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Ebara Engineering Review No.197

Turbomachinery Blade Optimization by 3-Dimensional Inverse Design Method - 3rd Report, Application to Aerodynamic Design and New Theory -

by Akira GOTO, Hiroyoshi WATANABE, Hideomi HARADA, & Mehrdad ZANGENEH

The actual design of centrifugal compressor impeller blades and axial-flow steam turbine rotor blades by an inverse design method is discussed. An optimal flow field is assumed as the input value and the blade shape for realizing this is determined by numerical calculation. Numerical calculation and test results indicate that stage efficiency had been improved for both types of blades. In case of the compressor, the secondary flow in the impeller was suppressed to make the flow at the impeller exit uniform. In case of the steam turbine, the stacking at the nozzle was optimized by controlling the interaction of the horse shoe vortex occurring around the blade roots. The inverse design method for 3-Dimensional viscous transonic flow is introduced as a next generation inverse design. An example of using this method for the redesign of a transonic axial-flow fan is introduced as well.

Keywords
Inverse design, Computational fluid dynamics, Optimization, Blade design, Turbomachinery, Aerodynamic design, Compressors, Turbines

Evaluation on Rotordynamic Stability by a Rotordynamics Test Stand equipped with Active Magnetic Bearings

by Masato EGUCHI, & Kazuo TAKEI

A rotordynamics test stand, equipped with an active magnetic bearing unit, was developed for measuring fluid reaction forces generating on annular pressure seals and bearings of pumps. The active magnetic bearing unit enables control of eccentricity and the whirl radius of rotor towards the center of a test piece. This advantageous characteristic made it possible to make precise estimations on fluid reaction forces under various parameters. The following introduces examples of estimations on fluid dynamics and seal dynamics around impellers under fault conditions, a feat considered difficult to achieve by rotordynamic analysis. The importance of studying properties under different temperature, pressure, and eccentricity versus turbomachinery design is discussed as well.

Keywords
Rotordynamics, Fluid reaction force, Stability, Magnetic bearing, Impeller, Annular pressure seal, Slide bearing

Vibrations at Pump Stations and Countermeasures

by Toshitsugu SASE, Hideki KANNO, Shiketsu KAKU, Michiaki MATSUDA, Michiko ISHIDA & Hidenobu OKAMOTO

A study was conducted on the prediction and control of vibration and noise at pump stations. A coupled analysis on structural elements and the water flow was applied. Vibration problems at a large-scale drainage pump station were solved by implementing trip wires on impeller blades. This achieved reductions in pressure fluctuation and changes in natural frequency. The FEM (Finite Element Method) was used for analyzing and establishing vibration/noise reduction for a seawater intake pump station. The FEM model constituted the basic structural elements (pump base, wall, ground and poles) and the pumps. Soft rubber was used for the vibration and noise control of reduction gear operating frequency, as well as high frequency vibration and noise.

Keywords
Vibration, Noise, Finite element method, Excitation force, Natural frequency, Drainage pump station, Axial flow movable vane pump, Separation, Tripping wire, Speed reducer

Dynamic Characteristics of a Drainage Pump Flap Valve

by Hiroyuki MUSHA, Tosio MIWA, Hiromu SUGIYAMA, Kazuhide MIZOBATA, Yuji SASAKI, & Kiyonobu OHTANI

A study was made on dynamic characteristics of a drainage pump flap valve in an attempt to clarify the closing of the valve during emergency shutdowns of the pump. A 100 mm diameter test apparatus was used to measure changes in the internal pressure of the valve during valve closure, the impact acceleration, and the valve opening angle. Methods of reducing and suppressing impact forces were studied. Test results revealed that impact acceleration during valve closure increased in proportion to flow velocity damping, that this acceleration force could be suppressed and reduced by increasing the mass of the valve and implementing a valve seat angle. It was also found that the water column separation, generated in the proximity of the valve, could be suppressed by using an air inlet pipe.

Keywords
Flap valve, Water column separation, Impact acceleration, Pipe flow, Drainage, Testing Facility, Pump station

Radio Monitoring System for Manhole Pump

by Etsuko SAKURAI, Isamu KAMATA, Masao SHIMADA, Tomoya TAKEUCHI, Shinji OSUMI, & Toshihiko KASAHARA

A radio monitoring system has been developed for the monitoring of manhole pumps. This system is capable of monitoring a maximum of 31 manhole pump stations through one public phone connection, thus achieving a great reduction in telecommunication cost. This was made possible by exchanging some parts of an existing EBARA monitoring system (EMMD). The following outlines this system and introduces actual feedback.

Keywords
Manhole pump, Radio monitoring system, Operation and maintenance, Cost reduction, Telephone charge, NTT connection station, EMMD-NT connection device, EMMD-SS data monitoring device, Radio apparatus, Specified low power radio

Development of Inclined Submersible Motor-Pump

by Takanobu OBA, Akira SASAKI, Michio TAKASHIMA, Hitoshi SAKAMOTO, Nitichai SINDHAVAJIVA

EBARA's Inclined Submersible Motor-Pump series, capable of pumping up water from shallow rivers during droughts, is now being used for irrigation in Laos and Vietnam. This pump is ideal for use in areas with great water level fluctuations and uneven subsidence and rise of embankments. Its maintenance is facilitated and no consolidated foundation is necessary. The following outlines this series and introduces some operational data.

Keywords
Water-level fluctuation, Uneven subsidence and rise, Submersible motor pump, Inclined shaft turbine pump, Bank, Rail, Wheel, Quick conecting flange

Municipal Waste Fluidized-bed Gasification Melting Furnace with Power Recovery Turbine - First Domestic Use by Sakata Refuse Disposal Union -

by Kiyoshi SAITO, Iku SATO, Arihiro OKAMOTO, Takanobu MIYAKI, Kenichiro AKITA,Takahiro KAWACHI, Yuichi NAKAMURA, & Eiji ISHIKAWA

Japan's first municipal waste, fluidized-bed, gasification-melting furnace system, equipped with a power recovery steam turbine, has started operation at Sakata City, Japan. The dioxin concentration in the exhaust gas of this system is being controlled to be below the allowable standard [0.1 ng-TEQ/m3(NTP)] and the produced slag is effectively encapsulated and used as pavement material (inter-locking blocks). The exhaust gas from the furnace is used for driving a power recovery turbine (max. output 1990 kW) and excess electricity produced is being sold to the local electricity company.

Keywords
Fluidized-bed, Gasification furnace, Melting furnace, Boiler, Steam turbine generator, Slag, Dioxins, Pulverizer, Catalytic reacting tower

Photovoltaic Power Generation System - Integrated with Ebara Solar Inc.'s Photovoltaic Modules -

by Masaru KOJIMA, Kenichi KUROKAWA, Taiji YAMAMOTO, Kentarou FUJITA, Mitsuhiko SHIRAKASHI & Naoki ISHIKAWA

EBARA's Photovoltaic Power Generation System, integrated with EBARA Solar Inc.'s photovoltaic modules, has been released into the market. Lightweight, resin covered photovoltaic modules feature a solar louver function enabled by a drive unit equipped directly on the atrium. Glass covered photovoltaic modules feature a design which integrates them with the outer wall of buildings. There is also a hybrid system with a capability to store power co-generated by the photovoltaic and small-scale wind turbine power generators. This system provides a stable power supply. The following outlines this system and introduces data from actual commercial operations.

Keywords
Photovoltaic power system, Drive unit of photovoltaic module, Resin covered photovoltaic module, Glass covered photovoltaic module, Single crystalline silicon solar cell, Hybrid system, System interconnection inverter, Small wind turbine generator, Display board