We present the results of an analysis of flows in a gap between the reentry vehicle of a manned spacecraft and the propulsion bay located behind it in the case of their separation due to an emergency situation of the rocket in the active region of its trajectory. Emphasis is placed on different-in-nature oscillation processes occurring in transonic flight regimes. An approach to the estimation of the regimes of self-oscillation existence and their frequencies is proposed on the basis of the problem geometry and the flow conditions.

This paper presents a method for reconstructing the gas-dynamic parameters of gas flow based on non-contact PIV measurements of the velocity field. The wake flow past a model single rocket nozzle of an emergency escape system in the normal transonic (Mach number is 0.85) flight regime of the manned spacecraft rocket is considered. The flow around the nozzle is numerically simulated using the RANS and LES methods. The results obtained by the proposed reconstruction method are compared with numerical and experimental data.

Представлены результаты анализа исследований течения в зазоре между возвращаемым аппаратом пилотируемого космического корабля и расположенным за ним двигательным отсеком при их разделении в случае аварии ракеты на активном участке траектории. Особое внимание уделено автоколебательным процессам различной природы, возникающим при определенных расстояниях разделения на трансзвуковых режимах полета. Предложен подход к оценке режимов существования и частот автоколебаний на основе геометрии задачи и условий обтекания.

The results of the numerical modeling of the impact of the wakes of the nozzles of an emergency rescue rocket unit (ERRU) on the surface of a manned spacecraft are presented. The calculations are performed in the context of the two-stage zonal RANS-LES methodology proposed and validated by the authors earlier. In this methodology, the wall-modeled LES (WMLES) is based on the well-known eddy-resolving approach IDDES. In this paper, this technique is improved by including in the WMLES-subdomain the first row of the ERRU’s nozzles and performing calculations in the entire (360°) azimuthal domain. This makes it possible to increase the accuracy of the calculations due to a more correct description of the wakes of these nozzles and to analyze the flow around the spacecraft at nonzero angles of attack. The effect of the flight’s Mach number on the amplitude-frequency characteristics of the pressure fluctuations on the surface of the spacecraft, including their alteration at the sonic barrier, is analyzed. In addition, at the transonic Mach number value of M∞ = 0.95, the effects of the angle of attack and the mutual azimuthal position of the nozzles of the first and second rows are studied.

A two-stage RANS-DDES model and the results of calculations of the turbulent trans- and supersonic flow around a manned spacecraft (MSC) in the course of the emergency separation of the reentry module (RM) after actuation of the propulsion device (PD) of the crew’s emergency rescue system (ERS) in the initial flight stage are presented. The study is focused on determining the unsteady aerodynamic and acoustic loads on the screen of the RM and the fairing of the engine compartment (EC). It is shown that the maximum level of the unsteady loads is reached on the fairing of the EC in the region of impingement of the turbulent structures of the shear layer separated from the command module. In addition, it is found that at the transonic flight in the initial stage of the detachment process, self-exciting oscillations are observed in the gap between the RM and the EC.

Detailed data on the measurement of the gas-dynamic parameters of the flow in the jet field at a large value of the relative total pressure (Npr = 70) are presented. A significant increase in the measured total pressure in the first cell of a supersonic weakly underexpanded jet has been experimentally revealed. An explanation is given of this effect associated with the mixing process in the region behind the Mach disk of the peripheral high-pressure flow and the axial flow behind the Mach disk. This explanation based on the data of the numerical calculation of the flow. Experimental data can be used to verify the results of numerical calculations.

The paper presents the results of an experimental investigation of the mixing layer parameters in the initial regions of transonic jets issuing from convergent nozzles with different internal roughness at the same Mach number in the jet core. It is shown that the mixing layer characteristics, namely, the radial profiles of the measured total pressure and the r.m.s. total pressure fluctuations, are self-similar in nature at distances greater than 1.5 of the nozzle exit diameter from the exit. The possibility of applicating nozzles with an increased degree of the internal surface roughness in investigating high-velocity jet flows is shown.

The paper presents the investigation results of the flow structure of cold supersonic jets flowing out of model nozzles with a Mach number on the exit Ma = 3.5: an axisymmetric nozzle, a nozzle with a rectangular critical section, a beveled nozzle with a rectangular critical section. Flow schlieren images and transverse measured total pressure profiles in the flow are presented. The influence of the critical section shape and the beveled exit section on the shock-wave structure of the flow is described.

Currently, various countries are working to create a prospective manned reentry space vehicle of a new generation. The development of a new manned reentry space vehicle is conditioned by the necessity to increase the number of crew members, increase the carrying capacity, and improve the accuracy of landing at a given point on the earth's surface. The listed requirements for the appearance of the prospective reentry space ship and the increase in its dimensions lead to an increase in its cost, which entails the expediency of its reusability. This imposes additional conditions on the design of the spacecraft. The braking of the reentry vehicle is carried out by aerodynamic braking in the atmosphere upper layers, the parachutes usage and the use of a multi-jet braking system near the landing surface. With this braking method, the task is to effectively control the braking jet propulsion system at landing regimes [1].

Experimental studies of two umdcmno's objects model at distances of their separation in a range from 0.5 to 5.0 of a midsection diameter of a forward object were made in TsNIIMash wind tunnel U-3M at under- and super- sonic speeds. Results of fluctuating pressure measurements on interfacing surfaces of this object are presented.