Suchergebnisse

The problem of calculating the equatorial damping moment during trajectory flight is an actual problem inballistic studies of the rotational motion of artillery projectiles. The practice of ballistic research needs short algorithmsthat make it possible to calculate the damping moment together with the calculations of the trajectory parametersunder conditions of continuously changing characteristics of the oncoming flow. In this regard, a simplified methodfor calculating the equatorial damping moment of artillery projectiles in the oncoming flow is proposed, based onthe differentiation of the dependence for the overturning aerodynamic moment by the angle of attack and the Machnumber of the oncoming flow. Calculations of the parameters of the rotational motion of the 155-mm artilleryprojectile on the flight trajectory have been carried out. The influence of the equatorial damping moment on theperiodic components of the angular displacements of the projectile is revealed. The results of ballistic calculationswith the loss of stability of the rotational motion of the projectile showed the destabilizing effect of the equatorialdamping moment on the boundary parameters in terms of stability in the case of opposite directions of rotation ofthe projectile and crosswind.

The use of modern computer systems for calculating the aerophysical characteristics of supersonic bodies of revolution together with the calculation of the flight trajectory under conditions of continuously changing Mach and Reynolds numbers of the oncoming flow, the presence of transient regimes and non-isothermality in near-wall flows is often not possible due to the complexity of the organisation of the computational process. By using a number of integral methods for calculating inviscid flows and viscous compressible near-wall flows, taking into account the non isothermality and intermittency of the boundary layer, a method has been developed for calculating the friction and heating of supersonic bodies of revolution on the flight trajectory. On the basis of well-known flight experiments, the correlation dependences of the Reynolds numbers of the beginning of the transition on sharp cones were obtained and the method of corrections for spherical blunting of the head part was implemented. By calculating the intermittency function, the changeability of flow regimes in the boundary layer is established for a number of trajectories of the supersonic uncontrolled rocket projectile. Calculated dependences for aerodynamic friction, heat fluxes and projectile wall temperature on the flight time are obtained. The concept of combined calculation of aerophysical characteristics on the flight trajectory using numerical and integral methods is proposed.