Parameters optimization and application scope of eccentric hubs as means for permissible friction torque enhancing of liquid rocket engines articulated steering units

Аuthors

Balyakin V. B.^*, Lavrin A. V., Dolgikh D. E.^**

Samara National Research University named after Academician S.P. Korolev, 34, Moskovskoye shosse, Samara, 443086, Russia

*e-mail: 029-029@mail.ru
**e-mail: i@dolgih-work.ru

Abstract

The authors considered a notional sum of the friction moment and a moment from the asymmetry in the articulated steering unit under condition of the upper limit of the said aggregate moment. For the first time in the practice of studying steering units torque characteristics of liquid rocket engines (LRE), an aggregate torque parameter was introduced, characterizing the above mentioned conditional sum. The obtained parameter components may be herewith independent variables. The previously declared method of this conditional value adjusting by eccentric hubs may be supplemented by an additional parameter optimizing, i.e. the hubs eccentricity and compensating moment directly associated with it. The currently available analytical dependencies define concretely only the boundary of commencing application of hubs as adjusting elements. The numerical boundary value herewith is unambiguously defined as a half of the compensating torque, created by the eccentric hub, value. In the furtherance of the subject, the value itself of the compensating torque was considered in detail. The dependence of the said adjustable value in the form of the simplest function, which argument is the entire permissible range of the torque, on the thrust asymmetry of the steering unit was established based on the graphical solution. Joint determination of regulation commencing and the adjustable value allows elaborating a universal technique for the aggregate torque correction applicable for the articulated steering units under any limitations for the torques composing the sum. This technique may be applied herewith both at the design stage and in the process of the existing structures modification while operational conditions changing. The newly obtained analytical dependencies allow determining the margin of the friction torque increase without increasing its upper set limit.

Implementation of the new technique for torque characteristics adjustment allows reducing the process of serial structures fine-tuning to the required friction torque values by simple increasing of the admissible value. The said possibility contributes to the number of costly repeated tests number reduction.

Keywords:

steering unit, thrust asymmetry, corrected torque, eccentric bushing, optimal eccentricity

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