Visualization of High Speed Liquid Jet Impaction on a Moving Surface
April 17th, 2015
Two experimental devices for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device and a spinning disk device. The apparatuses are used to determine optimal approaches to the application of liquid friction modifier (LFM) onto rail tracks for top-of-rail friction control.
The overall goal of the following experiment is to study the impaction of a free surface liquid jet on high speed moving surfaces. This is achieved using two different apparatuses. The first is a spinning disc with a top speed of 100 meters per second, onto which a nozzle sprays a liquid jet.
Video cameras capture the liquid impact on the surface for later analysis. The second apparatus is a rail gun powered by compressed air capable of firing a projectile at up to 25 meters per second. The projectile passes below an orifice from which a thin stream of liquid is forced.
A camera captures video for analysis of the impact. Next, the video is analyzed and the jet surface impact is characterized and quantified. The results show there are three different types of impact behavior, and that the transitions between these behaviors depend on several variables.
This method can help us answer some key questions in the area of free surface fluid mechanics, specifically concerning the spreading characteristics of a free surface leakage at impacting on a moving surface. It can also be used to study the fluid mechanics of moving contact lines. This video starts at the spinning disc apparatus after preparation of the test fluid.
This schematic provides an overview of the system. A disc is driven by a variable frequency drive electric motor. A nozzle is positioned to force a jet of test fluid onto the disc surface.Cameras.
Record the fluid surface interaction action. Begin to check the apparatus by first ensuring that the air supply valve for the air bearing is open. The pressure gauge should be in the range of 60 to 80 PSI gauge pressure.
Next, clear anything that might impede the motion of the disc and turn the disc. Several rotations in each direction to check for any problems. Move on to work with the test fluid system.
Lean and secure the compressed gas accumulator used for test fluid pressurization. When ready, get three kilograms of test liquid or the liquid into the fluid port of the accumulator with the fluid in place. Continue to make the necessary connections First.
Connect the gas port of the accumulator to a nitrogen tank by a pressure regulator. Then connect the fluid port of the accumulator to the jet spray nozzle. Next, start the control software for the disc and the drive proceed by checking the two movie cameras.
Each has a high magnification lens and is placed 35 centimeters from the jet impingement point, each captures a different view. Position a 150 watt fiber optic light source to achieve an evenly lit background testing can begin. Once all the system components are ready.
Use the variable frequency drive controller to set the disc speed to the desired value. Here about 1000 RPM in the control software. Click the test sequence button to start the automated test.
During the test, the software determines the optimal parameters. Monitors the surface speed, nozzle back pressure, and temperature, and triggers the cameras on completion of the test. Save the video and other data experiments can also be conducted using an air cannon.
The air cannon consists of a steel barrel, which is pressurized by an air tank. The projectile is made of wood with a metal top surface onto which the liquid jet will impact A nozzle above the barrel. Provides the fluid jet.
Now get three kilograms of prepared test fluid, pour it into the fluid port of the accumulator. When done, connect fluid port of the accumulator to the jet spray nozzle and connect tubing from accumulator gas port to a nitrogen cylinder. Fire a pressure regulator.
Complete the fluid preparation by setting the accumulator pressure about 40 PSI. For this video, turn on the controller software. Then get the projectile and insert it into the canon barrel.
Move the stop mechanism to the barrel exit. Next, open the pressurized airline leading to the air tank. Pressurize the tank in the range of 30 to 70 PSI to produce the desired projectile velocity.
At this point, check the video capture setup for video capture. Have a high speed camera positioned next to the jet spray nozzle and a diffusion sheet across the air gun barrel from the camera. Secure a high intensity fiber optic light to shine through the diffuser to illuminate the impingement site.
Once everything is in place, put on air moss for protection from the air cannon blast. Access the Cannon Control panel and press the warning button to signal the start of an experiment. Push the Air Gun Control panel button to fire the projectile and the air Canon automated control system and coordinate each component of the apparatus.
To complete the test for data analysis, use a computer equipped with software for viewing the high speed recordings for a given test condition. Play the impingement video at normal speed to observe and record the behavior of the jet. After calibrating the image scale, identify an interval in the video.
When the jet appears most stable, begin measuring and recording the dimensions of interest from the impact. In this case, the software is used to determine the lamella stagnation point radius. Complete the measurement of all dimensions before proceeding.
Next, advance through 100 frames of the images. Repeat the measurements to confirm that the jet and lamella are stable. There are three main behaviors associated with liquid jet impingement on moving surfaces, deposition splatter, and splash.
These examples still images were obtained from video recordings during experiments in which the jet flowed in a straight, steady stream towards the surface. In deposition, the jet adheres to the surface and remains on the surface. For the remainder of the experiment, splatter and splash occur when the liquid jet only partially adheres to the impingement surface.
