Source: INNOVATIVE SCIENTIFIC SOLUTIONS, INC submitted to
IN-FLIGHT MEASUREMENTS OF SPRAY SYSTEM DROPLET SIZE FOR AERIAL CHEMICAL APPLICATION
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
1009517
Grant No.
2016-33610-25478
Project No.
OHOW-2016-00989
Proposal No.
2016-00989
Multistate No.
(N/A)
Program Code
8.13
Project Start Date
Aug 15, 2016
Project End Date
Apr 14, 2017
Grant Year
2016
Project Director
Crafton, J. W.
Recipient Organization
INNOVATIVE SCIENTIFIC SOLUTIONS, INC
7610 MCEWEN RD
DAYTON,OH 45459
Performing Department
(N/A)
Non Technical Summary
The spray application of pesticides, herbicides, fertilizers and growth regulators produces substantial benefits in crop yields. Aerial spray application of bulk materials offers advantages such as efficiency, speed, and access to constrained areas. However, a disadvantage with spray application is the unintended drift of spray droplets. Spray drift reduces efficiency, increases cost, and produces potential environmental hazards. The key issue is controlling the size of the spray droplets produced by application nozzles in flight. Nozzle performance is routinely characterized in wind tunnels by experimental measurements designed to mimic the in-flight process. However, imperfect models must be used to extend the wind tunnel test results to in-flight performance. This program will develop a droplet size measurement system that can be used in flight. Successful implementation will provide two key opportunities: (1) measurement of droplet size in flight for the development of improved nozzles and application processes, and (2) the potential for closed-loop control of droplet size to reduce spray drift in real time.Innovative Scientific Solutions, Inc. developed Particle Shadow Velocimetry (PSV) as a velocity, acceleration, and particle/droplet size measurement technique. PSV employs high magnification imaging of the shadows produced by flowing droplets or particles. Size measurements have been conducted on water droplets in a Mach 2 wind tunnel, and on propellant grains in an active solid rocket motor. The basic hardware of the proposed system consists of an LED for illumination and a digital camera for imaging. It totally eliminates the bulky and expensive laser components typically used in size measurement systems. As a result, PSV is very suitable for in-flight measurements of the size of agrochemical spray droplets in high speed air. The societal benefits of the overall SBIR Phase I and potential II program are to reduce the quantity of agrochemicals that need to be applied and the resultant environmental hazards from unintended spray drift.
Animal Health Component
20%
Research Effort Categories
Basic
0%
Applied
50%
Developmental
50%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
40453102020100%
Knowledge Area
404 - Instrumentation and Control Systems;

Subject Of Investigation
5310 - Machinery and equipment;

Field Of Science
2020 - Engineering;
Goals / Objectives
Goal: Improve thespray application ofagrochemicals, such as pesticides and growth promoters, by: (1) providing real-time droplet size measurements in flight for optimum application, and (2) providing data to improve the design of spray nozzles and application techniques that minimize drift-sized droplets.Objectives:Design a Particle Shadow Velocimetry (PSV) system for droplet sizing in-flight and construct a prototype system.Demonstrate droplet size, velocity, and acceleration measurements in the laboratory at Innovative Scientific Solutions, Inc. (ISSI) using a sample nozzle from an aerial spray system.Demonstrate droplet size measurements in the wind tunnel at the USDA - Agricultural Research Service, Aerial Application Technology (AAT) Research Unit on several nozzles selected by the AAT team. Compare the results to established protocols and droplet measurement equipment used by the AAT team.Refine the design of the prototype in-flight PSV system for mounting on the AAT AirTractor 402B test aircraft.Perform several flight tests with the AirTractor 402B and acquire droplet size data. Compare the in-flight results to wind-tunnel-based predictions.
