Oscillation Caused by Vortex Cavitation in a Double-Suction Volute Pump

2011 ◽  
Author(s):  
Kazuhiro Tanaka ◽  
Akira Inoue ◽  
Toshiyuki Sato ◽  
Takahide Nagahara ◽  
Masaki Fuchiwaki ◽  
...  
Keyword(s):  
Numerical Model ◽  
Multiphase Flow ◽  
Numerical Simulations ◽  
Characteristic Frequency ◽  
Experimental Investigations ◽  
Baffle Plate ◽  
Fixed Frequency ◽  
Flow Equations ◽  
Commercial Code ◽  
Collapse Process

This study highlights a mechanism of the vortex cavitation occurrence from the baffle plate, the end of the suction duct, in a double-suction volute pump and a relationship between pump oscillation and the cavitation occurrence. In this study, full 3D numerical simulations have been performed using a commercial code inside the pump from the inlet of suction duct to the outlet of delivery duct. The numerical model is based on combination of multiphase flow equations with the truncated version of Rayleigh-Plesset model predicting the complicated growth and collapse process of cavity bubbles. The vortex cavitation has the characteristic frequency based on the impeller rotation and has much influence on the pump oscillation, however at over discharge range the vortex cavitation does not collapse, because the cavitation runs into and combines with another cavitation generated in the impeller shroud, and the fixed frequency of the pump oscillation is reduced. The experimental investigations have also been performed on the cavitating flow to evaluate the numerical results and the both results agree well.

A New Tire Model to Predict Vibration Emission of Counterbalance Trucks

2000 ◽  
Vol 28 (2) ◽  
pp. 119-137 ◽  
Author(s):  
P. Lemerle ◽  
P. Mistrot
Keyword(s):  
Numerical Model ◽  
Numerical Simulations ◽  
Close Agreement ◽  
Industrial Sector ◽  
Tire Model ◽  
Suspension Systems ◽  
Truck Tires ◽  
Pneumatic Tires

Abstract Counterbalance trucks are machines in widespread use in every industrial sector. Unlike cars, they are not designed with suspension systems. Consequently, they are considered to be high vibrating vehicles. Nevertheless, like suspension seats, tires can be selected as suspension parts. This paper presents a new numerical model for the analysis of the vibratory behavior of counterbalance truck tires. This model was intended to be a part of a fork lift truck model, including axles, chassis, and cabin. All the results reported here show a close agreement between measurements and numerical simulations. Thus, it can predict the vibration emission values at the driving position and is used to compare the efficiency of solid tires with pneumatic tires in terms of transmitted vibration levels.

scholarly journals Wind shear over the Nice Côte d'Azur airport: case studies

2013 ◽  
Vol 13 (9) ◽  
pp. 2223-2238 ◽  
Author(s):  
A. Boilley ◽  
J.-F. Mahfouf
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Numerical Simulations ◽  
Wind Shear ◽  
Horizontal Wind ◽  
Wind Profiler ◽  
Measurement Campaign ◽  
Wind Lidar ◽  
Real Time Applications ◽  
Wind Shears

Abstract. The Nice Côte d'Azur international airport is subject to horizontal low-level wind shears. Detecting and predicting these hazards is a major concern for aircraft security. A measurement campaign took place over the Nice airport in 2009 including 4 anemometers, 1 wind lidar and 1 wind profiler. Two wind shear events were observed during this measurement campaign. Numerical simulations were carried out with Meso-NH in a configuration compatible with near-real time applications to determine the ability of the numerical model to predict these events and to study the meteorological situations generating an horizontal wind shear. A comparison between numerical simulation and the observation dataset is conducted in this paper.

scholarly journals Drag reduction in a class 8 truck - scaled down model

2018 ◽  
Vol 172 ◽  
pp. 01003
Author(s):  
R Vishwa Krishna. ◽  
R Suwathy. ◽  
M Pragadeesh. ◽  
M Venkatesan.
Keyword(s):  
Numerical Model ◽  
Drag Coefficient ◽  
Heavy Duty ◽  
Commercial Vehicles ◽  
Heavy Load ◽  
Ansys Fluent ◽  
Commercial Code ◽  
Class 8 Truck ◽  
Gap Width ◽  
Front Radius

Trucks are heavy load vehicles used mainly for commercial transport operations. There are several classes of heavy duty commercial vehicles classified based on the weight loaded. More than 50% of the engine output power in such trucks is utilized to overcome the drag. Drag force in automobiles is the resistance offered by air on vehicles at higher speeds. Class 8 trucks suffer higher drag when compared to other classes. In the present work, a numerical model is developed using a commercial code ANSYS FLUENT to predict the drag coefficient value. The effects of gap width and cab front radius with a constant fairing is analysed using the numerical model developed. A Class 8 model truck with minimal drag coefficient having constant fairing and optimized gap width between the trailer and cab is proposed.

