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This paper aims to study the transient flow characteristics in a mixed-flow pump during the start-up period.

In this study, numerical calculation of the internal flow field in a mixed-flow pump using the sliding mesh method was carried out. The regulation of the pressure, streamline and the relative speed during the start-up period was analyzed.

The trend of the simulated head is consistent with the experimental results, and the calculated head is around 0.3 m higher than the experimental head when the rotation speed reached the stable stage, indicating that the numerical method for the start-up process simulation of the mixed-flow pump has a high accuracy. At the beginning, the velocity inside the impeller changes little along the radius direction and the flow rate increases slowly during the start-up process. As the rotation speed reached the stable stage, the flow inside the impeller became steady, the vortex reduced and transient effects disappeared gradually.

The study results have significant value for revealing the internal unsteady flow characteristics of the mixed-flow pump and providing the reference for the design optimization of the mixed-flow pump.

The purpose of this study is to explore the transient characteristics of mixed-flow pumps during startup process.

This study uses a full-flow field transient calculation method of mixed-flow pump based on a closed-loop model.

The findings show the hydraulic losses and internal flow characteristics of the piping system during the start-up process.

Large computational cost.

Improve the accuracy of current numerical simulation results in transient process of mixed-flow pump.

Simplify the setting of boundary conditions in the transient calculation.

The purpose of this paper is to experimentally and numerically study the transient hydraulic impact and overall performance during startup accelerating process of mixed-flow pump.

In this study, the impeller rotor vibration characteristics during the starting period under the action of fluid–structure interaction was investigated, which is based on the bidirectional synchronization cooperative solving method for the flow field and impeller structural response of the mixed-flow pump. Experimental transient external characteristic and the transient dimensionless head results were compared with the numerical calculation results, to validate the accuracy of numerical calculation method. Besides, the deformation and dynamic stress distribution of the blade under the stable rotating speed and accelerating condition were studied based on the bidirectional fluid–structure interaction.

The results show that the combined action of complex hydrodynamic environment and impeller centrifugal force in the startup accelerating process makes the deformation and dynamic stress of blade have the rising trend of reciprocating oscillation. At the end of acceleration, the stress and strain appear as transient peak values and the transient effect is nonignorable. The starting acceleration has a great impact on the deformation and dynamic stress of blade, and the maximum deformation near the rim of impeller outlet edge increases 5 per cent above the stable condition. The maximum stress value increases by about 68.7 per cent more than the steady-state condition at the impeller outlet edge near the hub. The quick change of rotating speed makes the vibration problem around the blade tip area more serious, and then it takes the excessive stress concentration and destruction at the blade root.

This study provides basis and reference for the safety operation of pumps during starting period

There are three pumping stations in the first stage of Eastern Route S-to-N Water Diversion Project in China, where the mixed-flow pumps with guide vanes are installed, consisting of Baoying, Hongze and the No. 2 Suining pumping stations. By using flow rate coefficient and head coefficient as expression, firstly the hydraulic performances of the hydro models used are analyzed. Secondly the structural features and system performances are compared. And finally the measurement results in site are comprehensively evaluated. The results show that the pump models both introduced abroad and developed at home and the pumping system types adopted in the three pumping stations have been confirmed satisfying the requirements of operational conditions and high efficiency, stable and safety operation in all working conditions can be ensured.

This paper aims to investigate the effect of three-dimensional (3D) inlet guide vanes (IGVs) on performance of a centrifugal pump.

A design method for 3D IGVs is proposed based on the controllable velocity moment, which is determined by a fourth-order dimensionless function. Numerical simulation of the centrifugal pump with IGVs is carried out by solving the Reynolds-averaged Navier–Stokes equations. The method of frozen rotor is applied to couple the stationary and rotational domain.

The efficiency of pump with 3D IGVs is higher than that with 2D IGVs for most prewhirl angles, which validate the advancement of 3D IGVs on prewhirl regulation. The effect of prewhirl regulation at small flow rate is more significant than that at large flow rate.

A prediction model of velocity moment based on the Oseen vortex is proposed to describe the flow pattern downstream the IGVs.

The systems aspects of an uninhabited tactical aircraft (UTA) preliminary design are detailed. The study, performed at the post‐graduate level at Cranfield University, looks to investigate the feasibility of unmanned combat aircraft in a number of roles to reduce the risk to pilots and reduce life cycle costs (LCC). The scope of the work includes stealth, vulnerability, mission effectiveness, avionics, landing gear, secondary power, fuel systems, propulsion, performance and cost. The unusual depth to which the design work progressed enables insights to be gained that far exceed those available at the conceptual design phase. A Northrop Grumman concept of near‐identical configuration has subsequently reached the public domain.