Project Methods
Efforts: ISSI has previously demonstrated the ability of our PSV technology to make droplet size, velocity and acceleration measurements on water injected into a Mach 2 flow and on combustion particle dynamics in an active solid rocket motor. ISSI will utilize this knowledge to:Compare several configurations for the in-flight PSV system. Among the more promising candidates are color CCD cameras that have been developed for machine vision and surveillance applications. These packages are small (~ 2-inch cube) and designed to operate in harsh environments like those that will be encountered on a spray rig or in flight. Light-emitting-diode (LED) technology will be used for the multi-color source. Several multi-color LEDs will be combined with a holographic diffuser to provide a small package that can illuminate with 1-microsecond pulse widths. The individual LED dyes of the color unit will be triggered individually to allow the color-PSV approach to be executed.Demonstrate droplet size, velocity and acceleration measurements in a water spray, produced by a representative agrochemical spray nozzle, in bench-top testing at ISSI. Data processing routines will be established with the USDA AAT team that allow the basic PSV data to be pre-processed and formatted to be compliant with their existing procedures.Acquire droplet size and velocity data on several spray units in a wind tunnel at the AAT Research Unit. The previously-selected in-flight PSV system will be installed in the tunnel and droplet size data will be collected.Configure the PSV system for aircraft mounting and operation. The two major issues with flight testing the instrument are mounting the device on the plane, and controlling and collecting the data. We believe that the unit can be constructed and mounted on the spray feed line on the trailing edge of the wing. This should allow the inline optical access for the PSV system. Several options for system control are available. We anticipate a wired Ethernet connection between the camera and the data acquisition control PC in the plane. The data acquisition system will include a triggering capability that will allow the system to be activated with the spray system. The control PC will include a wireless radio, for example a Digi TransPort WR11, which will allow the PC to be monitored remotely from the ground.The final phase of the program is the demonstration of the system in flight on the AirTractor 402B. We anticipate several flight tests comprising approximately 10 hours of aircraft usage. The test data will be processed by ISSI and the final data will be delivered to the AAT team.Evaluations: Three primary evaluations will be enabled by the efforts described above:Effort 2, benchtop testing at ISSI, will be used as a final down-selection for the PSV system hardware as well as to establish data processing procedures for the final system.Effort 3, wind tunnel testing at the USDA AAT, will validate the droplet size and velocity measurements, identify any potential interactions between the PSV system and the spray nozzle before flight testing, and reveal any potential aerodynamics issues associated with the in-flight system.Effort 5, flight testing at the USDA AAT, will allow a comparison of the actual in-flight droplet size and velocity measurements with those that would be predicted based on the wind-tunnel testing. This evaluation will provide an initial validation of the models used to predict in-flight droplet behavior from wind-tunnel tests.

Progress 08/15/16 to 04/14/17

Outputs
Target Audience:The primary target audience is aerial applicators of agrochemicals since the spray droplet measurement and control system is being designed for use on their aircraft. We interacted with this audience at the NAAA AnnualConvention and during development of the Phase II commercialiation plan. Associated audiences include: (1) Distibutors of agrochemical dispersal equipment. They will market and sell the system to the target audience. We worked specifically with Transland LLC, the major US dispersal equipment company and collaborated with them on market analysis, target system pricing, and development of the Phase II commercialization plan. (2) Manufacturers of aerial application guidance systems. The spray droplet size/recommended settingsinformation will be displayed to the pilot via the guidance system. We worked specifically with Dynanav Inc.on the development of system integration plans. (3) The NAAA. They are the professional organization for aerial applicators and provide an excellent channel of information exchange and marketing to the target audience. They provided letters of support and we participated in their 2016 Annual Convention. (4) Insurance providers for aerial applicators. Use of the spray droplet measurement and control system is expected to reduce insurance rates as a history of reduced drift claims is developed. We interacted with representative providers at the NAAA Annual Convention. (5) Agrochemical developers. The spray droplet measurement system will provide a valuable tool for development of application specifications. We interacted with representative providers at the NAAA Annual Convention. (6) The USDA Agricultural Research Service Aerial Application Technology Research Unit. The spray droplet measurement system will provide a valuable tool for validation of wind tunnel testing results and for the development of new aerial application methods and guidelines. This group was a collaborator on the Phase I wind tunnel and flight testing. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This program was not specifically intended to provide training and professional development opportunities. Nevertheless, our participation in the National Agricultural Aviation Association (NAAA)Annual Convention, and our extensive interactions with Transland LLC, Dynanav Inc., the USDA AAT, and a number of aerial applicators, significantly increased our understanding of the aerial application domain and product design requriements to meet theseuser's needs. How have the results been disseminated to communities of interest?Program objectivesand preliminary results were provided to several target audiences at the NAAA AnnualConvention in December 2016. Since that time we have provided an updated program summary for use by the NAAA Technical Committee. Detailed test results have been provided to our collaborators at the USDA AAT. Program summaries have been provided to Transland LLC, Dynanav and aerial applicators offering to participate in the proposed Phase II program. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Project Impact The prototype demonstrated under this Phase I SBIR is a system for optimizing spray system performance on agrochemical application aircraft, commonly known as "crop dusters". Current technology allows applicators to precisely control their location and flight path (GPS guidance), to deal with changing temperature, humidity and wind conditions (Aircraft Integrated Meteorological Measurement System modules), and to control important properties of their chemical mixes. However, it does not allow them to monitor and control a key application parameter, spray droplet size. If the droplets are too small, they drift to unintended locations; if they are too large, plant coverage is poor. The EPA estimates that chemical drift losses exceed $200M annually. Drift litigation claims are also a multi-million-dollar annual cost. Crop loss, environmental damage, and human health costs are other significant impacts of poor droplet size control. This SBIR program is providing the missing link: real-time, inflight, droplet size feedback. It will enable applicators to adjust system pressure and airspeed, in flight, to achieve the desired droplet spectrum. It will allow them to verify the effectiveness of between flight changes such as nozzle settings and chemical mixes. Operators will now be able to "close the loop" on the key droplet size parameter. Automation of the control process may be possible in future product versions. The savings achieved in chemicals, time, litigation avoidance, and flexibility in optimizing chemical mixes are projected to afford a payback time of less than one year to aerial applicators who purchase the system. The product will be sold as an add-on to new systems or as a retrofit to existing systems. It will not impact the design, usage, or cost of other spray system and aircraft components. After the one-year payback, applicators can pass on a share of their savings to their customers, the U.S. farming community. The impact of poor spray control is not always reflected as drift off the farmer's fields. It often shows up as uneven application within the field, which results in diminished product effectiveness and crop losses. Although we have not attempted to quantify the costs, the impact of agrochemical drift on human health and the environment are known to be significant. The EPA, USDA, FDA and HHS all have monitoring programs, guidance manuals, or reporting requirements associated with the issue of chemical drift. The proposed program will provide payoffs that are directly responsive to these agency and national needs. The program represents a signficant commercial opportunity for ISSI and our partners. It will open a $25M market, in the U.S. alone, for our product distributor, Transland LLC. It will provide an opportunity for ISSI to double our current annual commercial sales. Because of the maturity of the fundamental measurement system, we are structuring the program to begin commercial sales immediately after Phase II, if we are selected for an award. AccomplishmentsRelated to ProjectObjectives 1 & 2. Design and demonstrate a spray droplet size measurement system for use in flight: Our initial efforts to develop a flight capable droplet sizing system were focused on bench testing of a variety of cameras, lenses, and LEDs to determine the optimal configuration for this application. To accomplish this, a small wind tunnel was constructed using a 7.5 horsepower blower connected to a 4.5" x 4.5" x 24" aluminum test