor. Moreover, the thrust in the powered flight phase is deemed as a follower load when the factors of gyroscopic effect, aeroelastic effect, and axial force are considered under the mean axis condition. The equations of motion and stability of the flexible spinning missile in the powered flight phase are then deduced. The stability and dynamic response of the flexible spinning missile under thrust is analyzed through numerical calculation. Calculation results show that thrust, spinning speed, and dynamic pressure exert different influences on the stability of the spinning missile. These factors should be considered and analyzed comprehensively.

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Abstract. Increasing demands for more efficient screw compressors design method to overcome the problems of rotor profile modification and compressor performance test establishment. A new method for the design of screw compressor shape, size and dimension is described here. As a result, NURBS curves and computational fluid dynamics (CFD) theory being applied to overcome these two problems. NURBS curves are introduced to construct a new rotor profile based on the rotor profile of unilateral asymmetric combined cycloid with pin gear arc. The numerical simulation models of the new profile and the original profile are built to find out the distribution law of pressure and velocity in twin-screw compressors under the operating speed by the means of FLUENT software. Finally, according to the simulation results, the rationality of the designed rotor profile is verified, and new schemes for further optimization are explored.

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