@article{Nikolin_Sokol_Frolov_2021, title={ON THE INFLUENCE OF THE GAS DUCT SHAPE ON THE ACOUSTIC LOADS VALUE AT THE LIFT-OFF OF THE LAUNCH VEHICLE WITH A SINGLE NOZZLE}, volume={28}, url={https://rocketspace.dp.ua/index.php/rst/article/view/89}, DOI={10.15421/452018}, abstractNote={<p><strong>The gas-dynamic type of launch from open launch sites is mainly used during the launch vehicles launching. Its accompanied by the occurrence of huge gas-dynamic and acoustic loads that affect both the payload and ground structures in general. The implementation of gas ducts with gas reflectors with a special shape and dimensions is one of the ways to reduce these loads. The purpose of this work is implementation of the numerical method of simulation to demonstrate changing acoustic loads when the geometric parameters of the gas duct change. The simulation of the gas-dynamic launch of the launch vehicle from the launch pad, where the spent jets are discharged with the help of a gas duct, has been conducted (Fig. 1, 2). The calculations were performed for the case when the distance between the nozzle exit and the gas inlet is 9400 mm. The Mach number at the nozzle exit is 3.95, and the temperature is about 1820 K. The nozzle pressure ratio is 0.48. In the current work, the depth of the gas duct (h) applies the values – 5500 mm, 6500 mm, 7500 mm, while the angle of inclination of the deflector (φ) is - 61.9<sup>о</sup>, 66.6<sup>о</sup> and 70<sup>о</sup>, respectively. In this paper, the simulation of gas-dynamic processes is carried out using non-stationary Reynolds-averaged Navier-Stokes equations using the k-ω SST turbulence model. Broadband noise models were used to assess acoustic loads.</strong></p> <p><strong>Based on the calculation results, the distributions of the Mach number, pressure, temperature, and the acoustic power level inside of the gas duct are constructed. It was found out that with increasing of the gas duct depth the acoustic power of the jet remains unchanged, but the acoustic power level of noise radiation in the environment decreases. Calculations have shown that the shallower the gas duct depth, the higher the acoustic power level. For example, at h = 7500mm the average acoustic power level in the environment is in the range of 90 ÷ 110dB, then at h = 5500mm it is already 110 ÷ 130dB.</strong></p>}, number={4}, journal={Journal of Rocket-Space Technology}, author={Nikolin, S. and Sokol, G. and Frolov, V.}, year={2021}, month={Oct.}, pages={129-142} }