Annotation: The semi-empirical technique of evaluation of external acoustic loads during lift-off is a modification of the known NASA SP-8072 technique based on empirically determined universal dependencies of jet section acoustic power on normalized coordinate and frequency (Strouhal number). The proposed technique was updated in respect of evaluation of mechano-acoustic effectiveness of supersonic jet, determination of spatial scale of sound generating zone in jet, and formation of sound radiation direction towards rocket’s head module. A detailed presentation of the sequence of solving the task set is provided. A comparative analysis of the NASA SP-8072 technique and the proposed modification is made.

Annotation: The paper considers the main aspects of acoustic loads measuring during the rocket launch as well as problem of staff, equipment and environment protection from destructive effect of noise, generated by rocket’s engine. Proposed is the procedure of acoustic loads measurement and calculation of the minimal acoustic noise-safe launching rocket distance, at which it is safe to put equipment and operating personnel. This procedure is based on sharing of the numerical simulation of the exhaust jet in the ANSYS software system, engineering approaches in calculation of propagation and extinction of acoustic waves and measurement of the actual values of acoustic loads with the use of several noise meters. Effective sanitary standards of noise safety were taken to define the duration and power of acoustic loads safe for the personnel. As an example of use of this procedure, results of calculation of noise levels, provided by the sound attenuating chamber, and measurement data during the pulsed wind tunnel tests have been presented. As an outcome of calculations and measurements, done by the proposed procedure, outlines of the noise-safe zone were successfully defined and number of modifications suggested for the sound attenuating chamber to reduce the acoustic loads it generates.

Annotation: The article considers the procedure for evaluation of acoustic stressing parameters at the observation point nearby the launch vehicle nose cone when passing the sectors with maximum velocity heads and close to 1 Mach numbers. And the problem is set to determine the overall sound pressure level and the corresponding levels in octave and 1/3-octave frequency bands. Procedure under consideration is based on the semi-empirical dependency of characteristics of the wideband aerodynamic noise, which occurs during the launch vehicle flight at high velocities due to the turbulent pressure fluctuations and dimensionless aerodynamic parameters of the main stream. General idea of this approach is to establish relation of the velocity heads with wall pressure fluctuations in the boundary layer, calculating shear stress (friction) on the shell surface based on relationships applicable in the boundary layer theory and engineering experience. Attempts of development of similar calculation models go back to the early efforts, dedicated to the study of the aeroacoustics of the launch vehicle in flight. Main advantages of the procedure are its simplicity and versatility since it can be used to determine the acoustic loads around the payload fairings of launch vehicles of different sizes and shapes within the wide range of flight velocities and altitudes.