Technique for Adequate CFD-Modeling of the Pump With Hydro-Drive of the Low-Pressure Stage

2016 ◽  
Author(s):  
Vasilii M. Zubanov ◽  
Leonid S. Shabliy ◽  
Alexander V. Krivcov ◽  
Valeriy N. Matveev
Keyword(s):  
Rotational Speed ◽  
Cfd Simulation ◽  
Turbulence Models ◽  
Pressure Head ◽  
Low Pressure ◽  
Inlet Pressure ◽  
Cfd Modeling ◽  
Future Research ◽  
Rotor Speed ◽  
Pressure Stage

This article describes the technique for CFD-modeling of a powerful two-stage pump with the following main parameters: main rotor speed is 13,300 rpm, inlet pressure is 0.2 MPa, pressure head is more than 3,000 meters with mass flow of 250 kg/s. The main feature of investigated pump is the hydro-drive of the low-pressure stage of turbine with variable rotational speed. There are two highlights in this work in comparison with the previous ones. The first one is how to choose the rotating speed of hydro-turbine. The second one is the CFD-modeling of cavitation processes. The core part of proposed technique is the determination of rotational speed during CFD-simulation by special methodology. Another feature is the cavitation modeling to be sure that there is no cavitation in pre-pump at quite low inlet pressure and variable rotor speed. Also, recommendations about program tools (ANSYS CFX, NUMECA AutoGrid5, ANSYS ICEM CFD) are a significant part of the discussed technique, as well as modeling features (fluid domain restriction, meshing, turbulence models choosing, convergence checking, post-processing). The adequacy of CFD-model was evaluated by comparing predicted characteristics of the pump with the experimental ones derived from the test rig. The differences amounted to less than 10%. The obtained technique can be used in the future research for performance improving and efficiency increasing of pumps with hydro-drive of the low-pressure stage by CFD-tools.

scholarly journals Optimization of Powerful Two-stage Screw Centrifugal Pump

2018 ◽  
Vol 220 ◽  
pp. 03009 ◽  
Author(s):  
Oleg Baturin ◽  
Grigorii Popov ◽  
Daria Kolmakova ◽  
Vasilii Zubanov ◽  
Julia Novikova ◽  
...  
Keyword(s):  
High Pressure ◽  
Centrifugal Pump ◽  
Mathematical Optimization ◽  
Pressure Head ◽  
Low Pressure ◽  
Calculation Model ◽  
Pump Efficiency ◽  
Rotor Speed ◽  
Two Stage ◽  
Optimization Parameters

The article presents a refining method for a two-stage screw centrifugal pump by the joint usage of mathematical optimization software IOSO, meshing complex NUMECA and CFD software ANSYS CFX. The pump main parameters: high-pressure stage rotor speed was 13300 rpm; low-pressure rotor speed was 3617 rpm by gearbox; inlet total pressure was 0.4 MPa; outlet mass flow was 132.6 kg/s at the nominal mode. This article describes the process of simplifying the calculation model for the optimization. The parameters of camber lines of the low-pressure impeller, transition duct, and high-pressure impeller blades for two sections (hub and shroud) were chosen as optimization parameters. The blades of low-pressure impeller, transition duct and high-pressure impeller have changed during optimization. The optimization goal was the increase of the pump efficiency with preservation or slight increase in the pressure head. The efficiency was increased by 3%.

Experimental and theoretical analyses of two-dimensional flows upstream of broad-crested weirs

2008 ◽  
Vol 35 (9) ◽  
pp. 975-986 ◽  
Author(s):  
M. Salih Kirkgoz ◽  
M. Sami Akoz ◽  
A. Alper Oner
Keyword(s):  
Cfd Simulation ◽  
Turbulence Models ◽  
Free Surface Flows ◽  
Velocity Fields ◽  
Numerical Results ◽  
Cfd Modeling ◽  
Two Dimensional ◽  
The Finite Element Method ◽  
Image Velocimetry ◽  
Computational Fluid Dynamics Cfd

Using the particle image velocimetry (PIV) technique, the laboratory experiments are conducted to measure the velocity fields of two-dimensional turbulent free surface flows upstream of rectangular and triangular broad-crested weirs. The experimental flow cases are analyzed theoretically by a computational fluid dynamics (CFD) modeling in which the finite element method is used to solve the governing equations. In the CFD simulation, the volume of fluid (VOF) method is used to compute the free surfaces of the flows. Using the standard k–ε and standard k–ω turbulence models, the numerical results for the velocity fields and flow profiles are compared with the experimental results for validation purposes. The computed results using k–ω turbulence model on compressed mesh systems are found in good agreement with measured data. The flow cases are also analyzed theoretically using the potential flow (PF) approach, and the numerical results for the velocity fields are compared with measurements.

