scholarly journals A Methodology for Modelling of Steady State Flow in Pelton Turbine Injectors

2019 ◽  
Vol 15 (2) ◽  
pp. 246-255
Author(s):  
Tri Ratna Bajracharya ◽  
Rajendra Shrestha ◽  
Ashesh Babu Timilsina
Keyword(s):  
Velocity Profile ◽  
High Speed ◽  
Three Dimensional ◽  
Maximum Error ◽  
Cfd Modelling ◽  
Pelton Turbine ◽  
Short Period ◽  
Computational Fluid Dynamics Cfd ◽  
Jet Velocity ◽  
Nozzle Opening

 Pelton turbine is a high head-impulse type turbine. The high-speed jet strikes the symmetrical semi ellipsoidal buckets, thus transferring the momentum within short period of time, impulse. The conversion of potential energy of water to kinetic energy in the form of jet is done by a nozzle with internally fitted spear or needle, the assembly in known as injector. The jet quality includes but is not limited to jet velocity, velocity distribution ‘velocity profile’, core location etc. In this study, the modeling of flow in Pelton turbine injector is done by commercial Computational Fluid Dynamics (CFD) solver on a three-dimensional flow domain. The results obtained from CFD modelling are then compared against the experimental observations and previously published literatures. The jet streamline, jet velocity profile and jet core location are then studied. As observed experimentally, the mean jet diameter reduces as the nozzle opening decreases. In addition, like the experimental observations, the jet first contracts and then expands. The diameter of the contraction is then normalized with nozzle exit diameter and is plotted for both experimental observations as well as the results of the numerical simulation. The maximum error between experimental and numerical analysis of jet contraction is 20%. The jet core is located at region axially ahead of needle tip.

scholarly journals Application of a three-dimensional viscous transonic inverse method to NASA rotor 67

2002 ◽  
Vol 216 (3) ◽  
pp. 243-255 ◽  
Author(s):  
W. T. Tiow ◽  
M Zangeneh
Keyword(s):  
High Speed ◽  
Inverse Method ◽  
Static Pressure ◽  
Three Dimensional ◽  
Test Case ◽  
Shock Formation ◽  
Pressure Loading ◽  
Design Computation ◽  
Computational Fluid Dynamics Cfd ◽  
Blade Geometry

The development and application of a three-dimensional inverse methodology in which the blade geometry is computed on the basis of the specification of static pressure loading distribution is presented. The methodology is based on the intensive use of computational fluid dynamics (CFD) to account for three-dimensional subsonic and transonic viscous flows. In the design computation, the necessary blade changes are determined directly by the discrepancies between the target and initial values, and the calculation converges to give the final blade geometry and the corresponding steady state flow solution. The application of the method is explored using a transonic test case, NASA rotor 67. Based on observations, it is conclusive that the shock formation and its intensity in such a high-speed turbomachinery flow are well defined on the loading distributions. Pressure loading is therefore as effective a design parameter as conventional inverse design quantities such as static pressure. Hence, from an understanding of the dynamics of the flow in the fan in relation to its pressure loading distributions, simple guidelines can be developed for the inverse method in order to weaken the shock formation. A qualitative improvement in performance is achieved in the redesigned fan. The final flowfield result is confirmed by a well-established commercial CFD package.

Experimental and Numerical Study of Hydrodynamic Cavitation of Orifice Plates with Multiple Triangular Holes

2012 ◽  
Vol 256-259 ◽  
pp. 2519-2522 ◽  
Author(s):  
Zhi Yong Dong ◽  
Qi Qi Chen ◽  
Yong Gang Yang ◽  
Bin Shi
Keyword(s):  
Velocity Profile ◽  
High Speed ◽  
Numerical Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Orifice Plate ◽  
Hydrodynamic Cavitation ◽  
High Speed Photography ◽  
Hydraulic Characteristics ◽  
Image Velocimetry

Hydraulic characteristics of orifice plates with multiple triangular holes in hydrodynamic cavitation reactor were experimentally investigated by use of three dimensional particle image velocimetry (PIV), high speed photography, electronic multi-pressure scanivalve and pressure data acquisition system, and numerically simulated by CFD software Flow 3D in this paper. Effects of number, arrangement and ratio of holes on hydraulic characteristics of the orifice plates were considered. Effects of arrangement and ratio of holes and flow velocity ahead of plate on cavitation number and velocity profile were compared. Distribution of turbulent kinetic energy and similarity of velocity profile were analyzed. And characteristics of cavitating flow downstream of the orifice plate were photographically observed by high speed camera. Also, a comparison with flow characteristics of orifice plate with hybrid holes (circle, square and triangle) was made.

