Development Of Spectral And Wavelet Time-of-flight Methods For Propagating Shock And Detonation Waves

An accurate time delay estimate for a propagating disturbance, including an estimate of its uncertainty, is important in many areas of science. Several techniques were developed for determining the propagation time of a shock and detonation wave. The speed of the propagating wave was then determined by the time delay estimates provided for the best techniques. The techniques used ranged from the commonly used time-of-flight method to a nonstationary cross-spectral density phase method that provided a statistical estimation of the propagation time. The time delay results for a shock tube experiment showed that most of the methods had difficulties in determining a feasible time delay estimate. These methods tended to be more sensitive to a moving time window developed for nonstationary signals. The results also showed that the application of the envelope signals typically improved the propagation time estimates. The only methods that provided a reasonable time delay estimate on a consistent basis were the nonstationary envelope correlation coefficient method and two variations of the Haar wavelet methods. The time delay estimates from these methods were then used to provide a statistical estimate of the velocity of the propagating waves.