Influence of different geometric structures on thermal protection characteristics of fuel nozzle

The deposition performance of tubes with different structures was studied experimentally, And the results showed that when the inflow temperature, inflow velocity, fuel inlet temperature and velocity was 1 000 K, 150 m/s, 400 K and 05 m/s, the test pieces with smaller angles and expansion sizes had less deposition on the tube wall, and the amount of deposition fluctuated with the increase of time during the initial stage of heating. The amount of deposition on the tube wall reached the maximum when heating for 15 minutes, and then the removal of a part of deposition caused the reduction of deposition measured. The influence of fuel nozzle and nozzle cap with different geometric structures on thermal protection characteristics was studied by means of numerical simulation and experiment. Results showed that the fuel nozzle with concentric arrangement of primary and secondary fuel passages had the best thermal protection effect, which could reduce the maximum wetted wall temperature by nearly 50% under test conditions, even better than the model with air gap. Reducing the contact area between the nozzle cap and the nozzle body or filling the materials with low thermal conductivity were effective improvement measures, which could reduce the outlet oil temperature by about 5 K. The results of this study have guiding significance for the design of fuel nozzle thermal protection.