Nozzle Flow Model of High Pressure Variable-Rate Spraying Based on PWM Technology

2011 ◽  
Vol 422 ◽  
pp. 208-217 ◽  
Author(s):  
Chang Yuan Zhai ◽  
Xiu Wang ◽  
Da Yin Liu ◽  
Wei Ma ◽  
Yi Jin Mao
Keyword(s):  
High Pressure ◽  
Flow Model ◽  
Hypothesis Test ◽  
Test System ◽  
Nozzle Flow ◽  
Maximum Relative Error ◽  
Variable Rate ◽  
Flow Models ◽  
Pressure Variable ◽  
Variable Rate Spraying

Nozzle flow model for high pressure variable-rate spraying is indispensable when orchard sprayer is controlling liquid flow based on Pulse Width Modulation (PWM) technology. Three flow models for Teejet AITXA 8002, 8003 and 8004 nozzles are obtained by using nozzle flow model test system which is established in this paper. The results from equation hypothesis test and test for lack of fit of flow model shows that those three flow models work well. Nozzle flow model validation trials show that the relative errors of model flow and actual flow are small, while the maximum relative error is 6.50%; the flows characteristics of different nozzles with the same type are almost the same.

Injector nozzle flow model and its effects on the calculations of high pressure sprays

2004 ◽  
Vol 9 (4) ◽  
pp. 483-488
Author(s):  
Wei Ming-rui ◽  
Liu Yong-chang ◽  
Wen Hua ◽  
Zhang Yue-heng
Keyword(s):  
High Pressure ◽  
Flow Model ◽  
Nozzle Flow ◽  
Injector Nozzle

Mathematical modelling of salt purification by recrystallization. A cross-current flow model and its comparison with the countercurrent arrangement

1986 ◽  
Vol 51 (11) ◽  
pp. 2489-2501
Author(s):  
Benitto Mayrhofer ◽  
Jana Mayrhoferová ◽  
Lubomír Neužil ◽  
Jaroslav Nývlt
Keyword(s):  
Flow Model ◽  
Current Flow ◽  
Countercurrent Flow ◽  
Flow Models ◽  
Multi Stage ◽  
Stage Crystallization ◽  
The Cross ◽  
Current Flows ◽  
Set Up ◽  
Cross Current

A model is derived for a multi-stage crystallization with cross-current flows of the solution and the crystals being purified. The purity of the product is compared with that achieved in the countercurrent arrangement. A suitable function has been set up which allows the cross-current and countercurrent flow models to be compared and reduces substantially the labour of computation for the countercurrent arrangement. Using the recrystallization of KAl(SO4)2.12 H2O as an example, it is shown that, when the cross-current and countercurrent processes are operated at the same output, the countercurrent arrangement is more advantageous because its solvent consumption is lower.

Study of the Response of PW Traffic Flow Model to a Bottleneck on a Circular Road and its Suitability for Heterogeneous Traffic Conditions

2021 ◽  
Vol 9 (4) ◽  
pp. 460-463
Keyword(s):  
Fluid Flow ◽  
Traffic Flow ◽  
Flow Model ◽  
Equation Model ◽  
Heterogeneous Traffic ◽  
Flow Conditions ◽  
Flow Models ◽  
Traffic Conditions ◽  
Model Response ◽  
Traffic Flow Models

The traffic flow conditions in developing countries are predominantly heterogeneous. The early developed traffic flow models have been derived from fluid flow to capture the behavior of the traffic. The very first two-equation model derived from fluid flow is known as the Payne-Whitham or PW Model. Along with the traffic flow, this model also captures the traffic acceleration. However, the PW model adopts a constant driver behavior which cannot be ignored, especially in the situation of heterogeneous traffic.This research focuses on testing the PW model and its suitability for heterogeneous traffic conditions by observing the model response to a bottleneck on a circular road. The PW model is mathematically approximated using the Roe Decomposition and then the performance of the model is observed using simulations.

scholarly journals A system of conservative regridding for ice/atmosphere coupling in a GCM

2013 ◽  
Vol 6 (4) ◽  
pp. 6493-6568 ◽  
Author(s):  
R. Fischer ◽  
S. Nowicki ◽  
M. Kelley ◽  
G. A. Schmidt
Keyword(s):  
Finite Element ◽  
General Circulation ◽  
Flow Model ◽  
Source Code ◽  
Circulation Model ◽  
Surface Mass Balance ◽  
Ice Flow ◽  
Surface Mass ◽  
Flow Models ◽  
Ice Model

Abstract. The method of elevation classes has proven to be a useful way for a low-resolution general circulation model (GCM) to produce high-resolution downscaled surface mass balance fields, for use in one-way studies coupling GCMs and ice flow models. Past uses of elevation classes have been a cause of non-conservation of mass and energy, caused by inconsistency in regridding schemes chosen to regrid to the atmosphere vs. downscaling to the ice model. This causes problems for two-way coupling. A strategy that resolves this conservation issue has been designed and is presented here. The approach identifies three grids between which data must be regridded, and five transformations between those grids required by a typical coupled GCM–ice flow model. This paper shows how each of those transformations may be achieved in a consistent, conservative manner. These transformations are implemented in GLINT2, a library used to couple GCMs with ice models. Source code and documentation are available for download. Confounding real-world issues are discussed, including the use of projections for ice modeling, how to handle dynamically changing ice geometry, and modifications required for finite element ice models.

