Strategic Young Researcher Overseas Visits Programfor Accelerating Brain Circulation 2011
“Development of Young Researchers
Based on International Joint Research
on Green Energy Systems”
Progress Report

1. Name: Daisaku Sakaguchi
2. Title: Associate Professor
3. Host Institution: Von Karman Institute for Fluid Dynamics (Belgium)
4. Host Researcher: Professor Tony Arts
5. Duration: 06-March-2012 – 15-March-2013
6. Research Topic: Multidisciplinary Optimization of a Centrifugal
Compressor
7. Overview of the Results of the Collaborative Research:
A multidisciplinary optimization technique is applied to the design of a low solidity cascade
diffuser (LSD) in centrifugal compressors. An optimization code which is developed by vonKarman Institute for Fluid Dynamics (VKI) is operated by a meta-model assisted evolutionaryalgorithm. An artificial neural network (ANN) is used as the meta-model for evaluating diffuser
performance in each generation. The performance of the best shape of the LSD blade from theevolutionary algorithm is confirmed by a Reynolds Averaged Navier-Stokes Simulation (RANS).
The result of RANS analysis is stored in a database and the meta-model is re-trained by the newdatabase. Two kinds of static pressure coefficient are applied for the objective functions, one at adesign flow rate, and the other at a small low rate. The lift coefficient of the LSD blade isanalyzed at several flow rates. The slope of the lift coefficient as a function of the flow rate isapplied as a constraint of optimization. Moreover, small tip clearance of the LSD blade isapplied in order to stabilize the secondary flow effect at low flow rates. It is found that theoptimized shape of the LSD blade shows good improvement of lift coefficients in whole flow rate
ranges, and flow separation of the LSD blade is successfully suppressed by the secondary flow
effect at low flow rate conditions. The operating flow rate range is extended to the low flow rate
without deteriorating the diffuser pressure recovery at the design flow rate.
START
Level 1 Optimization loop using meta model

Design Vector

Differential
Evaluation

Geometry

CFD

Performance

Prediction

Performance

Database

Learning
Meta model (ANN)Level 2 Feedback loop

STOP

Fig.1 General layout of the VKI optimization system

Fig.2 Optimized blade of LSD

8. Deployment Plans for Future Collaborative Research:
The primary technical issue regarding energy saving in industrial plants is theimprovement of a turbomachinery, such as compressors, turbines, fans and blowers.
Numerical simulation is widely used as a turbomachinery design procedure. In mostcases, several kinds of performance parameters are required to improve simultaneously,
such as aerodynamic efficiency, compactness, a reduction in stress, improved heatresistance, and increased operating range. However, the cost of the numerical simulationis relatively high during the practical design process, and it is difficult to confirm thedesign which is combined with many parameters. The multi-disciplinary optimization
technique is one the idea that has been proposed solve the problem in the practicaldesign process. An optimization code developed by von Karman Institute for Fluid
Dynamics (VKI) is the state of the art optimization system with a meta-model assisted
evolutionary algorithm. The multi-disciplinary optimization technique with meta-modelis effective idea to reduce the simulation cost. It will be the practical design tool fordeveloping turbomachinery, including fans, blowers, compressors and turbines.
Moreover, the multi-disciplinary optimization technique is an effective tool for researchwork. Statistical results from database of the multi-disciplinary optimization techniquewill bring a significant amount of information to create new innovative designs. In thisprogram, the optimization code was successfully implemented to the CFD code
ANSYS-CFX and applied towards the development of a low solidity cascade diffuser.
Future collaborative work between VKI and Nagasaki University is development of anovel type of turbomachinery by means of the aforementioned optimization code which
is developed by this project. The collaborative research work will contribute to energy
savings for turbomachinery all over the World.

