Description

Water surface measurements of turbulent free surface flows are animportant part of hydraulic measurements. It is crucial to perform precise and reliable measurements of hydraulic phenomena. Conventional measurement methods fail in the case of two-phase flow and don´t allow for the reliable dynamic measurements with high spatial resolution.

Interpretation of LIDAR measurements will be performed by optical flow modelling of successive LIDAR laser beam reflections. This will make it possible to recognize the water surface properties. Optical flow algorithms provide an estimation of a sequence of specular reflections within the aerated flow surface. Exact representation is, however, impossible due to the highly turbulent nature of the fluid flow. In addition to the measurements of aerated water surface properties, we are going to measure a raw signal from LIDAR using waveform digitizing system or fast oscilloscope. The signals will be then processed on personal computer by using signal processing algorithms in time and frequency domains. In such a way by the LIDAR measured depth profile will be extracted and correlated with the one measured with the reference optical systems.

Main goals

The project aims to develop knowledge and improve LIDAR operation for highly aerated turbulent free surface flow. We will develop a model that relates the state of the water surface to the optical flow of LIDAR beam at successive reflections from bubbles´ surfaces at the water surface. A model of successive specular reflections will be provided, which will enable later implementation within the newly developed prototype WS-LIDAR. With a capability to measure solid surfaces and aerated turbulent water surfaces the prototype WS-LIDAR device will greatly surpass current LIDAR capabilities. With measurements of turbulent, aerated water flows, we will perform a calibration of 3D numerical CFD models, which cannot simulate such flows with satisfactory accuracy without the available calibration data.

Project work packages:

• WP1. Requirements and specifications
• WP2. Modelling
• WP3. Experimental work
• WP4. Synthesis and implementation in a WS-LIDAR
• WP5. Dissemination, exploitation and demonstration