Development of Experimental and Numerical Methods for the Analysis of Active Clearance Control Systems

2020 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Lorenzo Mazzei ◽  
Lorenzo Tarchi ◽  
Lorenzo Cocchi ◽  
Alessio Picchi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Current Trend ◽  
Turbulence Models ◽  
Pressure Head ◽  
Test Sample ◽  
Low Pressure ◽  
Numerical Approach ◽  
Tip Clearance ◽  
Target Plate ◽  
Clearance Control

Abstract The ever increasing performance requirements of modern aero-engines necessitate the development of effective ways to improve efficiency and reduce losses. Casing temperature control is particularly critical from this point of view, since thermal expansion directly affects the blade tip clearance and thus the associated leakages. To limit the turbine tip flows, Active Clearance Control (ACC) systems have been implemented over the last decades. These systems are usually based upon impingement cooling, generated by a series of perforated manifolds enclosing the turbine casing. When dealing with aeroengine low pressure turbines, the current trend in increasing the engine by-pass ratio, so as to enhance the system propulsive efficiency, pushes the limits of ACC traditional design performance. The reduction of the pressure head at the ACC system inlet requires lower nozzle-to-target distances as well as denser impingement arrays to compensate the reduction of the jets’ Reynolds number. Literature correlations for the impingement heat transfer coefficient estimation are then out of their confidence range and also RANS numerical approaches appear not suitable for future ACC designs. In this work, methodologies for the development of accurate and reliable tools to determine the heat transfer characteristics of low pressure ACC systems are presented. More precisely, this paper describes a custom designed finite difference procedure capable of solving the inverse conduction problem on the target plate of a test sample. The methodology was successfully applied to an experimental setup for the measurement of the thermal loads on a target plate of a representative low pressure ACC impinging system. The experimental data is then used to validate a suitable numerical approach. Results show that RANS model is not able to mimic the experimental trends, while scale-resolving turbulence models provide a good reconstruction of the experimental evidences, thus allowing to obtain a correct interpretation of flow and thermal phenomena for ACC systems.

Numerical Investigation of Rotational Speed on Pump as Turbine for Microhydro Applications

2016 ◽  
Vol 833 ◽  
pp. 11-18
Author(s):  
Mohd Azlan Ismail ◽  
Al Khalid Othman ◽  
Hushairi Zen
Keyword(s):  
Flow Rate ◽  
Rural Areas ◽  
Rotational Speed ◽  
Computer Aided Design ◽  
Cfd Simulation ◽  
Simulation Analysis ◽  
Fluid Dynamic ◽  
Pressure Head ◽  
Performance Curve ◽  
Convergence Criteria

Pump as Turbine (PAT) always has been a favourable solution to generate electricity in rural areas when there is a potential microhydro site. Such systems have lower capital cost, and they are easier to maintain than commercially-available microhydro turbines. Normally, PAT is designed to run at a rated rotational speed so it can directly couple with an induction generator in order to match the synchronous speed. In an actual scenario, the PAT’s rotational speed changes and fluctuates with respect to flow rate due to the absence of a hydraulic control mechanism. It is essential to understand how the PAT behaves under different rotational speeds in order to design good microhydro systems. The aim of this study was to conduct simulation analysis of the effect of rotational speed on PAT’s performance curve over a range of flow rates. ANSYS CFX software was used as the Computational Fluid Dynamic (CFD) simulation tool in this study. Three distinct flow domains was modelled by Computer Aided Design (CAD) software and assembled as the computational fluid domains. Mesh independence analysis and convergence criteria were set to ensure the accuracy of the model. The torque generated by the impeller was collected from the simulation data and presented in the PAT performance curve. It was observed that the pressure head and torque generated increased at higher rotational speeds, thus maintaining the efficiency value. The results showed that the efficiency of the PAT was maintained around 76.5% for rotational speeds between 1350 to 1650 RPM, but the best efficiency point shifted to lower flow rate for lower rotational speed. The outcomes of this study will be useful for turbomachinery researchers, microhydro users, and project engineers for predicting the PAT performance for designing microhydro systems.