Study on the Field Dynamics of the Seal Cavity Flow Field for High Parameters Bellows Mechanical Seal

2011 ◽  
Vol 99-100 ◽  
pp. 1287-1292
Author(s):  
Wei An Meng ◽  
Mutellip Ahmat ◽  
Nijat Yusup ◽  
Asiye Shavkat
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Three Dimensional ◽  
Cavity Flow ◽  
Mechanical Seal ◽  
Sealing Performance ◽  
Numerical Simulation Methods ◽  
Field Velocity ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

Based on the computational fluid dynamics (CFD) theory and numerical simulation methods, the seal cavity flow field for the bellows mechanical seal under such the high temperature, high pressure, high-speed as complex working conditions was numerically simulated, and the temperature field, velocity field, pressure field, turbulent kinetic energy and the flow field vorticity distribution of the medium of the seal cavity were obtained, the three-dimensional fluid flow in the seal cavity, the heat transfer characteristics and the impact on the sealing performance were analyzed in this researching.

3D Numerical Simulation of the Airflow in a Pneumatic Splicer

2011 ◽  
Vol 130-134 ◽  
pp. 2345-2348
Author(s):  
Xiao Xing ◽  
Guo Ming Ye
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Air Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Swirling Flows ◽  
Computational Results ◽  
Cfd Model ◽  
3D Numerical Simulation ◽  
Computational Fluid Dynamics Cfd

To investigate the effect of air flow in an pneumatic splicer on splicing performance, a computational fluid dynamics (CFD) model has been developed to simulate the air flow characteristics in an splicing chamber. Three-dimensional numerical simulation is conducted and standard K-ε turbulence model is used. Velocity distributions in the chamber are presented and analyzed. The computational results show that the velocities in the chamber are transonic. The air flows in the chamber are two swirling flows with opposite directions. This work also shows that CFD technique can provide a better understanding of the behavior of the high speed air flow in the air splicing chamber.

scholarly journals Influence of Posture Change on Train Running Safety under Crosswind

2021 ◽  
Vol 11 (13) ◽  
pp. 6067
Author(s):  
Jian Yan ◽  
Tefang Chen ◽  
Shu Cheng ◽  
E Deng ◽  
Weichao Yang ◽  
...  
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Aerodynamic Load ◽  
Lateral Direction ◽  
Running Safety ◽  
Derailment Coefficient ◽  
Safety Risks ◽  
High Speed Trains ◽  
Computational Fluid Dynamics Cfd

High-speed trains serving in a crosswind region are bearing more significant safety risks. Based on the three-dimensional (3D) Unsteady Reynolds-Averaged Navier–Stokes (URANS) turbulence model, a Computational Fluid Dynamics (CFD) computational work was conducted in the present study to predict the transient aerodynamic load of the train. The transient aerodynamic load was then employed as the input of the dynamic system to perform a dynamic analysis of running safety. Noticeable changes in the aerodynamic coefficients were found when the train entered and left the crosswind region due to the dramatic change in flow patterns. The original posture also provided significant changes to the train’s aerodynamic responses. A slightly larger maximum derailment coefficient was found on the first bogie of the leading car with a preset posture. There were obvious differences in the displacement characteristics of the three cars in the lateral direction and the rolling rotation, and the magnitude of the posture changes decreased from the leading car to the trailing car. The train with the consideration of posture was proven to withstand weaker crosswinds.

scholarly journals Drag Reduction by Application of Aerodynamic Devices in a Race Car

2020 ◽  
Author(s):  
Devang S. Nath ◽  
Prashant Chandra Pujari ◽  
Amit Jain ◽  
Vikas Rastogi
Keyword(s):  
Drag Reduction ◽  
Drag Force ◽  
High Speed ◽  
Lift Coefficient ◽  
Three Dimensional ◽  
Fuel Prices ◽  
Race Car ◽  
High Speeds ◽  
Maximum Drag Reduction ◽  
Computational Fluid Dynamics Cfd

Abstract In this era of fast-depleting natural resources, the hike in fuel prices is ever-growing. With stringent norms over environmental policies, the automotive manufacturers are on a voyage to produce efficient vehicles with lower emissions. High-speed cars are at a stake to provide uncompromised performance but having strict rules over emissions drives the companies to approach through a different route to keep the demands of performance intact. One of the most sought-after ways is to improve the aerodynamics of the vehicles. Drag force is one of the major setbacks when it comes to achieving high speeds when the vehicle is in motion. This research aims to examine the effects of different add on devices on the vehicle to reduce drag and make the vehicle aerodynamically streamlined. A more streamlined vehicle will be able to achieve high speeds and consequently, the fuel economy is also improved. The three-dimensional car model is developed in SOLIDWORKS v17. Computational Fluid Dynamics (CFD) is performed to understand the effects of these add on devices. CFD is carried out in the ANSYSTM 17.0 Fluent module. Drag Coefficient (CD), Lift Coefficient (CL), Drag Force and Lift Force are calculated and compared in different cases. The result of the simulations were analyzed and it was observed that different devices posed several different functionalities, but maximum drag reduction was found in the case of GT with spoiler and diffuser with a maximum reduction of 16.53%.

scholarly journals Drag reduction by application of aerodynamic devices in a race car

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Devang S. Nath ◽  
Prashant Chandra Pujari ◽  
Amit Jain ◽  
Vikas Rastogi
Keyword(s):  
Drag Reduction ◽  
Drag Force ◽  
High Speed ◽  
Lift Coefficient ◽  
Three Dimensional ◽  
Fuel Prices ◽  
Race Car ◽  
High Speeds ◽  
Maximum Drag Reduction ◽  
Computational Fluid Dynamics Cfd

