Fluid Mechanics Measurements in Real-World Environments
For fluid mechanical design in product development, experience and solid engineering know-how are required. Typically, in a first step, all relevant information about the product’s requirements, the involved processes and the lessons learned from precursors are carefully collected and analyzed. The design process then includes system modelling and flow simulation, an optimization loop and finally the experimental validation. In terms of cost, the experimental verification step represents a significant part of the overall project budget.
According to our experience at streamwise, gained from many industrial projects, only a few quantities at discrete locations are required to verify design, modelling, and performance. If the validation experiments are designed correctly, otherwise large campaigns can be substituted with relatively low-cost targeted measurements.
Precisely targeted measurements require specific sensors. In many cases, off-the-shelf components are not a good fit in terms of size, installation effort, and performance. streamwise has developed a modular, wireless sensor platform which incorporates the following features:
- Miniature battery powered for wireless application and easy installation
- Virtually unlimited number of sensor nodes in the network
- Wireless time-synchronization of the sensors
- Real-time wireless data transfer to data acquisition PC
- On-board data logging to mitigate radio link black-outs
- Standard digital bus system for easy integration of a multitude of sensors
- Modular electronics layout to allow different form factors
- Sensor dimension example (varies depending on particular application) 3x3x2 cm
With the modular setup, the capabilities of the platform can be adapted to a multitude of measurement tasks. Some application examples of customer-specific validation measurements are listed below.
Fluid Mechanics Measurements – Application Examples:
- Wind speed measurements at tunnel entry
When a train enters a tunnel portal, the local flow velocities can reach levels that are considerably higher than the actual speed of the train. The wind speed at the pantograph of a train is critical for its performance and needs to be assessed. To this end, the wireless measurement platform was adopted for the transient measurement of local flow velocities at the pantograph. A classical pitot tube and the necessary pressure sensors were selected and integrated to the measurement platform. The battery power management and the measurement software were adopted according to the requirements. All components were protected by a watertight housing. The resulting sensor module can easily be installed (no wires allowed in this high-power environment) days before the measurements took place which simplified scheduling. Data can be collected at 100 Hz and logged onboard for 48h. Sensor standby time is much longer with start and stop signals being sent over the network. Measurement data can be downloaded after or in-between the measurements.
- Oxygen measurements for Modified Atmosphere Packaging (MAP)
To increase the shelf life of goods affected by Oxygen (e.g. coffee) the air in the container is substituted with inert gases. This needs to be carefully adjusted and controlled for efficiency and quality of the packaging process. It is possible to fit the measurement platform even in packages as small as coffee capsules. This opens up opportunities for applications in the packaging industry. Inline-measurements (placing the sensor inside the product during the packaging process) can provide stunning insights into the packaging process!
Equipped with a custom-made sensor for Oxygen measurements, our wireless platform is used to determine the Oxygen levels in a coffee capsule while traveling through a packaging machine. With precise time and position resolved Oxygen levels available in real-time, optimizing the packaging process becomes straight forward. Moreover, quality assurance, i.e. local maximum Oxygen levels the product is exposed to is achieved.
- Transient pressure measurements
Equipped with a pressure sensor for liquid applications and housed in a stainless steel sealed container, the sensor platform can measure transient pressure in closed liquid containers. Again, with the approach to investigate a process from the product’s viewpoint, the bottling of liquids in e.g. PET bottles can be analyzed.