Produced by CFM International which is a joint company of SNECMA and General Electric (USA), the CFM 56‐2 entered commercial airline service earlier this year in the re‐engined DC‐8. In addition, the first KC 135 tanker aircraft for the USAF to be re‐equipped with these powerplants has flown recently. Certification of a lower‐thrust version, the CFM 56‐3, is scheduled for September, 1983. This has been chosen for the Boeing 737‐300 which is due to fly in 1984, and other applications are envisaged in the future.

THE aerodynamic sessions of this year's Annual Meeting were not quite as dramatic as in some preceding years. But how can such sessions remain always at the highest pitch? Aeroplane designers have broken through the sonic barrier and aerodynamicists now understand far better compressibility effects and supersonics. One cannot expect every year a startling announcement of the kind that von Kármán used to make, that the drag coefficient would actually drop in supersonic flight, or that camber contributes nothing to lift at the highest speeds. This intellectual calm is only temporary. Rocket flight at a hundred miles altitude where molecules become individuals will bring tine new problems. So will the design of artifificial satellites. But for the time being, research men and engineers must present papers that dig deep but do not strike out into new territory. Also it is barely possible that there is another reason for the less exciting character of the aerodynamic papers—the word ‘Restricted’. For example, in one session it appeared that the fuel consumption of a jet‐propelled helicopter is still restricted information. To mark things ‘Re‐stricted’ or ‘Confidential’ can become a tiresome habit. However, there was no lack of the striking in other directions. What, for example, could be more intriguing than a session entitled Human Engineering in Aviation? Aeronautics is not all a matter of physics, mathematics, design and innumerable gadgets. It is more than fitting that psychologists, teachers, physicians should play their part and make the life of the pilot an easier one. Of course, the engineers do occasionally develop ‘gadgets’ that help the pilot, as witness the remarkable Sperry Zero Reader (discussed in the Instruments Session), and Air‐Borne Radar (Air Transport Session) that seems to be coming into its own.

This paper aims to develop a dynamic performance model of three-shaft gas turbine for electricity generation and to study a multi-loop control strategy of three-shaft gas turbine for electricity generation.

In this paper, the dynamic performance model of the three-shaft gas turbine is established and developed. A novel approach, variable partial differential coefficient deviation linearization method is used to simulate the dynamic performance of the three-shaft gas turbine. Single-loop control system, feed-forward feedback control system and cascade system are assessed to control the engine during transient operation.

A novel approach, variable partial differential coefficient deviation linearization method is used to simulate the dynamic performance of the three-shaft gas turbine. According to the results shown, the cascade control system is most satisfactory due to its fastest response and the best stability and robustness.

The method of variable partial linearization is adopted to make the dynamic simulation of the model achieve higher precision, better steady state and less computation time. This paper provides a theoretical study for the multi-loop control system of a marine three-shaft gas turbine.

The purpose of this paper is to focus on the structural integrity of the rainwater propeller pumps installed in the municipal wastewater treatment plant (WTP).

A numerical analysis is performed to determine the maximum shear stress on the fasten bolts. The rainwater propeller pump is examined in operation at normal conditions and when one blade is progressively blocked.

The failure mechanism of the rainwater pump impeller is determined.

The fibbers and wastes are discharged together with rainwater during storms with these types of pumps to avoid the flood of the WTP. Several catastrophic events have occurred in service due to the fibbers clog the gap between the impeller blades and the pump casing. The clogging process is partially understood so actual technical solutions deal with effects rather the main causes.

The operation time of all seven rainwater pumps installed in Timisoara’s WTP is investigated. Climate changes in Banat region and new waste properties found in the wastewater require appropriate technical solutions. A technical solution is proposed based on these investigations to extend the operation time and to diminish the operation and maintenance costs.

These large pumps are installed in the urban sewage centralised system implemented in the most cities. The access to the sewerage network is a requirement of any community, regardless of the social status.

The fracture surfaces of both fastening bolts of the rainwater pump impellers produced in service are examined. As a result, it has been identified that the catastrophic events are due to the brittle fracture of both fasten bolts between the impeller blades and the pump hub, respectively. The catastrophic events of the rainwater propeller pumps are directly correlated to the clog level of the impeller. The numerical simulation is performed to determine the maximum shear stress on the fasten bolts. The case with pump operating at normal conditions is performed identifying its vulnerabilities to clog conditions. Next, one impeller blade is progressively blocked considering three time stop scenarios associated with different clog levels. Conclusively, the operating time of the rainwater pump up to the catastrophic failure is correlated to the clog level of the impeller.