section with acrylic windows on two sides, and an aerial spray nozzle.After extensive testing of multiplePSI (technology name changed to Particle Shadow Imaging, since no velocity measurement are being made) configurations, the Basler Ace 2040-90um camera was selected, along with an ISSI custom pulsed LED. The Basler Ace has a small form factor of approximately a 1" cube, 4-megapixel resolution, and low power requirements, making it ideal for a flight environment. A pulsed LED was selected to minimize blurring of the water droplets in the images. In addition to optimizing the hardware configuration, significant effort was focused on the image processing software. The resultant program automatically reads the images, detects in-focus droplets while rejecting those that are too out of focus for accurate sizing, sizes individual droplets, and calculates size distribution statistics such as Dv10, Dv50, and Dv90. 3. Demonstrate droplet size measurements in the wind tunnel at the USDA Agricultural Research Service, Aerial Application Technology (AAT) Research Unit: ISSI and USDA personnel jointly tested the system against the standard Phase Doppler Particle Analyzer (PDPA) droplet sizing system in the high-speed aerial spray wind tunnel.Data were collected using a 4010 flat fan nozzle, two airspeeds, two nozzle pressures, water alone, and water with the addition of 0.25% by volume of Wilbur-Ellis R11 90% NIS adjuvant to better simulate typical agricultural sprays and for direct comparison of the PSI data to the USDA's High Speed Nozzle Model. The trends with nozzle pressure and airspeed were largely consistent between the PDPA and PSI datasets. 4 & 5. Refine the design and test in flight on the AAT AirTractor 402B test aircraft. After processing the USDA wind tunnel data and making some minor changes to the PSI system, the droplet sizing system was mounted to the spray boom of the AAT's AirTractor 402B with custom aluminum struts machined by ISSI. The PSI system was very stable in flight with no issues caused by vibration or drag. A direct comparison between in-flight and wind tunnel data for the 4010 nozzle found amaximum difference in Dv values of14.3%. Seven of the 12 measurement comparisons had a difference of less than 5%. Further exploration of the discrepancies between wind tunnel and flight test results will be addressed in the proposed Phase II testing. These discrepancies may not represent measurement errors; they may reflect differences in spray droplet formation in a wind tunnel versus flight. Overall, the PSI data from the wind tunnel is in reasonable agreement with PDPA data, and the in-flight PSI data is in reasonable agreement with the PSI wind tunnel data. These results demonstrate that the PSIsystem is generating the required droplet size data in-flight. The primary goal of the Phase I program was accomplished, namely to demonstrate the ability to measure droplet size distributions in-flight. To our knowledge, this is the first time experimental measurements of droplet size have been acquired in flight. 6. Additional objective accomplished: Initial redesign of the PSI system to address the anticipated commercial requirements. The redesign of the PSI system incorporates allmeasurement and computationalcomponents in two small modules on the brackets that mount the system tothe aircraft spray boom. The only connection to the fuselage will be a power line and a data feed line to the guidance system.If it isnotnecessary to hard wire the connection to the guidance system, WiFi or Bluetooth can be provided. A Jetson TK1 micro-PC was selected to enable real-time droplet size computations. The guidance system display will provideinformation to the pilot so that no additional cockpit instrumentation is required.During the proposed Phase II program we plan to develop algorithms that use the droplet sizedata to recommended specfic spray system and airspeed adjustments that can be made in flight in order to keep the droplet spectrum in the desired range. This approach will significantly aid the pilot and increase system effectiveness.

Publications


    Progress 08/15/16 to 04/14/17

    Outputs
    Target Audience:NIFA USDA Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?ISSI is currently evaluating the need for additional wind tunnel and/or flight testing under the Phase I program. The primary objective of the Phase I program has been accomplished: obtaining droplet size measurements in flight. However, it may be desirable to collect additional data to compare the PDPA system and PSI system in the wind tunnel, and the PSI system in the wind tunnel and in-flight. If it is concluded that additional testing is required, and that the USDA ARS AAT can support it, ISSI will return to College Station early in CY 2017. ISSI will continue development of the commercialization plan for the droplet sizing system. ISSI is continuing our discussions with several groups interested in participating in the development of the system during Phase II. These discussions are key to ensuring that we develop