Producing Mechanism on Flow Regeneration Noise from Muffler Element with Inserted Tube

2012 ◽  
Vol 538-541 ◽  
pp. 1977-1980
Author(s):  
Hai Jun Zhao ◽  
Jia Dong Chang ◽  
Hai Xia Wang ◽  
Qi Li
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Flow Velocity ◽  
Numerical Computation ◽  
Frequency Characteristic ◽  
Low Frequency ◽  
Turbulence Kinetic Energy ◽  
Sound Power ◽  
Structure Parameters ◽  
Constant Distribution

Structure parameters of muffler element with inserted tube are firstly determined, it is analyzed to the inserted length effecting on sound power of flow regeneration noise and frequency characteristic, and distribution feature of flow velocity and turbulence kinetic energy is explored by numerical computation of flow field. It is shown that flow regeneration noise of muffler element with inserted tube forms according to confined incomplete flow-inject, it presents wide frequency band, and its energy focus on middle and low frequency, especially it is about 600Hz, Strouhal Number is 0.5. When its structure parameters is constant, distribution feature of flow velocity and turbulence kinetic energy doesn’t change with flow velocity, and difference is numerical dimension, and turbulence kinetic energy distributes near inserted tube in wall, this is area occurring flow regeneration noise, so producing mechanism of flow regeneration noise from muffler element with inserted tube is achieved.

Simulation on Flow Field Induced by Vibration Surface of Low Frequency

2010 ◽  
Author(s):  
Ling Shen ◽  
Shuhong Liu ◽  
Yulin Wu
Keyword(s):  
Flow Field ◽  
Velocity Distribution ◽  
Numerical Computation ◽  
High Frequency ◽  
Ultrasonic Transducer ◽  
Sewage Treatment ◽  
Low Frequency ◽  
Vibration Source ◽  
Water Tank ◽  
Industrial Cleaning

Ultrasonic cavitation generated by high-frequency ultrasonic transducer is widely studied because this phenomenon could be applied in a great variety of fields, including medical therapy, industrial cleaning as well as sewage treatment. Flow field influenced by vibration source of low frequency, however, is less studied. For the present study, a water tank of 1000×600×500mm is investigated when a vibration surface that represents a transducer of less frequency vibrates in the vicinity of one wall. Numerical computation based on the method of dynamic mesh is applied. Furthermore, two different vibration patterns are simulated, i.e., piston movement and drumhead vibration. Results show different pressure and velocity distribution within water tank when vibration surface is working at various frequencies and amplitudes. Differences of the flow fields are found between these circumstances, and similarity is found with that induced by ultrasonic transducer. Analysis on differences is discussed for further study.

Analysis on Numerical Simulation for Bionic Robot Fish Based on CATIA

2015 ◽  
Vol 742 ◽  
pp. 511-515
Author(s):  
De Jian Li
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Theoretical Analysis ◽  
Flow Velocity ◽  
Experimental Research ◽  
Turbulence Kinetic Energy ◽  
Robot Fish ◽  
Preliminary Research

Based on the problem that there is a relatively small number of analog simulations on swimming of fish a in specific fluid conducted by science researchers, a simulated tuna model is established in this paper, in which CATIA is used to construct the streamline shape of simulated tuna and the method of computational fluid dynamics is utilized to simulate the swimming of tuna in marine environment. Indexes for fluid performance such as pressure on the surface of robot fish, turbulence kinetic energy and flow velocity of fluid around are focused on, and preliminary research on the variation trend of pressure on the robot fish and of turbulence kinetic energy at different velocities is conducted in this paper. Theoretical analysis and experimental research conducted in this paper may provide some references for design of shape of robot fish in the future.

