Rainfall passing over a given area is a highly dynamic process; it changes constantly in form and intensity. It varies constantly on short spatial and temporal scales that makes real time measurements of the amount of rainfall challenging. Measuring and sensing rain is important to be able to understand and control our urban environment. Traditionally, rainfall analysis for hydrologic modelling use spatial measurements collected at various sparsely spread observation points using rain gauges working on various principles such as weighing type, tipping bucket, capacitive type etc. An accurate representation of spatial model of rainfall is essential for hydrological operational purposes such as forecasting of river flow, flood irrigation planning and modelling of catchment areas. Measurement of drop size distribution are also exploited to investigate microphysics of precipitation and to improve rainfall remote sensing estimation techniques. However, the high initial costs of convectional rain gauges prevent collection of data with high spatial resolution. The research looks at investigating the sensor stack to be a part of an integrated sensor approach to develop a device architecture for the development of low cost integrated rain sensing and measuring the rain. The device architecture consists of three main stacks – energy generation layer, sensing layer, processing layer. The raindrop on impact causes vibration on the device surface. This force exerted by the raindrop causes a deflection and is measured indirectly by the use of a thin film piezo sensor. As part of the work, we find there is a good correlation between the vibrations caused and the size or volume of the raindrop by indirectly measuring the impact force of the raindrop. The working range of the device is between 100hz and 2000hz, which includes the first modal peak of the impact that acts as an amplification to the drop's impact. Using this information, the device is able to calculate the raindrop size distribution and the rain intensity. Calibration of the device is key as we are measuring the impact force of the rain drops and correlating it to the size of the drop. Primary, not all rain drops will fall on the device at terminal velocity (the main assumption for calibration of the device), as the fall velocity of the droplet may also be affected by the wind. Secondly, the spatial variation of the frequency response function in Volts/Newton in decreasing order from the centre of the plate.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:658735 |
| Date | January 2015 |
| Creators | Kundgol, A. S. |
| Publisher | University of Salford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://usir.salford.ac.uk/35418/ |
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