Vortices generated in a solid rocket motor may cause pressure oscillations, which cause problems such as deteriorated flight performance and payload damage. The building-cube method (BCM) solver is expected to accurately predict such vortex flows using high-order schemes as well as easily manage complex configurations. The aim of this study is to establish an analysis method for the internal flow of a solid rocket motor using the BCM. Computational results obtained in this study are compared with analysis data based on other solvers as well as experimental data for validation. The BCM solver is applied to the validate the converging-diverging verification nozzle, upper jet model, and propellant surface ejection model. Furthermore, it effectively captures the three-dimensional (3D) trailing vortex downstream of the inhibitor and the propellant surface injection flow. In general, the 3D BCM solver accurately reproduces the internal flow field of the solid rocket motor.
The benefit of Boundary Layer Ingestion (BLI) was evaluated by wind tunnel test and analysis. Using a simple engine/airframe model which is composed of an airfoil based on NACA0012, an electric fan and an electric motor, wind tunnel test was conducted. Net streamwise force and electric power were mainly measured. Based on the power balance method originally described by Drela, the concept of conversion efficiency was added to separate demerit of BLI. By using conversion efficiency, mechanical power was changed to electrical power and making it easy to understand benefit of BLI. This analytical method was fit with experimental data and well represent BLI benefit. At cruise condition in 40m/s, BLI configuration needs lower 7.66% electrical power than nonBLI configuration.
The characteristics of active-grid-generated flows are investigated. The streamwise flow velocities are measured using a hot-wire anemometry. The turbulence intensity, integral length scale, and power spectrum density are evaluated to understand the influence of active-grid-operating parameters such as the rotation rate of the grid's agitators and the duration of the agitator's constant-rate rotation. The effects of randomized rotation and the test-section type are also investigated. It is found that the randomization of the rotation rate improves the spectrum distribution of velocity fluctuation, while the statistical quantities of turbulence are not sensitive to the randomized rotation rate. The randomized duration does not affect the generated flow characteristics. The turbulence intensity and integral length scale can be correlated with a non-dimensional parameter expressed by the rotation rate, mesh size, and free-stream velocity. When the non-dimensional parameter is small, the test-section type shows no influence on the turbulence intensity and integral length scale.