Retarding the decay of temperature in the air flow field during the melt blowing process using a thermal insulation tube

2019 ◽  
Vol 90 (5-6) ◽  
pp. 606-616
Author(s):  
Xibo Hao ◽  
Ying Yang ◽  
Yongchun Zeng
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Flow Field ◽  
Thermal Insulation ◽  
Field Experiments ◽  
Air Flow ◽  
Rapid Decrease ◽  
Turbulence Kinetic Energy ◽  
Melt Blowing

During melt blowing, most of the polymer jet attenuation occurs in the area within 2 cm from the die, due to the rapid decrease of polymer jet temperature. Therefore, keeping the polymer jet temperature above melting point for a longer time is beneficial for its attenuation. Here, a thermal insulation tube with heating ability was introduced into the air flow field during the melt blowing process. The computational fluid dynamics technique was employed to investigate the effects of the thermal insulation tube on the air flow field. It was found that the thermal insulation tube has enhancing effects on the temperature, velocity, and turbulence kinetic energy of the air flow field. Experiments were conducted to examine the fiber diameters of the final nonwovens, the results of which indicates that a die with a thermal insulation tube can achieve a higher polymer jet attenuation and that the heating effect can further enhance the attenuation. Based on the computational fluid dynamics technique, the effects of the tube diameter and length on the temperature, velocity, and turbulence kinetic energy of the air flow field were investigated.

scholarly journals Effect of Mold Width on the Flow Field in a Slab Continuous-Casting Mold with High-Temperature Velocity Measurement and Numerical Simulation

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1943
Author(s):  
Jian-Qiu Liu ◽  
Jian Yang ◽  
Chao Ma ◽  
Yi Guo ◽  
Wen-Yuan He ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Flow Velocity ◽  
Turbulent Kinetic Energy ◽  
Flow Rate ◽  
Gas Flow ◽  
Immersion Depth ◽  
Gas Flow Rate ◽  
Argon Gas ◽  
Slag Entrainment

In this paper, the effects of the width of the mold on the surface velocity, flow field pattern, turbulent kinetic energy distribution, and surface-level fluctuation in the mold were studied with measurement of the flow velocity near the surface of the mold at high temperature with the rod deflection method and numerical calculation with the standard k-ε model coupled with the discrete-phase model (DPM) model for automobile exposed panel production. Under the conditions of low fixed steel throughput of 2.2 ton/min, a nozzle immersion depth of 140 mm, and an argon gas flow rate of 4 L/min, as the width of the mold increases from 880 mm to 1050 mm and 1300 mm, the flow velocity near the surface of the mold decreases. The flow direction changes from the positive velocity with the mold widths of 880 mm and 1050 mm to the unstable velocity with the mold width of 1300 mm. The calculated results are in good agreement with the measured results. The turbulent kinetic energy near the submerged entry nozzle (SEN) gradually increases, and the risk of slag entrainment increases. Under the conditions of high fixed steel throughput of 3.5 ton/min, the SEN immersion depth of 160 mm, and the argon gas flow rate of 10 L/min, as the width of the mold increases from 1600 mm to 1800 mm and 2000 mm, the velocity near the mold surface decreases. The flow velocity at 1/4 of the surface of the mold is positive with the mold width of 1600 mm, while the velocities are negative with the widths of 1800 mm and 2000 mm. The calculated results are basically consistent with the measured results. The high turbulent kinetic energy area near the nozzle expands to a narrow wall, and the risk of slag entrainment is significantly increased. In both cases of low and high fixed steel throughput, the change rules of the flow field in the mold with the width are basically the same. The argon gas flow rate and the immersion depth of SEN should be adjusted reasonably to optimize the flow field in the mold with different widths under the same fixed steel throughput in the practical production.

