Objectives

Fan is the turbomachine engineers designed, and manufacturers realized, in varieties of shapes, configurations and sizes, that do not find equal in terms of design challenges and manufacturing issues. This, still today, makes fan aerodynamics the first crucial challenge of fan technology, the first knowledge each fan designer and manufacturer must command to properly deal with fan noise and structural issues, as well as with fan application and systems.

Accordingly, the track is dedicated to the fan aerodynamics in its wide spectrum: from the aerodynamic design methods to practical design examples of new generation industrial fans, from the experimental techniques to the computational methods suited to study and quantify the global fan aerodynamics and details of the local flow field and how they are affected by either unsteady phenomena or inlet flow distortions, from the fan selection criteria to the basics of preliminary sizing, from the aerodynamic performance optimization techniques to the new frontiers made available by artificial intelligence for the fan technology.

Particular emphasis will be given to the following topics:

• Aerodynamic design methods
• Practical design examples of new generation industrial fans
• Advancements in traditional testing of fan aerodynamics
• Experimental techniques and computational methods for the detailed analysis of fan aerodynamics
• Artificial intelligence and aerodynamic performance optimization techniques
• Improving Fan Sizing/Selection
• Unsteady phenomena and flow non-uniformities in actual fan operation
• Effects of flow characteristics and geometrical non-similarities affecting fan scaling law
• New design and analysis methods based on Artificial Intelligence or Machine Learning

Aerodynamic design methods

Classical empirical methods are the basis upon which any good fan design is developed, especially when many alternative fan configurations must be compared in the preliminary design phase. The fast solution today available for low-order RANS-CFD approaches permit to incorporate them in new conceptual design methods or in updated versions of classical aerodynamic design methods with inclusion of acoustics aspects.

Practical design examples of new generation industrial fans

New or up-to-date aerodynamic and noise effective designs suggested by/inspired to optimization algorithms or (for example) biomimicry, help fixing the present best-in-class solutions and indicating the incoming standard of fan technology.

Advancements in traditional testing of fan aerodynamics

Global aerodynamics performance testing continues to present challenges both in- and out-of-lab, whose solution permits the bridging between research and practical application, mostly important for the fan industry advancements.

Experimental techniques and computational methods for the detailed analysis of fan aerodynamics

Very highly resolved in space and time measurements acquisitions and flow visualizations techniques strongly aid understanding the details of fan internal flow and explaining the various mechanisms of losses up to a resolution level able to complement CFD that, in turn, today makes feasible: i) adding reliable unsteady RANS and, in some cases, hybrid LES/U-RANS to the consolidated RANS-CFD "workhorse", also at the industry level; ii) exploiting DNS as a complement of the very-high-fidelity URANS/LES simulations, at the research level.

Artificial intelligence and aerodynamic performance optimization techniques

Artificial intelligence is evolving well outside the initial application (still primary) in the turbomachines’ field, that is the aerodynamic performance optimization. Research is demonstrating that machine learning is opening new path of development, very attractive also for industry, for both the traditional CFD modelling approaches and experimental fluid-dynamics.

Improving Fan Sizing/Selection

Centrifugal impellers with backward/radial/forward blades arranged within spiral/box-casings, free-rotating/ducted axial fans with or without straightener/contra-vanes downstream/upstream of the rotor (or both) or with co- or contra-rotating rotors, mixed-flow and cross-flow solutions, are examples of the unique in the turbomachines’ world variety of solutions fans offer and require manufacturers/users/designers to deal with.

Unsteady phenomena and flow non-uniformities in actual fan operation

Phenomena, which appear and disappear, as well as non-uniformities (e.g., inlet flow distortions), influence the steady-state aerodynamics, which the fan design is commonly based on, worsening the expected performance and increasing the fan noise. These phenomena cannot be avoided in many instances (e.g., circumferential fans or axial fans with dissymmetric inflow characteristics) and are difficult to measure or simulate

Effects of flow characteristics and geometrical non-similarities affecting fan scaling laws

Manufacturing issues associated with the re-scaling of a specific design across the sizes of interest for fans and the associated Reynolds number variations associated with such re-scaling are utmost challenging, since scaling up and down of a fan design many times requires to account for flow regimes that move from roughly laminar to fully turbulent.

New design and analysis methods based on Artificial Intelligence or Machine Learning

Aerodynamic - and not only aerodynamic - design of fans, as well as computational and experimental analysis methods can and must be reconsidered in the light of the new results they can achieve owing to the strong support of the many techniques of artificial intelligence and machine learning now available