Spatial Harmonic Decomposition as a tool for unsteady flow phenomena analysis

27th IAHR Symposium on Hydraulic Machinery and Systems

Duparchy, A.^1 ; Guillozet, J.^1 ; De Colombel, T.^1 ; Bornard, L.^1

Alstom Hydro France, Av. Léon Blum 8.2., Grenoble Cedex 9

38041, France^1

关键词: Dynamic pressure fields;    Linearly independents;    Mathematical approach;    Mathematical descriptions;    Model test measurements;    Renewable electricity;    Renewable energy technologies;    Unsteady flow phenomenon;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/22/3/032016/pdf
DOI  :  10.1088/1755-1315/22/3/032016

来源: IOP

【 摘 要 】

Hydropower is already the largest single renewable electricity source today but its further development will face new deployment constraints such as large-scale projects in emerging economies and the growth of intermittent renewable energy technologies. The potential role of hydropower as a grid stabilizer leads to operating hydro power plants in «off-design» zones. As a result, new methods of analyzing associated unsteady phenomena are needed to improve the design of hydraulic turbines. The key idea of the development is to compute a spatial description of a phenomenon by using a combination from several sensor signals. The spatial harmonic decomposition (SHD) extends the concept of so-called synchronous and asynchronous pulsations by projecting sensor signals on a linearly independent set of a modal scheme. This mathematical approach is very generic as it can be applied on any linear distribution of a scalar quantity defined on a closed curve. After a mathematical description of SHD, this paper will discuss the impact of instrumentation and provide tools to understand SHD signals. Then, as an example of a practical application, SHD is applied on a model test measurement in order to capture and describe dynamic pressure fields. Particularly, the spatial description of the phenomena provides new tools to separate the part of pressure fluctuations that contribute to output power instability or mechanical stresses. The study of the machine stability in partial load operating range in turbine mode or the comparison between the gap pressure field and radial thrust behavior during turbine brake operation are both relevant illustrations of SHD contribution.