Study of the resonant processes influence in the two-stroke carburetor engine intake tract on its speed characteristic Available to Purchase

Medium resonant oscillations in the intake tract of a two-stroke motorcycle engine were considered, and their influence on filling the crank chamber with combustible mixture, on its power and economic indicators, as well as on the speed characteristic shape is presented. It is shown that the intake noise main components are located in the range of low and medium frequencies; therefore, wave processes in the intake tract could be considered as the one-dimensional wave motion. Dependences are provided for determining the frequency of resonance oscillations in the intake tract based on the engine speed characteristic form. Expressions were obtained for calculating the crank case volume input impedance, as well as formulas for calculating the engine inlet window attached length. Dependences are proposed for determining the sound radiation impedance by the intake tract external opening exposed to the moving air flow, as well as for determining the loss of sound energy due to viscous friction, thermal conductivity and medium turbulence. Precise and simplified expressions are presented for calculating the modulus and the phase of the acoustic wave reflection coefficient from the intake tract outer opening. Dependences were obtained for calculating the intake channel intake impedance and the natural oscillations frequency in the intake tract based on its elements’ dimensions and the state of medium in them. As an example, calculation of the intake tract resonant frequency tract and its experimental verification were performed, which demonstrated satisfactory accuracy of the proposed calculation method. This study results in a possibility to calculate the intake tract design that provides the engine with the required form of speed characteristics.