In this paper, axial thrust problems of multistage pumps are presented. The entire investigation has been focused on the pump design concept having all impellers in series (facing in one direction) and is valid for barrel casing type as well as for segmental type. The major part of the investigation has been experimental on one stage testing arrangement, using also Laser Doppler Anemometry (LDA) for determination of fluid rotation in the impeller side chamber. Numerical flow analysis (NFA) has been applied for some flow variants in order to verify whether a numerical approach could simulate the test results. The phenomenon of fluid rotation in side chambers and its effect on impeller hydraulic axial thrust have been determined for different leakage flow regimes. The influence of increased wear ring radial clearance on axial thrust has been analyzed together with the solutions for pump hydraulic axial thrust reduction.

The paper concerns an investigation of the characteristics of one stage radial centrifugal turbines (RCT). A test turbine with parallel side walls and specific speed nqT ≈ 25 was designed as a special case due to simplicity of the execution. The tests were carried out with air, whrerby the flow, due to small Mach–number, could be considered as incompressible. For that purpose, a special test stand was built, which enables the measurement of required values. The effects of changing some cascade parameters of stator and rotor were investigated. The results of the measurements are presented in shell diagrams in dimensionless form and compared to each other. Paralell to the measurements some calculations of fluid flow in particular parts of RCT were carried out by using TASCflow package. On the basis of experimental and theoretical research an information of optimum RCT design has been obtained from the efficiency and pressure number point of view. The generalised shape of the shell diagrams shows the favourable characteristics particular to RCT, which opens new perspectives on the use of this type of turbine. There are numerous of possibilities of energy recuperation, to use the RCT, especially in a processing industry, which become due to ecological and also economical aspect very interessting.

Forschung im Ingenieurwesen 65 (z999) 13-19 9 Springer-Vertag z999 einer einstufigen Radialturbine Zusammenfassung Gebaut wurde eine einstufige, radiale O und zentrifugale Versuchsturbine. Die Messungen der v m2/s Energiekennlinien wurden mit Luft durchgefiihrt fiir drei p kg/m 3 verschiedene Leitschaufelzahlen, sowie fiir drei Laufrad-~ profile. Die Meflergebnisse werden in dimensionslosen cp -Muscheldiagrammen dargesteltt. Die gemessenen Werte ~ sind in einem Cordier Diagramm eingetragen, um einen c,) Rad -1 Vergleich mit anderen Str6mungsmaschinen vorzunehmen. Anhand der Verlustanalyse wird versucht, den Ein-Indizes fluff der Corioliskraft n~iher zu bestimmen. L Experimental investigation of one-stage r th radial turbine W Abstract An one-stage radial centrifugal turbine was de-0 signed, Measurements of energy characteristics for dif-O0 ferent number of gude vanes as well as different turbine rotor-types were performed with air. The results of the 1 2 measurements are presented dimensionless in the shell-

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The vibrations of hydraulic pump and connected pipeline system are very problematic and often hardly soluble. The high pressure pulsations of hydraulic pump with the double suction inlet are investigated. For that reason the static pressure and accelerations are measured. The numerical simulations are carried out in order to correlate computed data with experimental ones and assess the main source of vibrations. Consequently the design optimization of the inner hydraulic part of pump is done for further experimental measurements with the variable pump discharge and speed. Several optimizations were considered-guide ribs in pump suction, an optimized diffuser and modified shaft bearings. The influence of optimized designs on the pump vibrations is discussed.