AbstractIn this era of fast-depleting natural resources, the hike in fuel prices is ever-growing. With stringent norms over environmental policies, the automotive manufacturers are on a voyage to produce efficient vehicles with lower emissions. High-speed cars are at a stake to provide uncompromised performance but having strict rules over emissions drives the companies to approach through a different route to keep the demands of performance intact. One of the most sought-after ways is to improve the aerodynamics of the vehicles. Drag force is one of the major setbacks when it comes to achieving high speeds when the vehicle is in motion. This research aims to examine the effects of different add on devices on the vehicle to reduce drag and make the vehicle aerodynamically streamlined. A more streamlined vehicle will be able to achieve high speeds and consequently, the fuel economy is also improved. The three-dimensional car model is developed in SOLIDWORKS v17. Computational Fluid Dynamics (CFD) is performed to understand the effects of these add on devices. CFD is carried out in the ANSYS™ 17.0 Fluent module. Drag Coefficient (CD), Lift Coefficient (CL), Drag Force and Lift Force are calculated and compared in different cases. The result of the simulations was analyzed and it was observed that different devices posed several different functionalities, but maximum drag reduction was found in the case of GT with spoiler and diffuser with a maximum reduction of 16.53%.

scholarly journals CFD Modelling of the Thermal Performance of Fruit Packaging Boxes—Influence of Vent-Holes Design

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7990
Author(s):  
Adhiyaman Ilangovan ◽  
João Curto ◽  
Pedro D. Gaspar ◽  
Pedro D. Silva ◽  
Nanci Alves
Keyword(s):  
Shelf Life ◽  
Thermal Performance ◽  
Cold Storage ◽  
Three Dimensional ◽  
Life Extension ◽  
Perishable Products ◽  
Cfd Modelling ◽  
Computational Fluid Dynamics Cfd ◽  
Short Time ◽  
Model Temperature

The shelf life of perishable products depends mainly on the conservation of air temperature. Packaging boxes are usually used to accommodate food products during cold storage and transport and/or display. The design of the vent-holes of the packaging box must promote cold airflow and remove the field heat of the produce after harvest at a short time. This study describes the influence of the vent-holes design and its performance during cold storage. The cooling performance of the different packaging boxes is evaluated experimentally and numerically using Computational Fluid Dynamics (CFD). Three new packaging box configurations with the same size but different vent-holes design (size, shape and position) and a reference box are modelled. The transient three-dimensional CFD model predicts the airflow pattern and temperature distribution within the different packaging boxes. The best thermal performance packaging achieved a fruit model temperature 1.5 K to 5 K lower than the other configurations at the end of 8 h of cooling. These predictions allow the development of new packaging box designs that promote the shelf-life extension of perishable products.

scholarly journals Drag Reduction by Application of Aerodynamic Devices in a Race Car

2020 ◽  
Author(s):  
Devang S. Nath ◽  
Prashant Chandra Pujari ◽  
Amit Jain ◽  
Vikas Rastogi
Keyword(s):  
Drag Force ◽  
Fuel Economy ◽  
High Speed ◽  
Three Dimensional ◽  
Environmental Policies ◽  
Fuel Prices ◽  
Race Car ◽  
Car Model ◽  
High Speeds ◽  
Computational Fluid Dynamics Cfd

Abstract In this era of fast-depleting natural resources, the hike in fuel prices is ever-growing. With stringent norms over environmental policies, the automotive manufacturers are on a voyage to produce efficient vehicles with lower emissions. High-speed cars are at a stake to provide uncompromised performance but having strict rules over emissions drives the companies to approach through a different route to keep the demands of performance intact. One of the most sought-after ways is to improve the aerodynamics of the vehicles. Drag force is one of the major setbacks when it comes to achieving high speeds when the vehicle is in motion. This research aims to examine the effects of different add on devices on the vehicle to reduce drag and make the vehicle aerodynamically streamlined. A more streamlined vehicle will be able to achieve high speeds and consequently, the fuel economy is also improved. The three-dimensional car model is developed in SOLIDWORKS v17. Computational Fluid Dynamics (CFD) is performed to understand the effects of these add on devices. CFD is carried out in the ANSYSTM 17.0 Fluent module. Drag Coefficient (CD) and Drag Force is calculated and is compared in different cases.

scholarly journals Numerical investigation of the jet velocity profile and its influence on the Pelton turbine performance

2019 ◽  
Vol 240 ◽  
pp. 072006 ◽  
Author(s):  
Takashi Kumashiro ◽  
Siamak Alimirzazadeh ◽  
Audrey Maertens ◽  
Ebrahim Jahanbakhsh ◽  
Sebastián Leguizamón ◽  
...  
Keyword(s):  
Velocity Profile ◽  
Numerical Investigation ◽  
Pelton Turbine ◽  
Turbine Performance ◽  
Jet Velocity
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