The transition between deposition behavior and splatter or splash is a function of many variables, including the jet diameter, the jet and surface speeds, the jet viscosity, the surrounding air pressure, and even the roughness of the surface. For example, in this video, jet deposition is observed as the jet strikes the first surface with a roughness of 510 nanometers and a second surface with a roughness of 160 nanometers. In contrast, splash occurs when the jet impacts a third surface with a roughness of 16 nanometers.
The impaction of a liquid jet on a moving substrate is physically highly complex. The apparatus is showing this video permit one to study jet impaction in a controlled scientific manner.
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Overview
This study investigates the impact of liquid jets on high-speed moving surfaces using two experimental devices: a spinning disk and an air cannon. The goal is to optimize the application of liquid friction modifiers on rail tracks for improved friction control.
Key Study Components
Area of Science
- Fluid dynamics
- Surface interactions
- Friction control
Background
- Liquid jet impingement is crucial for various industrial applications.
- Understanding the dynamics of liquid impact can enhance surface treatment methods.
- Friction control on rail tracks is essential for safety and efficiency.
- Two distinct apparatuses provide different insights into liquid behavior on moving surfaces.
Purpose of Study
- To analyze the effects of liquid jet impingement on high-speed surfaces.
- To determine optimal methods for applying liquid friction modifiers.
- To enhance the understanding of liquid dynamics in practical applications.
Methods Used
- A spinning disk rotating at 100 meters per second with a liquid jet nozzle.
- A rail gun that fires a projectile at 25 meters per second, releasing a liquid stream.
- Video analysis of liquid impact on surfaces for data collection.
- Comparative analysis of both apparatuses to evaluate performance.
Main Results
- Both devices effectively demonstrate liquid jet behavior on moving surfaces.
- Data indicates optimal conditions for liquid application on rail tracks.
- Video analysis provides valuable insights into liquid impact dynamics.
- Results contribute to improved friction control strategies.
Conclusions
- The study successfully characterizes liquid jet impingement on high-speed surfaces.
- Findings support the development of effective liquid friction modifier applications.
- Future research can build on these methods for broader industrial applications.
Frequently Asked Questions
Executive Industry Relevance
Quantitative visualization of high-speed liquid jet impaction on moving surfaces enables precise characterization of deposition, splatter, and splash regimes critical for process engineering. This capability supports predictive confidence in surface-liquid interactions relevant to advanced manufacturing and material processing. The method's reproducibility and control over key variables position it as a foundational tool for de-risking early-stage industrial workflows.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables mechanistic interrogation of fluid-surface interactions under controlled, high-speed conditions.
- Supports de-risking of process variables by isolating effects of jet speed, surface roughness, and fluid properties.
- Facilitates hypothesis-driven studies on deposition versus splash outcomes for material interface optimization.
Screening & Assay Development
- Provides standardized, reproducible platforms for evaluating liquid deposition on engineered surfaces.
- Generates quantitative video and pressure data for robust assay development and cross-condition comparison.
- Enables scalable screening of surface treatments or formulations for optimal deposition behavior.
Translational & Preclinical Research
- Aligns experimental outputs with industrial process requirements for surface coating and additive manufacturing.
- Supports continuity from discovery-phase mechanistic studies to preclinical process validation in relevant systems.
- De-risks scale-up by providing predictive data on fluid behavior across variable surface speeds and textures.
Pipeline & Workflow Integration
This method integrates into the discovery-to-preclinical continuum by enabling controlled hypothesis testing of liquid-surface interactions, supporting both early mechanistic studies and downstream process optimization.
- Discovery Biology: Quantifies the impact of independent variables such as jet speed and surface roughness on deposition outcomes.
- Screening: Delivers reproducible, quantitative outputs (e.g., lamella radius, splash threshold) for cross-condition analysis.
- Analytics: Provides high-speed video and pressure data to support statistical comparison of impact regimes.
- Translational Research: Bridges laboratory findings to industrially relevant surface speeds and conditions.
- Enterprise Reuse: Offers a modular, adaptable platform for repeated mechanistic and process studies across R&D teams.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence in fluid-surface interaction outcomes and reduces mechanistic ambiguity.
- Operational Value: Standardizes experimental conditions for reproducibility and scalability across projects.
- Strategic Value: Informs go/no-go decisions for process development and material selection, reducing late-stage risk.
- Portfolio Impact: Enables risk-adjusted prioritization of surface treatment and deposition technologies.
Implementation Considerations
- Requires expertise in high-speed imaging, fluid mechanics, and quantitative video analysis.
- Demands access to precision-controlled apparatuses and synchronized data acquisition systems.
- Necessitates cross-team standardization of measurement protocols and data interpretation.
- Adaptable to a range of surface materials and fluid formulations with appropriate calibration.
- Practical limitations include upper bounds on surface speed and jet stability as defined by apparatus design.
