Numerical analysis of poise resulting in the low-frequency vibration of the engines

Abstract

Introduction. When designing engines, there comes the neccessity to evaluate their low-frequency vibrations caused by the imbalance, as well as the effectiveness of measures aimed at their (vibrations) reduction. In this case the criteria of engine equilibrium can be applied. The review of all known equilibrium criteria was made, the requirements for a rational criterion were formulated (physical meaning, dimensionless representation, universality, possibility to take into account all possible sources of imbalance, etc.).

The purpose of the study was to substantiate the criterion of equilibrium, which took into account the disturbing forces of inertia and the moments of all the orders, including those caused by the operation of attachments.

Methodology and research methods. The calculation of the proposed criterion to study the dynamics of mechanical and mechatronic systems was carried out using CAD / CAE technology including three-dimensional modeling and subsequent simulation of the motion of the engine model in the environment of software products.

Scientific novelty and results. The rms value of the vibration displacement of the engine mounts, referred to the radius of the crank (or the rms value of the vibration velocity of the support, referred to the average piston velocity) has been proposed to use as a criterion for balance. The harmonic components of the disturbing forces of all orders, including those due to the operation of mounted units, the presence of balancing mechanisms, etc. were taken into account at that.

The practical significance lies in the possibility to compare and assess of the low-frequency vibration caused by both imbalance and gas forces, as well as in the effective measures aimed at its reduction.