A multi-channel Tunable Diode Laser Absorption Spectroscopy (TDLAS) system was designed and constructed for flow parameters diagnostics in a scramjet combustor. Two fiber coupled distributed feedback (DFB) lasers with narrow line width were used to probe two H 2 O absorption features (7185.597cm (combined)) by using direct absorption Time-Division-Multiplexing (TDM) strategy at a 4-kHz repetition rate. Laser light was split into five beams and transmitted across the test region. Two motorized precision translation stages were used to move the collimators during the test, so that the three beams located near the cavity and at the exit of the combustor can scan the cross sections respectively. Flow parameters could be obtained simultaneous which included average temperature, water vapor concentration and velocity at the entrance of the combustor, the distribution of temperature, water vapor concentration at a cross section near the cavity, the distribution of temperature, water vapor concentration and velocity at the exit cross section of the combustor. The parameters of the flow entering and exiting the combustor could be used to evaluate the performance of the direct-connected scramjet facility and the combustion efficiency of the combustor. The parameters at the cross section in the combustor could also be used to analysis combustion characteristics in the combustor.

The TDLAS and static pressure were used to investigate the combustion of the excited ethylene jet into the supersonic flow in this article. The jet was from the Hartmann-Sprenger tube, which was put into the traditional jet device. The jet was excited at three different frequencies and compared with the base case without excitation. The results showed that the higher static pressure could be obtained in the excited cases. The excited jet didn't only take effects on the jet shear layer, but also influenced the turbulence intensity near field, and the right excited frequency can short the mixing and combusting distance. The excited jet can help reduce the combustor length. Nomenclature

To better evaluate the performance of dual-mode scramjet combustor, the axis distribution of heat release must be predicted accurately. Current work is based on a modified 1-D model assisted by measurements acquired in a dual-mode combustor on directconnected scramjet facility. CH

In this paper, a numerical analysis coupling heat transfers of the combustor internal flow, the coolant flow and the strut wall is developed and applied for the optimization of strut cooling using aviation kerosene as coolant at flow conditions corresponding to the combustor entrance condition for Mach 6 scramjet flight. The coupling procedure is tested and proven to be an efficient method of being capable to obtain the converged temperature and heat transfer solutions of the cooled strut within a few iteration steps. Four cooling designs with varied diameter, length and position of the cooling channels are investigated and their improvements on fuel injection and mixing are also verified compared to the wall injection. The kerosene-cooled strut (Strut4) is tested in a Mach 2.5 supersonic tunnel with inlet total temperature and total pressure of 1900K and 1.45MPa respectively for 60 seconds. The damaged part in the upper leading edge of the strut is observed, which is consistent with the result obtained by the numerical analysis.

Abstract:The three-dimensional compression scramjet inlet has been investigated by using surface oil dot visualization and numerical simulation. The research has revealed the details of the internal flow pattern, which included the structure of the shock waves, the spillage, the spatial vortical structures, and the boundary layer separations etc.. These features determined the performance of the inlet, which gave the mass flow capture ratio of 0.86, total pressure recovery of 0.41. The results showed that the arrangement of the shocks is critical for such kind of inlet. More researches have been carried out to investigate the effect of the cowl shape, and the results showed the flow field would be changed little for the cowls with different shapes but the same internal contraction ratios.