Development of Experimental and Numerical Methods for the Analysis of Active Clearance Control Systems

2020 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Lorenzo Mazzei ◽  
Lorenzo Tarchi ◽  
Lorenzo Cocchi ◽  
Alessio Picchi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Current Trend ◽  
Turbulence Models ◽  
Pressure Head ◽  
Test Sample ◽  
Low Pressure ◽  
Numerical Approach ◽  
Impingement Heat Transfer ◽  
Aero Engines ◽  
Clearance Control

Abstract To increase the performance of modern aero-engines, the control of blade tip leakages in mandatory. In the last decades, this task was performed by Active Clearance Control (ACC) systems, which manage the casing thermal deformations and the associated losses via cooling jets impinging on the casing outer surface. The current trend of increasing the engine by-pass ratio pushes the limits of ACC traditional design, since a lower pressure head is available for the generation of the jets. Therefore, denser jet patterns and lower jet-to-target distances are required to compensate the reduction of the jets' Reynolds number. Literature correlations for the estimation of impingement heat transfer are then out of their confidence range, and also RANS numerical approaches appear not to be suitable. In this work, methodologies for the development of accurate and reliable tools to determine the heat transfer characteristics of low pressure ACC systems are presented. More precisely, this paper describes a custom designed finite difference procedure capable of solving the inverse conduction problem on the target plate of a test sample. The methodology was successfully applied to an experimental setup for the measurement of the heat transfer features of a representative low pressure ACC system. The experimental data was then used to validate a suitable numerical approach. Results show that RANS is not able to mimic the experimental trends, while scale-resolving turbulence models provide a good reconstruction of the experimental evidences, thus allowing to obtain a correct interpretation of flow and thermal phenomena.

CFD modeling and validation of heat transfer inside an autoclave based on a mesh independency study

2021 ◽  
pp. 002199832097904
Author(s):  
Junhong Zhu ◽  
Tim Frerich ◽  
Axel S Herrmann
Keyword(s):  
Heat Transfer ◽  
Cfd Simulation ◽  
Stokes Equations ◽  
Numerical Study ◽  
Fluid Velocity ◽  
Turbulence Models ◽  
Cfd Modeling ◽  
Navier Stokes ◽  
Cost Calculation ◽  
Numerical Effort

Autoclave processing is the main technology used in the manufacturing of structural aerospace composite parts. To optimize the autoclave process, the thermal behavior of the part and mold can be investigated through simulations. Computational fluid dynamics (CFD) provide a significant contribution to studies on heat transfer and airflow patterns, which are key points in an optimization applied to achieve a homogeneous temperature distribution inside composite parts. The solution is produced by solving the 3 D unsteady Navier–Stokes equations. This paper describes a systematic numerical study using the CFD approach to significantly improve the modeling efficiency of the heat transfer coefficient (HTC) inside an autoclave and maintain a high level of accuracy. Considering the modeling cost, calculation time, and accuracy of the results, a reasonable hybrid mesh is used based on a mesh independency study. The level of grid independence is examined using the general Richardson extrapolation method. In addition, a more robust autoclave model is presented, which is unaffected by the inlet turbulence. Further, the inlet fluid velocity and turbulence models have been identified as sensitive influencing factors. In this study, the Spalart–Allmaras turbulence model shows the best performance compared with the standard [Formula: see text] and [Formula: see text] SST models. Finally, the results are validated with the experimental data. The mean error of the simulated temperatures in the calorimeter for the front, middle and rear positions are [Formula: see text]C, [Formula: see text]C, and [Formula: see text]C, indicating a good agreement with the experiments. This paper provides guidelines on the use of a CFD simulation to predict the heat transfer during the autoclave curing process with high accuracy and reduced numerical effort.

