Vibration inducing and airflow guiding coupled tomato pollination method research based on gas–solid two-phase flow model

Abstract

Supplementary pollination helps to improve yield and quality for tomato planting in greenhouse. Current tomato supplementary pollination methods with vibrator or blower can only realize the vibration induced pollen release without particles guiding. The vibration pollen release inducing and airflow pollen movement guiding coupled tomato pollination method and numeric simulation model were imposed in this paper. Firstly, the numeric simulation model based on gas–solid two-phase flow model of tomato pollination under vibration inducing and airflow guiding was established which considering the shape and surface characteristics of tomato pollen particles. Then, the response surface test of three factors and three levels was conducted using the numerical model by taking airflow angle, airflow start time and airflow velocity as factors, the effective pollination amount as pollination effect evaluation indicators. The test result showed that the maximum effective pollinated pollen particles could be acquired with airflow angle of 12.67°, airflow start time of 519.45 ms and airflow velocity of 0.72 m·s−1. Finally, the movement characteristics of tomato pollen particles in the simulation model were compared with the actual high-speed photography observation. The pollen particles movement trajectories in the simulation model were similar to them in actual observation. And the average movement velocities of the pollen particles moving downward and upward were only 7.59 % and 8.33 % differences between the results in simulation model and in actual observation. The average coverage rate of pollen particles on the stigma was 9.59 % with the vibration inducing and airflow guiding coupled pollination method, which was 85.85 % and 100.63 % relatively higher than vibration pollination and airflow pollination. The results show that vibration inducing and airflow guiding coupled pollination method with the optimized airflow parameters can improve the pollination effect, and the numerical simulation model established in this paper were reliable. The research results in this paper lays a foundation for the design and optimization of tomato pollination method and provides a theoretical basis for the application of gas–solid two-phase flow model in the design of supplementary pollination equipment.