High-pressure variable temperature Raman studies on hexamethyl benzene crystals

1978 ◽  
Vol 7 (1) ◽  
pp. 49-53 ◽  
Author(s):  
J. S. Bodenheimer ◽  
W. F. Sherman ◽  
G. R. Wilkinson
Keyword(s):  
High Pressure ◽  
Variable Temperature ◽  
Pressure Variable

Second Order Slip Flow Effects on Heat Transfer Performance of Microchannels

2009 ◽  
Author(s):  
Cem Dolu ◽  
Lu¨tfullah Kuddusi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Flow Model ◽  
Slip Flow ◽  
Second Order ◽  
Flow Models ◽  
Uniform Wall Temperature ◽  
Uniform Wall ◽  
Slip Flow Regime ◽  
Flow Effects

First and second order slip flow models in rectangular microchannels heated at constant and uniform wall temperature are studied. The velocity and temperature profiles for hydrodynamically and thermally developed incompressible slip flow regime available in literature are used. The average nondimensional slip velocity and temperature jump are found by using first and second order slip flow models. The average Nusselt number is also derived by using both first and second order slip flow models. The effects of Knudsen number, aspect ratio and second order slip flow model on the heat transfer characteristics of microchannel are explored.

A quasi-one-dimensional model for an outwardly opening poppet-type direct gas injector for internal combustion engines

2019 ◽  
Vol 21 (8) ◽  
pp. 1493-1519
Author(s):  
Abhishek Y Deshmukh ◽  
Carsten Giefer ◽  
Dominik Goeb ◽  
Maziar Khosravi ◽  
David van Bebber ◽  
...  
Keyword(s):  
Natural Gas ◽  
Internal Combustion Engines ◽  
Flow Model ◽  
Direct Injection ◽  
Source Model ◽  
Gas Jet ◽  
Nozzle Flow ◽  
Combustion Engines ◽  
Compressed Natural Gas ◽  
One Dimensional

Direct injection of compressed natural gas in internal combustion engines is a promising technology to achieve high indicated thermal efficiency and, at the same time, reduce harmful exhaust gas emissions using relatively low-cost fuel. However, the design and analysis of direct injection–compressed natural gas systems are challenging due to small injector geometries and high-speed gas flows including shocks and discontinuities. The injector design typically involves either a multi-hole configuration with inwardly opening needle or an outwardly opening poppet-type valve with small geometries, which make accessing the near-nozzle-flow field difficult in experiments. Therefore, predictive simulations can be helpful in the design and development processes. Simulations of the gas injection process are, however, computationally very expensive, as gas passages of the order of micrometers combined with a high Mach number compressible gas flow result in very small simulation time steps of the order of nanoseconds, increasing the overall computational wall time. With substantial differences between in-nozzle and in-cylinder length and velocity scales, simultaneous simulation of both regions becomes computationally expensive. Therefore, in this work, a quasi-one-dimensional nozzle-flow model for an outwardly opening poppet-type injector is developed. The model is validated by comparison with high-fidelity large-eddy simulation results for different nozzle pressure ratios. The quasi-one-dimensional nozzle-flow model is dynamically coupled to a three-dimensional flow solver through source terms in the governing equations, named as dynamically coupled source model. The dynamically coupled source model is then applied to a temporal gas jet evolution case and a cold flow engine case. The results show that the dynamically coupled source model can reasonably predict the gas jet behavior in both cases. All simulations using the new model led to reductions of computational wall time by a factor of 5 or higher.

Investigation of an Experimental Laser Sensor-Guided Spray Control System for Greenhouse Variable-Rate Applications

2019 ◽  
Vol 62 (4) ◽  
pp. 899-911
Author(s):  
Tingting Yan ◽  
Heping Zhu ◽  
Li Sun ◽  
Xiaochan Wang ◽  
Peter Ling
Keyword(s):  
Control System ◽  
Delay Time ◽  
High Speed ◽  
Laser Scanning ◽  
Plant Production ◽  
Laser Sensor ◽  
Variable Rate ◽  
Spray Volume ◽  
Spray Control ◽  
Variable Rate Spraying

Abstract. Precision variable-rate spraying technology is needed for controlled-environment plant production in greenhouses. An experimental spray system for greenhouse applications was developed for real-time control of individual nozzle outputs. The system mainly consisted of a high-speed laser scanning sensor, 12 individual variable-rate nozzles, an embedded computer, a spray control unit, and a 3.6 m long mobile spray boom. Each nozzle was coupled with a pulse-width modulated solenoid valve to discharge sprays at variable rates based on target presence and plant canopy structure. Laboratory tests were conducted to evaluate the accuracy of the spray control system in respect to spray delay time, nozzle activation, and spray volume using four target objects of different regular geometrical shapes and surface textures and two artificial plants of different canopy structures. Other experimental variables included three detection heights from 0.5 to 1.0 m and five sensor travel speeds from 1.6 to 4.8 km h-1. A high-speed video camera was used to determine the delay time and nozzle activation in discharging sprays on target objects after the laser sensor had detected the objects. The detection height and travel speed were found to have slight influence on the timing of nozzle activation. The nozzles started spraying in a range between 33 and 83 mm before reaching the target objects and stopped spraying between 13 and 84 mm after passing the objects, ensuring that the objects were fully covered by the spray. Spray volume corresponded to the object sizes well, and the spray control system performed with higher accuracy at lower travel speeds. Differences between the calculated spray volume based on the sensor detection and the actual spray volume ranged from 1.9 to 2.7 mL per object among all tested objects. The variable-rate control system reduced spray volume by 29.3% to 51.4% for all the objects compared with conventional constant-rate spraying. At the same time, the nozzles could be activated precisely by the object presence. Consequently, this experimental laser-guided system was implemented on a boom system in a commercial greenhouse for future investigations of its accuracy in variable-rate spraying to save pesticides, water, and nutrients. Keywords: Automation, Intelligent sprayer, Pesticide, Precision spray technology, Boom spray equipment.

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