The ERC-FLOVIST project has focused on advancing Tomographic Particle Image Velocimetry (PIV) towards a versatile technique for the non-intrusive diagnostics of aero-acoustic problems. One of the milestones has been the use of Tomo-PIV to infer the instantaneous three dimensional pressure field from the velocity measurement. The use of this laser-based technique for the detection of pressure fluctuations both around and on the surface of aerodynamic models offers the advantage that surface pressure transducers do not need to be installed, along with connecting cables for power supply and data transfer. The technique has demonstrated high scalability and pressure fluctuations were detected from low-speed up to the supersonic flows. This is an important headway from standard technologies (surface pressure transducers and microphone arrays) favouring a broader utilization of PIV in aero-acoustics, flow-induced vibrations and bio-fluid mechanics. The potential of this innovative approach has been recognized in science. However, the industry lags behind with a more conservative position, partly justified by system complexity and the high skills required to perform experiments. Instead, when correctly implemented this method can lead to important economical benefits with saving of costs for the integration of instrumentation. The targeted industrial areas are: aeronautics (aircraft aerodynamics and propulsion), energy systems (turbo machinery and wind energy). In wind-energy, the study of unsteady loads may lead to designs that reduce fatigue loads and increase system durability. Also, growing interest in noise emissions from wind turbines requires increased capabilities for their aero-acoustic analysis. The proposal intends to move forward these capabilities from research labs to industrial facilities. The main task is bringing together the current advances of the Tomo-PIV technique to make it broadly usable by research centres and for industrial innovation.

This proof of concept (PoC) project seeks to explore the possibility of commercializing an optical imaging instrument with the unique ability of permitting a single detector to acquire and store several images simultaneously. This new concept, which is named Frequency Recognition Algorithm for Multiple Exposures (FRAME), employs an "image-coding" strategy, where different exposures are given a unique structural “code”. Thanks to this novel coding approach, the camera sensor may be exposed to light several times before readout is necessary – a completely new feature within the field of optical imaging. The ability for a single detector to acquire a number of images simultaneously opens up for a variety of new measurement schemes such as: 1) Ultra-high-speed videography 2) Instantaneous three-dimensional imaging 3) Simultaneous multispectral imaging. The main goal of the ERC Starting Grant funded project “Spray-Imaging” is to develop and apply new optical imaging approaches for the detailed characterization of atomizing spray systems. The need for both ultra-high-speed and three-dimensional (3D) imaging are then of importance especially for the study highly transient two-phase flow phenomena. This PoC will focus both on the development of both a prototype instrument and a control software. Our business idea is to produce an optical instrument – an “add-on” device – that will permit the user to incorporate the FRAME imaging concept. This approach will allow users to seamlessly upgrade any given optical arrangement (e.g. for any given illumination source and detector) with the FRAME functionality.

Short and slim aero-engine intake designs for very high bypass ratio configurations cause notable levels of unsteady distortions at the fan face especially under cross-wind or angle of attack operation during aircraft take-off. Such distortions can adversely affect the engine’s performance, operability, structural integrity and safety margin with potentially catastrophic consequences for the entire propulsion system. Current practices for aero-engine testing and certification rely on a low number of intrusive pressure measurements at the fan face to characterise the distortion levels. Given the known limitations of currently used methods (low spatial resolution, intrusive nature) the existing technologies are inadequate to reduce the risk on the development and certification of future novel systems. NIFTI aims to address this gap by demonstrating a non-intrusive technique to measure velocity fields across a plane located upstream of a large diameter fan of a high bypass ratio aero-engine which has never been achieved. This method will provide synchronous datasets across the measurement plane with at least one order of magnitude higher spatial resolution than current methods. The implementation will demonstrate a highly automated and flexible multi-camera system within a representative industrial test environment. A number of more advanced, non-intrusive measuring technologies will be assessed such as 3D PTV or Helium Filled Soap Bubbles (HFSB) to further enhance the outputs of the selected baseline solution. The experimental activities will be supported by numerical campaigns and advanced data processing and flow analysis methods that will be used to analyse the highly unsteady nature of the flow distortions that will be measured during NIFTI’s experimental campaigns. These outcomes will ultimately unlock the complex aerodynamics of closely coupled fan-intake systems and aid the development of novel design rules for future, stall-tolerant aero-engines.

HOMER is aiming at the development of non-intrusive experimental flow diagnostic and data assimilation methods to expand capabilities from the aerodynamic analysis to the investigations of fluid-structure-interactions (FSI) in wind tunnels and other test facilities. The objective of the project is to develop an unattained combined diagnostic approach with simultaneous optical measurements of fluid and structure. When this is achieved, the measurements can be treated invoking the relation between the balancing forces (inertia-, elastic- and aerodynamic forces) interacting (non-linearly) within the s.c. Collar Triangle (FI + FE + FA = 0). The research focuses on the application and further development of time-resolved volumetric (4D) flow field measurements that enable determining the fluid flow pressure. 3D PIV and Lagrangian Particle Tracking (LPT) along with Digital Image Correlation (DIC) are tailored to determine the position and dynamics of fluid and surface motion and deformations. Pressure Sensitive Paint (PSP) methods will be employed simultaneously with DIC and PIV/LPT to obtain the surface pressure at transonic flow velocities together with the model deformation. The project realizes experiments that support the validation needs of MDO tool developments, enhance the physical knowledge about Fluid-Structure-Interaction phenomena and range from the assessment of the method (turbulent flow over a deforming surface) to relevant problems in aeronautics (transonic buffeting) and flapping flight mechanics.