• Journal of the Korean Society of Propulsion Engineers
• /
• v.25 no.1
• /
• pp.42-49
• /
• 2021

As a measure of susceptibility on the combustion instability, thermo-acoustic instabilities in rocket combustion system was considered for the estimation of the operational stability margin. Growth rate, which governs the asymptotic stability behavior of the system, was determined from the dynamic data measured during combustion tests in order to understand the dynamic characteristics of combustor system. Frequency transform technique was first applied to determine the system parameters such as growth rate and/or damping coefficient for an interested mode from the time series pressure data, and the PDFs of pressure amplitude were extracted from the amplitude envelope of pressure oscillation for the stochastic analysis.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.25 no.12
• /
• pp.888-894
• /
• 2015

A new method for the simulation of the vehicle's interior road noise is proposed in the present study. The road noise model can synthesize road noise of a vehicle for varying driving speed within a range. In the proposed method, interior road noise is considered as a stochastic time-series, and is modeled by a nonstationary parametric model via two steps. First, each interior road noise signal, obtained from constant speed driving tests performed within a range of speed, is modeled as an autoregressive model whose parameters are estimated by using a standard method. Finally, the parameters obtained for different driving speeds are interpolated based on the varying driving speed to yield a time-varying autoregressive model. To model a full band road noise, audible frequency range is divided into an octave band using a wavelet filter bank, and the road noise in each octave band is modeled.