Flow Field Analysis And Application Of Greenhouse Tomato Assimilation Products Based On CFD

The greenhouse tomato assimilation product allocation sub-model is the core component of the greenhouse tomato growth simulation model,and is also an effective method to strengthen the greenhouse tomato cultivation management and optimize the greenhouse environment regulation.At present,the distribution mechanism of assimilation products to different organs is not clear,and the tomato assimilation product distribution model has always been a weak link and a research hotspot of tomato growth models.Studies on plant physiology have shown that the assimilation products produced by the tomato source organs in the greenhouse are transported to the reservoir organs in the form of sucrose when passing through the sieve tube of the stem phloem.Situation,analysis of the distribution dynamics and migration law of assimilation products in tomato stalks has an important role in clarifying the distribution mechanism of tomato assimilation products in greenhouses.This paper takes greenhouse tomato plants in each growth cycle under different nutrient solution concentrations as the research object.First,the CFD method is used to simulate the distribution of sucrose flow field in tomato stems under the same treatment,and the chemical test is used to verify the CFD The scientific validity of the assimilation product flow field analysis method;secondly,the tomato plants under different treatments are analyzed to obtain the spatial and temporal distribution of assimilation products in the greenhouse tomato stalk;finally,by developing a suitable for greenhouse tomato production management A special small-scale leaf removal device improves the distribution efficiency of assimilation products in tomato stalks.Specific research contents are as follows:(1)Using CFD method to simulate calculation and verify analysis of sucrose flow field in greenhouse tomato stalkCombining the CFD method with the physiological characteristics of tomatoes,the sucrose flow field in the greenhouse tomato stalks in each growth cycle(seedling stage,flowering and fruiting stage,picking period)under normal nutrient solution concentration was simulated,using spectrophotometry The CFD simulation results were compared and verified by the method.The results showed that: from the perspective of spatial distribution,at the seedling stage,the content of assimilation products at both ends of the tomato stem was slightly higher than the middle part,andthe flow velocity at both ends of the stem was higher than the flow velocity and pressure The distribution is opposite,and the values are relatively low;during the flowering and fruiting period,the content of assimilation products in the middle and lower parts of the stem is the lowest,followed by the root region,and the contents of the top and middle and upper parts of the stem are higher,and the flow velocity of the top and middle and upper parts of the stem It is also higher than other parts,the pressure distribution is opposite,and the values are greatly improved;during the picking period,the content of assimilation products in the middle and lower parts of the stalk is the lowest,the growth points of the root and the top are followed,the content in the middle and upper part is the highest,and the stalk The flow velocity in the upper part is generally higher than other parts,the pressure distribution is opposite,and the value reaches the highest value in the entire growth period.From the perspective of time change,in each growth cycle,the content of assimilation products in the stalks generally showed a trend of first increasing and then decreasing,and the highest value appeared in the time range from 10:00 am to 12:00 noon.(2)Studying the effect of different nutrient solution concentrations on the distribution rule of assimilation products in tomato stalks in greenhouseFor greenhouse tomato plants treated with different nutrient solution concentrations(ie,50% normal concentration,100% normal concentration,and 150%normal concentration),the above CFD method and chemical method were used to analyze each group of data,and the greenhouse was finally obtained.The distribution dynamics and migration law of tomato assimilation products in the transport tissue of the stalks,the results show that: within a certain range,the higher the concentration of nutrient solution,the more adequate the supply of nutrients,the larger the area of the assimilation products in the high-pressure area of the stalks,The higher the average pressure value,the more obvious the change in flow rate.With the growth and development of tomato plants,the content and transport rate of assimilation products in the leaves at the lower part of the stem gradually decreased.This will not only affect the growth and development of tomatoes,but also increase the probability of being infected with diseases and insect pests.Therefore,in the later stages of flowering and picking of tomatoes,the old leaves at the bottom of the tomato plant need to be trimmed and removed to improve the assimilation products in the tomato stem Distribution efficiency.(3)Design and develop a special small-scale leaf removal device suitable for greenhouse tomato production managementIn response to the above-mentioned greenhouse tomato leaf removal problem,a special small-scale leaf removal device suitable for greenhouse tomato plants was designed and developed.The device is composed of several parts such as pruning system,lifting system and control system.Using the GX80 double-track precision ball screw linear slide module as a vertical lifting mechanism,the ring cutting device developed and designed can protect the tomato plant stems.Damaged,at the same time,it can meet the requirements for cutting the leaves,and through experiments to verify the performance of the device and the rationality of the structural design,it can complete the predetermined goals of the design,thereby strengthening the plant type management of the greenhouse tomato and improving the machinery during the tomato production Adaptability.