Calculation and Spatial Distributing Simulation of Turbulence’s Kinetic Energy Entropy in Strengthen Grinding

2011 ◽  
Vol 474-476 ◽  
pp. 228-233
Author(s):  
Zhong Wei Liang ◽  
Xiao Chu Liu ◽  
Jian Hua Tao ◽  
Chun Wang
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Three Dimensional ◽  
Turbulence Kinetic Energy ◽  
Confined Space ◽  
Technological Parameters ◽  
Energy Entropy ◽  
Fluid Theory ◽  
Characteristic Signal ◽  
The Given

Analysis of turbulence characteristics in the confined space has important influence on strengthen grinding, and it is a main point and difficult point in the research of fluid theory. For the purpose of studying the technological parameters of strengthen grinding, and obtaining its characteristic signal group, calculation and spatial distributing simulation of turbulence’s kinetic energy entropy in the confined space is investigated. Through the meshing of flow field the turbulence particle is gotten, then with the velocity and direction of particle motion, turbulence kinetic energy under model and the given boundary conditions is calculated. After determining the kinetic energy’s three-dimensional projecting components and the energy value’s occurrence probability, the integrating process in the flow field’s effective space is conducted then a computing formula of kinetic energy entropy is deduced. In experiment the turbulence caused by strengthen grinding is used as an example, the kinetic energy entropy is calculated and revised in the whole flow field; and the computer simulating of entropy’s spatial distribution is conducted in Fluent 6.2.23 environment. Thus the influence mechanism and relationship between turbulence kinetic energy entropy’s calculation and its spatial distributing simulation are established, and the technology reference and research idea for turbulence monitoring in strengthen grinding are also be provided.

scholarly journals Spectroscopic Techniques versus Pitot Tube for the Measurement of Flow Velocity in Narrow Ducts

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7349
Author(s):  
Francesco D’Amato ◽  
Silvia Viciani ◽  
Alessio Montori ◽  
Marco Barucci ◽  
Carmen Morreale ◽  
...  
Keyword(s):  
Flow Field ◽  
Flow Velocity ◽  
Pitot Tube ◽  
Optical Measurements ◽  
Trace Gas ◽  
Dual Function ◽  
Spectroscopic Techniques ◽  
Gas Composition ◽  
Flow Conditions ◽  
Theoretical Simulation

In order to assess the limits and applicability of Pitot tubes for the measurement of flow velocity in narrow ducts, e.g., biomass burning plants, an optical, dual function device was implemented. This sensor, based on spectroscopic techniques, targets a trace gas, injected inside the stack either in bursts, or continuously, so performing transit time or dilution measurements. A comparison of the two optical techniques with respect to Pitot readings was carried out in different flow conditions (speed, temperature, gas composition). The results of the two optical measurements are in agreement with each other and fit quite well the theoretical simulation of the flow field, while the results of the Pitot measurements show a remarkable dependence on position and inclination of the Pitot tube with respect to the duct axis. The implications for the metrology of small combustors’ emissions are outlined.

scholarly journals Study on the characteristics of the pressure fluctuations and their contribution to turbulence kinetic energy

2021 ◽  
pp. 105634
Author(s):  
Zhuorui Wei ◽  
Hongsheng Zhang ◽  
Yan Ren ◽  
Qianhui Li ◽  
Xuhui Cai ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Pressure Fluctuations ◽  
Turbulence Kinetic Energy

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

Radial Flow Velocity Field for Predicting Upper-Bound Solutions for Plane Strain Extrusion

1968 ◽  
Vol 90 (1) ◽  
pp. 45-50
Author(s):  
R. G. Fenton
Keyword(s):  
Velocity Field ◽  
Flow Field ◽  
Flow Velocity ◽  
Plane Strain ◽  
Upper Bound ◽  
Radial Flow ◽  
Flow Velocity Field ◽  
Wide Range ◽  
Ram Pressure ◽  
Considerable Range

The upper bound of the average ram pressure, based on an assumed radial flow velocity field, is derived for plane strain extrusion. Ram pressures are calculated for a complete range of reduction ratios and die angles, considering a wide range of frictional conditions. Results are compared with upper-bound ram pressures obtained by considering velocity fields other than the radial flow field, and it is shown that for a considerable range of reduction ratios and die angles, the radial flow field yields better upper bounds for the average ram pressure.

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