COMBINED CORRELATION TO PREDICT TRAJECTORIES OF AIRBLAST SPRAY AND JET IN CROSS-FLOWS-INDEPENDENT OF TWO-PHASE MOMENTUM RATIO

Most of the trajectory correlations of spray in cross-flow rely on two-phase momentum-ratio (q2). However, insufficient information about injector geometry might pose difficulty in calculation of q2, which may result in significant errors in the predictions. In this work, new empirical correlation is developed; the correlation is independent of q2 and can be used to predict windward trajectories of both, airblast spray and jet in cross-flow. Momentum of spray droplets is accounted by using physical properties of liquid and operating conditions, these parameters also control drop-sizes in airblast sprays. The validity of the correlation is established by comparing the predictions with current and past experimental measurements on different liquids including water and various hydrocarbon fuels; the predictions from past empirical correlations are also included in the analyses. The correlation shows good agreement with the experimental spray trajectories of water and fuel sprays in cross-flow with mean-absolute-percentage-error (MAPE) of 13.9%. The correlation is extended to predict trajectories of airblast sprays injected in evaporative cross-flows, this is achieved by introducing a temperature ratio term in the trajectory correlation. The predictions of temperature-dependent trajectory correlation agreed well with available experimental data on various fuels viz., ethanol, Jet-A and decane with maximum MAPE up to 15.89%. Further, the trajectory correlation of airblast sprays in cross-flow reduced to a power-law functional-form of trajectory-equation for classical jet-in-cross-flow configuration, which provides reasonable agreement (MAPE~14.58%) with the experimental data.