Hybrid Empirical/Computational Aeroacoustics Methodology for Rocket Noise Modeling

Integrated Aero–Vibroacoustics: The Design Verification Process of Vega-C Launcher

“…In particular, the first Eldred model [8] is based on the observation that each slice of the jet contributes to acoustic radiation, mostly in the frequency band f i that depends on the distance of the slice from the exhaust. The subsequent reformulation of the approach states that each slice contributes to the full noise spectral frequency content with an overall power that depends on its curvilinear distance from the exhaust [12]. Differently from the original Eldred model, which directly provides a definition of the sound pressure level (SPL), its reformulation can be revised to provide an explicit formulation of the acoustic pressure phasor p j [14].…”

“…The second formulation of the Eldred model assumes a contribution from each jet slice to the full noise spectral frequency content with an overall power that depends on its curvilinear distance from the exhaust [12]. Denoting w(s k ) as the sound power per unit axial length, the contribution of each slide reads as…”

“…In this simple model, in order to determine a realistic equivalent noise source, several parameters, such as the vehicle geometry or launch pad configurations, have to be taken into account. Several hybrid methods have been proposed for overcoming this limit [12,13], and the new formulation contains an explicit expression for the acoustic pressure of each noise source, in terms of amplitude and phase, in order to account for correlation effects and propagate the signal using a wave equation. The noise prediction obtained with the revised Eldred-based model has thus been used for formulating an empirical/BEM approach that allows us to evaluate the scattering effects, which, summed with the direct, correlated acoustical pressure, is exploited for the prediction of the aeroacoustics loads of the VEGA launch vehicle at lift-off.…”

Study on Acoustic Prediction and Reduction of Epsilon Launch Vehicle at Liftoff

“…The result taken in the static-firing test of the 260-kN solid motor is scaled to a radius of 60De with Eq. (10). A comparison of the OASPL distribution is shown in Fig.…”

Empirical Prediction of Acoustic Load of Launch Vehicle Including Jet Impingement

“…Sutherland [4] 는 방사되는 전체 음향파워에 대한 새 로운 예측식을 제안하였고, Casalino [5] 는 구조물에 대한 반사, 확산, 회절 효과 등을 고려하기 위해 혼합 적 예측모델을 제안하였으며 Plotkin [6] 은 얇은 판 모 델을 활용하여 음향하중 감소효과를 고려하였다. 그 중 Varnier [7] 와 Heynes [8] Fig.…”