对抽油杆柱振动特性的新认识

New Understanding of Rod String Vibration Properties

建立了新的研究抽油杆柱纵向振动特性的力学模型，研究了抽油杆柱自由振动的固有频率以及抽油杆柱对各种激励的稳态响应。建立了单级杆柱第ｉ阶固有频率ｐｉ和基频ｐ０之间的关系，即ｐｉ＝（２ｉ－１）ｐ０，指出了单级抽油杆柱产生共振的条件是激励频率等于基频的奇数倍，证明了“ＡＰＩＲＰ１１Ｌ有杆抽油系统的设计计算推荐方法”中关于激励频率等于偶数倍基频时单级抽油杆柱将产生共振的结论是错误的，并指出了导致这一错误结论的根本原因是采用的力学模型是错误的。

A new mechanical model used to study the longitudial vibration property of the rod string is set up,and the natural frequency and the steady responses to exciting forces are studied.The relation of the first stage natural frequency with the basic frequency is set up,that is, p i=(2i-1)p 0 . The resonance condition of the single stage rod string is that the exciting frequency is equal to odd times of the basic frequency.The vibration properties of the rod string were also studied in API RP IIL,and the resonance condition of the single stage rod string is that the exciting frequency is equal to the even times of the basic frequency.It is demonstrated by theoretically analyzing and deducing that the conclusion of API PR IIL is wrong, the wrong conclusion is made because the mechanical model used by API is wrong.