A technique has been developed for thermal-vacuum strength tests of heat-shielding structural elements for temperatures up to 1400 K. Heating and vacuum equipment for these tests has been developed and the accuracy of measuring the temperature on the surface of the heat-shielding coating has been studied. Recommendations are given on the use of K-type thermocouples for these tests.
The possibility of occurrence of near-resonant rotation modes during uncontrolled descent of spent first-stage boosters of launch vehicles in the atmosphere due to small mass-inertial asymmetry is considered. The stability of near-resonant rotation modes is analyzed using a quasistatic approach.
Results of experimental investigation of steady aerodynamic characteristics and heat flux distribution over the surface of the DM-18 lander of the "ExoMars" project at hypersonic flow regimes are presented.
Results of comprehensive numerical and experimental investigations of isolated bypass nozzles with separate exhaustion of the flows in the first (gas generator) and second (fan) circuits of the turbofan engine with different bypass ratios are reported. Rational geometric parameters of the nozzles, which ensure the minimum thrust losses, are determined. The effects of the Mach number of the external flow, pressure ratio in the circuits, and presence of a pylon are investigated. The characteristics of bypass engine nozzles with separate exhaustion of the flows and with their mixing are compared with due allowance for friction, pressure drag, and internal thrust losses.
This paper describes experimental studies of nozzles in a distributed power plant with separate exhaust configurations of gases from the first and second circuits of a bypass turbojet engine. The nozzles are located in the trailing edge of the wing of a quiet aircraft and have a sonic exit section of a trapezoidal shape. Only the aerogasdynamic characteristics of the nozzles are considered. It is demonstrated that the thrust loss of trapezoidal nozzles is close to that of the well-known round and plane nozzles. The influence of the airframe elements (wing and fuselage) on the effective thrust loss is examined, and the conditions for minimum negative interference of the jet and the external flow with closely spaced airframe elements are determined. A comparative analysis of the integrated layout of trapezoidal nozzles located in the wing with the layout of typical round nozzles of a bypass turbojet engine above or under the wing allows us to conclude that it is possible to provide approximately the same level of effective thrust loss.