a product that is useful and feasible for commercial applications. How have the results been disseminated to communities of interest? ISSI is actively participating in the USDA CAP1 program to ensure development of a viable commercialization plan for the Phase II proposal. As mentioned earlier, ISSI is closely engaged with Transland LLC, the leading US supplier of agrochemical dispersal equipment. Because ISSI does not have an established presence in the aerial application marketplace, we envision Transland providing this presence and serving as distributor of the commercial products. Our Phase I market analysis efforts included participation in the National Agricultural Aviation Association (NAAA) annual meeting in December, 2016. We assessed interest in a commercial in-flight system with aerial applicators, application guidance system manufacturers, agrochemical developers, and insurance providers. The interest was extremely positive because of its potential to: 1) ensure that applicators are conforming to agrochemical label guidelines, 2) improve application efficiency and reduce drift potential, 3) to reduce regulatory oversight and litigation claims, and 4) to reduce insurance rates for applicators. To paraphrase one aerial applicator: "I can perform spray pattern testing in the morning (conducted using ground-based collection strings and cards), but later in the day when conditions have changed, I have no way to determine if my patterns are the same". Discussions with these participants also indicated that high reliability, low maintenance and an acceptable price point are key factors for this market. ISSI is actively working these issues with Transland. Since the NAAA meeting we have been contacted by an aerial guidance system manufacturer stating their interest in working with us on integrating droplet size information into their displays. Our market analysis has not identified any other firm that is planning or developing a competing droplet measurement system. What do you plan to do during the next reporting period to accomplish the goals?ISSI is currently evaluating the need for additional wind tunnel and/or flight testing under the Phase I program. The primary objective of the Phase I program has been accomplished: obtaining droplet size measurements in flight. However, it may be desirable to collect additional data to compare the PDPA system and PSI system in the wind tunnel, and the PSI system in the wind tunnel and in-flight. If it is concluded that additional testing is required, and that the USDA ARS AAT can support it, ISSI will return to College Station early in CY 2017. ISSI will continue development of the commercialization plan for the droplet sizing system. ISSI is continuing our discussions with several groups interested in participating in the development of the system during Phase II. These discussions are key to ensuring that we develop a product that is useful and feasible for commercial applications.

    Impacts
    What was accomplished under these goals? Initial efforts to develop a flight capable droplet sizing system were focused on bench testing of a variety of cameras, lenses, and LEDs to determine the optimal configuration for this application. To accomplish this, a small wind tunnel was constructed using a 7.5 horsepower blower connected to a 4.5x4.5x24" aluminum test section with acrylic windows on two sides. The maximum operating speed was 140 mph. Pressurized water was injected through a single aerial spray nozzle mounted in the center of the test section. The small size of the test section, which restricted the spray from developing as it would in flight, was not a concern as the primary purpose of these bench tests was to down-select between multiple PSI configurations and test the operation of the system prior to evaluation in the larger USDA ARS AAT high speed wind tunnel. After successfully designing and performing initial bench tests of the droplet sizing system at ISSI headquarters, the system was transferred to the USDA ARS ATT facility in College Station, Texas. ISSI and USDA personnel jointly tested the system against the standard PDPA droplet sizing system in the high-speed aerial spray wind tunnel. For these tests, the camera and LED were enclosed in waterproof aluminum enclosures to protect the electronics from the spray and airflow. Two rounds of testing were performed in the wind tunnel. In the first, the PSI and PDPA systems were run back to back while tap water (no additives) was sprayed though a 4010 flat fan nozzle. Data were obtained at two airspeeds (120 and 160 mph) and two nozzle pressures (30 and 60 psi). In the second test, 0.25% by volume of Wilbur-Ellis R11 90% NIS adjuvant was added to better simulate typical agricultural sprays, and for direct comparison of the PSI data to the USDA's High Speed Nozzle Model (created using PDPA data). These tests were also run with a 4010 flat fan nozzle. However, the pressure was kept to 40 psi for all tests, and the velocity was varied between 45-180 mph. For both tests, the long flat part