Effects of the Rates on the Performance and Pressure Pulsations of a High-Speed Pump with Straight Blade

Along with the crucial requirement for efficiency improvement in the cutting-edge petrochemical technology, the evaluation of the dynamic performance characteristics of high-speed pump is becoming increasingly important. It has become a main topic in the research of high-speed pump to minimize the pressure pulsation induced by the fluid in the pump body, so as to reduce the mechanical vibration. Although the research on the transient flow characteristic and pressure fluctuation of a high-speed pump with straight blades is of great significance, it has been seldom explored. In this work, the flow instability of a 16 straight-blade high-speed centrifugal pump is studied numerically at a rotational speed of 8500 rpm and flow rate of 3 m3/h. Results show that with the influence of rotor-stator interaction, time-domain pressure signals at the tongue show double peak characteristic, whereas a single peak characteristic exists at the diffuser wall. The pressure fluctuation near the tongue is reduced to approximately half of that at the volute wall by the water ring effect accompanied with the high-pressure factor. At the tongue region, the amplitude of the blade passing frequency is reduced by the unsteady flow, whereas the harmonic wave was increased at 2–4 times of the blade passing frequency.

Investigating of Flow Field and Power Performance on a Straight-blade Vertical Axis Wind Turbine with CFD Simulation

Forecasting the power performance and flow field of straight-blade vertical axis wind turbine (VAWT) and paying attention to the dynamic stall can enhance more adaptability to high turbulence and complicated wind conditions in cities environment. According to the blade element-momentum theory, the force of blade is analyzed in one period of revolution based on the structural characteristics of straight blade airfoil. The power performance of VAWT obtained by computational fluid dynamics (CFD) simulation is compared with experiment to estimate the accuracy about the numerical simulation results. As a result, the trend of average value of simulation Cpower is entirely consistent with the value of experiment data, and the extreme value of average Cpower of VAWT is 0.225 for tip speed ration (TSR) λ=2.19 when the freestream velocity is 8 m/s. The flow separation around the blade surface also gradually changes with the azimuth angle increasing, and the maximum pressure difference on the blade surface appears in the upstream. In the case of high leaf tip velocity, the synthetic velocity is much larger than the incoming wind velocity, and the angle of synthetic velocity increases slightly with the increase of blade tangential velocity. Thus, the angles of attack are very close in two TSRs λ=2.19 and 2.58. The research provides a computational model and theoretical basis for predicting wind turbine flow field to improve wind turbine power performance.

DESIGN AND MODELING OF STRAIGHT-BLADE VERTICAL AXIS WIND TURBINE IN PAKISTAN

Pakistan is one of those countries which has large potential of energy harvest from renewable energy sources and specially from wind. With the surge of global warming, the world is moving towards cleaner and viable sources of energy. Horizontal Axis Wind Turbines (HAWT) currently dominates the most of the wind power farm markets in the world but Vertical Axis Wind Turbines (VAWT) are also capable of harvesting large amounts of energy with benefits over the HAWTS. VAWTS do not need a control system to be pointed in the direction of wind because with its blade in radial arrangement, wind from any direction is useful. In this report, a Straight-Blade VAWT is designed for low speeds and its performance parameters are also identified for which the improvement of the VAWT will be obtained. Self-starting ability of VAWT is also analyzed and stress and vibration analysis will be investigated in ANSYS Fluent.

Design And Control System of Automatic Control System of Coal Flow on Belt Conveyor Installation

In a power plant unit whose main fuel is coal, there is generally use a belt conveyor installation. This conveyor belt serves to supply coal from the crusher unit to the combustion chamber of the power generation unit. In this study, we discuss a case where the installation of a belt conveyor which was initially only one line was then made a new branch that supplies coal to other power generating units. Equitable capacity distribution and continuity of coal distribution are the main focus of this study. Therefore, a design of automatic control system of coal flow divider on belt conveyor installation was designed. The working principle of this coal flow splitting system is to control the movement of the straight blade plough that directs the flow of coal to each unit at the certain time and continuously. Straight blade plough in the form of steel metal plate with a thickness of about 10 millimeters in which one end is connected to the end of the pneumatic cylinder. Automatic control system of coal flow divider in belt conveyor installation designed using CX-Programmer and CX-Designer applications. CX-Programmer serves to create automatic control logic concepts. While the CX-designer functions to create a Human Machine Interface (HMI), making it easier for operators to control the course of the coal supply process. The results of this study are in the form of control logic lines that can be applied to Programmable Logic Control (PLC) device and Human Machine Interface (HMI) equipment.

Investigation of ultrasonic-assisted CNC cutting of honeycomb cores

As compared to traditional milling, ultrasonic-assisted cutting of honeycomb core materials has the advantages of small cutting force and superior surface quality. Currently, ultrasonic straight blade V-shaped machining is one of the most efficient roughing processes. The requirement of a processing path to be post-processed based on the processing characteristics of the straight blade cutter is one of the key issues faced while meeting the technological requirements of CNC machine tools for V-shaped machining. A post-processing method of NC code for V-shaped machining of straight blade cutter is proposed in this article. Initially, the V-shaped rough machining process planning is done, followed by the usage of Unigraphics (UG) to output the initial CNC code. Next, the CNC code is executed through the three key technologies of the second arrangement of cutter locations. Later, research is done on information planning of lifting and lowering cutter, along with research on planning of chip breaking toolpath. Eventually, the simulation cutting experiment is carried out through VERICUT. The results demonstrate that the post-processing method can meet the processing requirements.

Wake characteristics of a freely rotating bioinspired swept rotor blade

Rotor blades can be found in many engineering applications, mainly associated with converting energy from fluids to work (or electricity). Rotor blade geometry is a key factor in the mechanical efficiency of the energy conversion process. For example, wind turbines' performance directly depends on the blade geometry and the wake flow formed behind them. We suggest to use a bioinspired blade based on the common swift wing. Common swift ( Apus apus ) is known to be a long-distance flyer, able to stay aloft for long periods of time by maintaining high lift and low drag. We study the near-wake flow characteristics of a freely rotating rotor with swept blades and its aerodynamic loads. These are compared with a straight-bladed rotor. The experiments were conducted in a water flume using particle image velocimetry (PIV) technique. Both blades were studied for four different flow speeds with freestream Reynolds numbers ranging from 23 000 to 41 000. Our results show that the near wake developed behind the swept-back blade was significantly different from the straight blade configuration. The near wake developed behind the swept-back blade exhibited relatively lower momentum loss and suppressed turbulent activity (mixing and production) compared with the straight blade. Comparing the aerodynamic characteristics, though the swept-back blade generated relatively less lift than the straight blade, the drag was relatively low. Thus, the swept-back blade produced two to three times higher lift-to-drag ratio than the straight blade. Based on these observations, we suggest that, with improved design optimizations, using the swept-back configuration in rotor blades (specifically used in wind turbines) can improve mechanical efficiency and reduce the energy loss during the conversion process.