Cavitation in the aircraft fuel systems can lead to unexpected damage to fuel-system components. Modeling fuel cavitation is challenging due, in part, to the fact that fuels are a complex mixture of hundreds of hydrocarbons. This study is focused on the fundamental understanding of cavitation inception, shock wave generation mechanisms, and bubble dynamics in aviation fuels via rigorous experimental studies and modeling efforts.
First, we present unprecedented quantitative data on shock wave propagation characteristics in the converging-diverging nozzle obtained via a novel high-speed image processing technique we term “enhanced gradient shadowgraphy”. Two sustained mechanisms are found to be responsible for shock wave generation. We obtain nonlinear solutions of the governing equations to predict shock speeds. Good agreement is achieved with experimental data.
Second, we employ advanced computer-vision algorithms to extract quantitative data from high-speed imaging on the bubble spatial-temporal evolution and breakup kinematics. We show that the initial bubble size plays an essential role in the resulting void fraction variation but not in the breakup kinematics. We also define a unique dimensionless parameter that predicts the bubble breakup event for different fuels and flow regimes.
Lastly, we derive a new model to predict cavitation collapse in radial flow between two parallel disks with a thin gap, representing a geometry relevant to aviation fuel pumps. The model predictions of the cavitation cloud collapse in the disk geometry show remarkable agreement with experimental data. Our findings shed light on the complex physics of fuel cavitation and the dynamics of nonspherical cavities.
