Control of a dual-mode scramjet flow path utilizing optical emission spectroscopy

Abstract

Shock train leading edge (STLE) location control within a Dual-Mode Scramjet (DMSJ) flow path was demonstrated using an optical emission spectroscopy (OES) sensor for control feedback. Emission from electronically excited chemical species, OH⁎ and C2⁎, was observed within the combustor and used for feedback to control the STLE within the DMSJ isolator. An optical emission sensor was used to experimentally demonstrate STLE control using a Proportional-Integral (PI) controller. Feedback using this sensor was compared the traditional approach of using wall pressure sensors. Utilizing an OES sensor for feedback proved to be an effective method to estimate and control the STLE location and provided a smoother response than when utilizing discrete wall-based pressure measurements that tended to discretize the estimated STLE location. Characteristic Model-Based All-Coefficient Adaptive Control (ACAC) was also implemented and compared to the PI controller response using the OES signal as feedback. Plant changes were introduced in the form of mass addition downstream of the combustor and a reduction of fuel valve response. Experiments showed that the ACAC and PI controllers behave similarly both during nominal operation and with plant changes, though the ACAC controller tended to command the fuel valve more efficiently. This paper presents the first experimental demonstration of closed-loop control of the STLE location within a scramjet flow path when using OES sensor feedback. This is also the first demonstration of adaptive control of STLE location utilizing OES sensor feedback.