URANS Simulations and Experimental Investigations on Unsteady Aerodynamic Effects in the Blade Tip Region of a Shrouded Fan Configuration

2017 ◽  
Author(s):  
Gi-Don Na ◽  
Frank Kameier ◽  
Nils Springer ◽  
Michael Mauß ◽  
C. O. Paschereit
Keyword(s):  
Applied Sciences ◽  
Numerical Simulations ◽  
Aerodynamic Performance ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Acoustic Measurements ◽  
Noise Emission ◽  
Industrial Partner ◽  
University Of Applied Sciences ◽  
Blade Tip

The acoustical characteristics of cooling fans are an essential criterion of product quality in the automotive industry. Fan modules have to suffice growing customer expectations which are reflected in the comfort requirements set by car manufacturers around the world. In order to locate dominant acoustic sources and to reduce the noise emission generated by a shrouded fan configuration, numerical simulations and experimental investigations are performed. The working approach considers variously modified fan geometries and their evaluation regarding arising vortex flow phenomena and their effect on a decreased sound pressure level (SPL) in consideration of an improvement or the constancy of aerodynamic fan performance. Particular emphasis lies on the analysis of secondary flows in the blade tip region by post-processing CFD-results. Due to the large number of geometrical modifications investigated and the importance of highly resolved eddy structures, a hybrid approach is chosen by applying the SAS-SST turbulence model in URANS simulations. The SAS (Scale Adaptive Simulation) delivers LES (Large Eddy Simulation) content in unsteady regions of a RANS-simulation and exhibits not nearly the high computational effort needed to perform a full scale LES. An assessment of the actual propagation of noise emission into the far-field is made by performing experimental investigations on the most promising modifications. The acoustic measurements are carried out in a fan test stand in the anechoic chamber of Duesseldorf University of Applied Sciences. The aerodynamic performance is measured in a fan test rig with an inlet chamber setup in accordance to ISO 5801. The measured acoustical and aerodynamic performances are validated by the industrial partner. The results of the acoustic measurements are in turn utilized to determine indicators of noise radiation in the numerical simulation. Within this work an innovative geometry modification is presented which can be implemented into shrouded fan configurations with backward-skewed blades. The new design exhibits a reduced SPL (A-weighted) of approx. 4 dB over the entire operating range while showing no significant deterioration on the aerodynamic performance. While the design was registered for patent approval cooperatively by the industrial partner and Duesseldorf University of Applied Sciences, further investigations regarding variations of design parameters are performed and presented in this paper. All numerical simulations are performed with ANSYS CFX, a commercial solver widely spread in the industry. Methods similar to those shown in this work can be implemented in the design phase of axial fans in order to develop acoustically optimized fan geometries.

scholarly journals Thermal Behavior of an Extensive Green Roof: Numerical Simulations and Experimental Investigations

2016 ◽  
Vol 34 (S2) ◽  
pp. S226-S234 ◽  
Author(s):  
Antonio Gagliano ◽  
Francesco Nocera ◽  
Maurizio Detommaso ◽  
Gianpiero Evola
Keyword(s):  
Thermal Behavior ◽  
Numerical Simulations ◽  
Green Roof ◽  
Experimental Investigations ◽  
Extensive Green Roof

Multifidelity Recursive Cokriging for Dynamic Systems' Response Modification

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Luigi Bregant ◽  
Lucia Parussini ◽  
Valentino Pediroda
Keyword(s):  
Numerical Model ◽  
Numerical Simulations ◽  
Dynamic Systems ◽  
System Optimization ◽  
The Other ◽  
Experimental Measurements ◽  
Reciprocal Influence ◽  
Tests And Measurements ◽  
Invaluable Tool ◽  
Mixed Approach

In order to perform the accurate tuning of a machine and improve its performance to the requested tasks, the knowledge of the reciprocal influence among the system's parameters is of paramount importance to achieve the sought result with minimum effort and time. Numerical simulations are an invaluable tool to carry out the system optimization, but modeling limitations restrict the capabilities of this approach. On the other side, real tests and measurements are lengthy, expensive, and not always feasible. This is the reason why a mixed approach is presented in this work. The combination, through recursive cokriging, of low-fidelity, yet extensive, numerical model results, together with a limited number of highly accurate experimental measurements, allows to understand the dynamics of the machine in an extended and accurate way. The results of a controllable experiment are presented and the advantages and drawbacks of the proposed approach are also discussed.

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