Influence of Hot Streak Temperature Ratio on Low Pressure Stage of a Vaneless Counter-Rotating Turbine

2007 ◽  
Author(s):  
Qingjun Zhao ◽  
Fei Tang ◽  
Huishe Wang ◽  
Jianyi Du ◽  
Xiaolu Zhao ◽  
...  
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Secondary Flow ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Temperature Ratio ◽  
High Pressure Turbine ◽  
Pressure Stage ◽  
Low Pressure Turbine ◽  
Hot Streak

In order to explore the influence of hot streak temperature ratio on low pressure stage of a Vaneless Counter-Rotating Turbine, three-dimensional multiblade row unsteady Navier-Stokes simulations have been performed. The predicted results show that hot streaks are not mixed out by the time they reach the exit of the high pressure turbine rotor. The separation of colder and hotter fluids is observed at the inlet of the low pressure turbine rotor. After making interactions with the inner-extending shock wave and outer-extending shock wave in the high pressure turbine rotor, the hotter fluid migrates towards the pressure surface of the low pressure turbine rotor, and the most of colder fluid migrates to the suction surface of the low pressure turbine rotor. The migrating characteristics of the hot streaks are predominated by the secondary flow in the low pressure turbine rotor. The effect of buoyancy on the hotter fluid is very weak in the low pressure turbine rotor. The results also indicate that the secondary flow intensifies in the low pressure turbine rotor when the hot streak temperature ratio is increased. The effects of the hot streak temperature ratio on the relative Mach number and the relative flow angle at the inlet of the low pressure turbine rotor are very remarkable. The isentropic efficiency of the Vaneless Counter-Rotating Turbine decreases as the hot streak temperature ratio is increased.

CFD Simulation of Large Dust Collection Cyclones Positioned Vertically in Staggered Downward Cascade Arrangement

2013 ◽  
Author(s):  
Eugen-Dan Cristea ◽  
Pierangelo Conti
Keyword(s):  
Cfd Simulation ◽  
Solid Phase ◽  
Phase Particle ◽  
High Mass ◽  
Cfd Modeling ◽  
Cement Kiln ◽  
Dust Collection ◽  
Dry Process ◽  
Cascade Arrangement ◽  
Simulation Results

Three dimensional, time dependent Euler-Euler simulation approach for numerical calculation of multiphase strongly swirling turbulent gas-heavy laden particulate flow in large industrial collection cyclones, positioned vertically, in staggered downward cascade arrangement has been performed. The multiphase flow was featured high mass loading. This paper specifically addresses a CFD modeling of a “suspension preheater”, typical equipment for dry process cement kiln. Big sized cyclone separator is a key component of this device. The simulation case study was developed in the frame of the commercial general-purpose code ANSYS-Fluent R13. In cyclone separators the swirling gas motion induces a centrifugal force on the solid particulate phase which is the driving force behind the separation process. The turbulence disperses the solid particulates and enhances the probability that particles are discharged, as reject. Both phenomena are related to solid phase particle size distribution (PSD) and flow pattern into the collection cyclones. The multiphase turbulence was modeled using the RSM Mixture Turbulence Model. The simulation results were validated against industrial measurements carried out on an industrial suspension preheater, in the frame of heat and mass balance of cement kiln energy audit. The numerical simulation results were found in reasonable agreement with the collected industrial measurements. This CFD simulation represents a powerful engineering tool on behalf of the cement process engineer either for new cutting-edge design or for performance verification of an existing plant.

Optimization Method of the Multistage Axial Compressors Using CFD Simulation

2021 ◽  
pp. 2141006
Author(s):  
Grigorii Popov ◽  
Igor Egorov ◽  
Evgenii Goriachkin ◽  
Oleg Baturin ◽  
Daria Kolmakova ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Optimization Problems ◽  
Search Algorithm ◽  
Pressure Ratio ◽  
Optimization Method ◽  
Cfd Modeling ◽  
Turbine Engines ◽  
Stability Margins ◽  
Axial Compressors ◽  
Cfd Models

The current level of numerical methods of gas dynamics makes it possible to optimize compressors using 3D CFD models. However, the methods and means are not sufficiently developed for their wide application. This paper describes a new method for the optimization of multistage axial compressors based on 3D CFD modeling and summarizes the experience of its application. The developed method is a complex system of interconnected components (an effective mathematical model, a parameterizer, and an optimum search algorithm). The use of the method makes it possible to improve or provide the necessary values of the main gas-dynamic parameters of the compressor by changing the shape of the blades and their relative position. The method was tested in solving optimization problems for multistage axial compressors of gas turbine engines (the number of stages from 3 to 15). As a result, an increase in efficiency, pressure ratio, and stability margins was achieved. The presented work is a summary of a long-years investigation of the research team and aims at creating a complete picture of the obtained results for the reader. A brief description of the results of industrial compresses optimization contained in the paper is given as an illustration of the effectiveness of the developed methods.

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