ATAC i system - Energimyndigheten

Project goal:
The overall objective is to investigate the feasibility of enhancing the performance for smallscale
steam turbines (less than 25 MWel) by means of aero-thermodynamic calculations and
experiments. An improved understanding of partial admission losses in low flow rate
turbomachines is one specific goal. Results may be used as design criteria for small-scale
steam turbines, possibly with advanced steam data. Another general objective is to increase
the physical understanding of partial admission losses in small flow rate turbomachines in
order to improve future design and choice of partial admission in small-scale steam turbines,
possibly with advanced steam conditions.
Preliminary date for a Licentiate exam is May/June 2003.
Methodology:
In order to meet the project goals, numerical calculations combined with experimental tests in
a cold-flow air turbine test facility at KTH are planned. Applying partial admission induces
additional losses and an attempt will be made to investigate these losses, with an emphasis on
the physical understanding of the flow mechanisms. The approach will be conduct partial
admission tests on the two-stage axial air test turbine at HPT, and one-dimensional mean-line
calculations will be performed with ALSTOM’s in-house code AXIAL. A highly loaded onestage
object will also be investigated. The calculation results will be used to determine if the
existing test object can be used for simulating partial admission and/or advanced steam
conditions for small flow rate steam turbines. If the answer to this is positive, then the
experimental measurements will be performed.
Results:
Corresponding sub-phases are presented in the time plan (see below):
Sub-phase 1.a
Small-scale steam turbines almost exclusively employ admission data below 540°C/140 bar.
The main problem with applying high-temperature steam is located to the boiler system,
where the problem consists of finding a cost-efficient and suitable material for superheaters,
piping etc. Steam parameters above 600°C exist today in large-scale generation and it is
technically feasible to incorporate these temperatures into small-scale generation although it is
economically questionable for pure Rankine cycles. However, small-scale combined cycles
with advanced steam parameters gives a more positive overall picture. A limited number of
publications regarding experimental and numerical studies about partial admission losses have
been found in the open literature, with still limited physical understanding of the flow
phenomena during partial admission. This points towards a continuation of the project with
complementing experiments.
Sub-phase 1.b
Participating in external turbine trials at DLR (Germany) and at KTH has lead to valuable
knowledge that can be used when turbine trials become current. The student is able to run the
test facility at KTH. Various courses and collaborations with national- and international
companies, research institutes and universities have broadened the knowledge about
aerothermodynamics of small-scale steam turbines.