Pumps account for 20% of global energy consumption, and energy is often the largest cost in the life cycle costs of a pump system. Critical to a good performance pump design is the ability to systematically design high-efficiency impellers with good cavitation performance, etc.
Over the years, ADT has been involved in thousands of pump designs across all different specific speeds and applications and has developed considerable fluid dynamic knowledge to design high-performance pumps systematically; here is a summary of some of the main adverse fluid phenomena that cause a drop in performances in the impeller and pump stages.
The first step in the design of any pump is to identify the required specific speed regime of the pump. This will dictate the meridional shape and the pump's general flow direction. For example, a low specific speed pump is likely to be a radial or centrifugal type, whereas a high specific speed pump is likely to be of mixed flow or axial type.
From the required specific speed, we can identify the main flow phenomena and loss mechanisms dominant in that particular range (see figure below). For example, leakage and secondary flow effects are more dominant in lower ranges, whereas profile losses and corner separation in diffusers take priority in the higher ranges. It must be noted that a phenomenon such as cavitation can affect pumps over the entire specific speed range and must be dealt with on a case basis.
From the information above, we can use design tools and 3D CFD to investigate our pump designs; what follows are a set of principal design guidelines based on the fluid dynamics considerations of reducing dominant flow losses for a given impeller/diffuser.
In this webinar, we demonstrate the optimum blade loading to control specific flow phenomena in pumps, such as secondary flow control in impellers, corner separation control in vaned diffusers or cavitation control in impellers.