9. List of Collaborative Research Progress:
Conference Presentations
1. Daisaku Sakaguchi, Multidisciplinary Optimization Design of a Low
Solidity Cascade Diffuser (Simultaneous improvement of the aerodynamicperformance at design and small flow rate) (in Japanese), Proceedings of
the 69th annual meeting of Turbomachinery, pp.1-7, 2013
2. Daisaku Sakaguchi, Kanata Mizokoshi and Daiki Kishikawa,
Multidisciplinary Optimization of a Low Solidity Cascade Diffuser in aCentrifugal Blower, Proceeding of the 12th Asian International Conferenceon Fluid Machinery, Yogyakarta Indonesia, AICFM12-052, pp.1-9,
September, 25 – 27, 2013
3. Daisaku Sakaguchi, Takuma Eida and Kanata Mizokoshi,
Multidisciplinary Optimization Design of a Low Solidity Cascade Diffuser(Experimental Validation of the Optimized Blade) (in Japanese),
Proceedings of the 70th annual meeting of Turbomachinery, pp.1-7, 2013
4. Daisaku Sakaguchi, Multi-objective Optimization of a Low Solidity
Cascade Diffuser in Centrifugal Blowers (in Japanese), Journal ofTurbomachinery, Vol.42, No.10, pp633-641, 2014
5. Daisaku Sakaguchi, Masahiro Ishida, Hiroshi Hayami, Lasse Mueller,
Zuheyr Alsalihi and Tom Verstraete, Multipoint Multi-objective
Optimization of a Low Solidity Circular Cascade Diffuser in Centrifugal

Blowers, Proceedings of the ASME Turbo Expo 2014: Turbine TechnicalConference and Exposition, Düsseldorf, Germany GT2014-26013, pp.1-10,
June 16 – 20, 2014
6. Daisaku Sakaguchi, Min Thaw TUN, Kanata Mizokoshi and Daiki
Kishikawa, Flow Range Enhancement by Secondary Flow Effect in Low
Solidity Circular Cascade Diffusers, Journal of Thermal Science, Vol.23,
No.4, pp.391-400,2014
7. Daisaku Sakaguchi, Flow Range Enhancement of a Low Solidity
Cascade Diffuser of Centrifugal Blowers by Multi-objective Optimization,
The 5th International Conference on Science and Engineering (ICSE2014),Yangon, Myanmar, ME-13, pp.1-5, 2014
8. Min Thaw Tun, Daiki Kishikawa, Daisaku Sakaguchi, NumericalInvestigation of Centrifugal Compressor for Turbochargers with an
Optimized Ring Groove Arrangement, The 5th International Conference onScience and Engineering (ICSE 2014), Yangon, Myanmar, ME-03, pp.1-5,
2014
9. Min Thaw Tun, Daisaku Sakaguchi, Optimization and Validation ofSecondary Flow Effect for Flow Range Enhancement in a Low Solidity
Circular Cascade Diffuser, ASME-JSME-KSME Joint Fluids EngineeringConference 2015, AJK2015-FED, July 26-31, 2015, Seoul, Korea,
AJKFluids2015-02174, pp.42-51 (2015)
10. Min Thaw Tun, Diasaku Sakaguchi, Flow Range Enhancement byRecirculation Flow Type Casing Treatmentin Centrifugal Compressors ofTurbocharger, The 13th Asian International Conference on Fluid
Machinery AICFM13, Waseda, Tokyo, AICFM13-135, 	 pp.1-10, 2015
11. Daisaku Sakaguchi, Min Thaw Tun, Global Optimization of Guide
Vane in Recirculation Flow Type Casing Treatment for CentrifugalCompressors, The 6th International Conference on Science andEngineering (ICSE 2015), Yangon, Myanmar, No.79, pp.1-5, 201512. Min Thaw Tun, Daisaku Sakaguchi, PIV Measurement of the Flow
Structure in the Diffusers of a Centrifugal Blower, The 6th International
Conference on Science and Engineering (ICSE 2015), Yangon, Myanmar,
No.75, pp.1-5, 2015

13. Daisaku Sakaguchi, Min Thaw Tun, Ryusuke Numakura and Baotong
Wang, 	 Global Optimization of Recirculation Flow Type Casing Treatment
in Centrifugal Compressors of Turbocharges, The 12th International
Conference on Turbochargers and Turbocharging, London, UK,
ICTT-140,pp.1-14, 2016
14. Min Thaw Tun, Daisaku Sakaguchi, Multi-point Optimization ofRecirculation Flow Type Casing Treatment in Centrifugal Compressors,Journal of Thermal Science, Vol.25, No.3, 2016