Temperature Measurement Based on CARS in Scramjet Ignition Process

As a non-intrusive measurement method, coherent anti-Stokes Raman scattering (CARS) has been widely used in combustor temperature measurement and ground test of various engine models. However, the current works focus on the temperature measurement in combustion at steady-state, and lack the research about high-resolution measurement of the temperature and composition in combustion at transient-state. In this paper, a CARS spectrum calculating and fitting program CARSCF was developed. Its accuracy was verified by using McKenna combustor and comparing with the results from DLR. The result shows that CARSCF has sufficient repeatability and accuracy. The CARS signal in scramjet ignition process was measured and then used to calculate temperature. The results show that, during the H₂/air ignition at Mach 3, the CARS signal first rises rapidly and then falls sharply and finally rises slowly, while the temperature increases sharply and then decreases slowly with a maximum temperature of 1 511 K.