of the flat fan spray was aligned with the image plane. Additionally, the nozzle was traversed vertically allowing the camera to view the entire span of the spray, maximizing the amount of spray observed by the camera. The PSI system in the configuration used for these tests detected droplets between approximately 10-2000 μm. The minimum size detected using PSI (~10 μm) is greater than that possible with the PDPA system (< 1 µm). This partially explains why the Dv10, Dv50, and Dv90 values measured by the PSI system were typically greater than that those measured by the PDPA system, as shown in Figure 1. However, the general trends with nozzle pressure and airspeed were largely consistent between the PDPA and PSI datasets. This is evident in Figure 1 where both the PDPA and PSI data show decreasing volume mean diameter (Dv50) values with increasing airspeed, especially at higher airspeeds. After processing the USDA wind tunnel data and making some minor changes to the PSI system, the droplet sizing system was mounted to the spray boom of the USDA AAT facility's AirTractor 402b with custom aluminum struts machined by ISSI (Figure 2). Note that this prototype system is much larger than the commercial system will be. A remote data acquisition system was mounted in the second seat of the AirTractor, allowing ISSI personnel on the ground to control the PSI system in flight. Overall, flight testing went smoothly. The PSI system was very stable in flight, with no issues caused by vibration or drag. Remote operation of the system was straightforward, with only minor connectivity issues occasionally requiring troubleshooting. Flight tests were run on two nozzles--a 4010 flat fan nozzle and a steel disc core nozzle. Both nozzles were run at an indicated airspeed of 120 and 140 mph with nozzles pressures of 40, 60, and 80 psi. Note the 80 psi case was only run at 140 mph because the system could not reach this high-pressure case at 120 mph. Water with no additives was used for all flight tests. The droplet size distribution for steel disc core nozzle was obtained in-flight using the PSI technique. For this particular test, over 16,000 individual droplets were detected and sized. Note that no wind tunnel testing with the PSI system was performed on the steel disc core nozzles at the time of this report. Comparisons have been made between the flight test data and the USDA High Speed Nozzle Model, based on PDPA data taken in the wind tunnel. However, that data was taken with an adjuvant additive while the flight data was taken with no additives, which may cause significant discrepancies in the results. A direct comparison between the in-flight data and wind tunnel data for the 4010 nozzle is shown in Table 1. The maximum difference observed between the Dv values for the wind tunnel and flight test was 14.3%. Multiple factors likely contributed to this difference including: Differences in the upstream geometry and flow environment. Measuring only a single plane of the spray for the flight tests versus traversing the entire spray for the wind tunnel tests. The measurement location for the wind tunnel tests was 18" downstream of the nozzle versus 17" for the flight test. The camera was perpendicular to the spray fan for the flight test and parallel for the wind tunnel test. The camera resolution was slightly different, allowing the wind tunnel testing to detect smaller droplets. In addition, since the airspeed and nozzle pressure conditions were not perfectly replicated between the two tests, linear interpolation of the Dv values was required. Since the trends with airspeed and nozzle pressure are not necessarily linear, this may introduce additional error. Table 1: PSI flight test vs. wind tunnel results for the 4010 flat fan nozzle. Note both tests were run using water with no additives. Flight Test Data Wind Tunnel Data % Difference Test # TAS (mph) Pressure (psi) Dv10 Dv50 Dv90 Dv10 Dv50 Dv90 Dv10 Dv50 Dv90 Run1 125 40 339 571 901 311 564 905 8.5% 1.2% -0.4% Run2 146 40 301 484 729 276 485 799 8.4% -0.2% -9.6% Run3 125 60 323 567 914 314 579 921 3.0% -2.2% -0.8% Run4 146 60 297 482 741 292 513 847 1.8% -6.6% -14.3% Conclusive determination of the cause of the discrepancies between wind tunnel and flight test results will require further testing. The reader should note that these discrepancies may not represent measurement errors; they may reflect differences in spray droplet formation in a wind tunnel versus in flight. Regardless, the primary goal of the initial flight tests, namely to demonstrate the ability to measure droplet size distribution in-flight, was accomplished. Figure 1: Droplet volume mean diameter as a function of airspeed for both Shadow Data (PSI) and the USDA Nozzle Model (PDPA). PSI tests were run at 40 psi with the 4010 flat fan nozzle and 0.25% by volume of Wilbur-Ellis R11 90% NIS Adjuvant added to water. Figure 2: Prototype PSI droplet sizing system mounted to the AirTractor 402b spray boom. Note the prototype system is much larger than the planned commercial sensor.

    Publications