Prediction of vibration radiation noise from shell of straw crushing machine

2021 ◽  
pp. 095745652110004
Author(s):  
Lun Xuejian ◽  
Li Can ◽  
Zhai Zhiping ◽  
Lan Yuezheng ◽  
Gan Shiming
Keyword(s):  
Flow Field ◽  
Fundamental Frequency ◽  
Design Method ◽  
Excitation Frequency ◽  
Low Noise ◽  
Coupled Flow ◽  
Measuring Point ◽  
Harmonic Frequencies ◽  
Radiation Noise ◽  
Vibration Noise

In order to predict the radiation noise of the vibrating shell of the straw crusher in the design phase, the computational fluid dynamics–discrete element coupling method is initially used to simulate the airflow–straw coupled flow field in the straw crusher, and the pulsating pressure generated by the coupled flow field is applied to the inner surface of the shell of the crusher. Then, the harmonic response of the shell is analyzed, and its results are used to be the acoustic boundary condition. Finally, the finite element and acoustic boundary element combined test methods are used to predict vibration noise of the straw crusher shell. The results indicate that the produced vibration noise of the straw crusher shell changes as the excitation frequency of the rotor rotation changes. The maximum vibration noise is achieved at the excitation fundamental frequency, and radiation noises at the harmonic frequencies decrease as the frequency increases. The simulated value of the sound pressure level of each measuring point at the excitation fundamental frequency and harmonic frequencies is basically the same as those of the experiment. Moreover, it is found that the maximum difference between the simulated and experimental value of measuring points is 1.69 dB(A). Therefore, it is concluded that the numerical model of the vibration radiation noise is accurate. The vibration noise of the shell at the inlet is the largest, and the main noise source of the vibration radiation noise is the dipole sound source of the rotating hammer rotor. The corresponding design method provides the reference for the low-noise design of straw crushers.

A new method of fluxgate signal extraction

2017 ◽  
Vol 2017 (45) ◽  
pp. 83-89
Author(s):  
A.A. Marusenkov ◽  
Keyword(s):  
High Frequency ◽  
Second Harmonic ◽  
Excitation Frequency ◽  
Low Noise ◽  
Measuring System ◽  
Signal Extraction ◽  
Fluxgate Magnetometer ◽  
New Approach ◽  
Average Value ◽  
The Time Domain

Using dedicated high-frequency measuring system the distribution of the Barkhausen jumps intensity along a reversal magnetization cycle was investigated for low noise fluxgate sensors of various core shapes. It is shown that Barkhausen (reversal magnetization) noise intensity is strongly inhomogeneous during an excitation cycle. In the traditional second harmonic fluxgate magnetometers the signals are extracted in the frequency domain, as a result, some average value of reversal magnetization noises is contributed to the output signals. In order to fit better the noise shape and minimize its transfer to the magnetometer output the new approach for demodulating signals of these sensors is proposed. The new demodulating method is based on information extraction in the time domain taking into account the statistical properties of cyclic reversal magnetization noises. This approach yields considerable reduction of the fluxgate magnetometer noise in comparison with demodulation of the signal filtered at the second harmonic of the excitation frequency.

scholarly journals Numerical and Experimental Analysis of Flow and Pulsation in Hump Section of Siphon Outlet Conduit of Axial Flow Pump Device

2021 ◽  
Vol 11 (11) ◽  
pp. 4941
Author(s):  
Fan Yang ◽  
Yiqi Zhang ◽  
Yao Yuan ◽  
Chao Liu ◽  
Zhongbin Li ◽  
...  
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Vortex Structure ◽  
Pressure Fluctuation ◽  
Axial Flow ◽  
Mean Value ◽  
Hydraulic Loss ◽  
Pressure Amplitude ◽  
Measuring Point ◽  
Outlet Conduit

In order to study the variation law of the flow field and pressure fluctuation in the hump section of the siphon outlet conduit, the flow field characteristics and frequency spectrum characteristics of the flow field were analyzed by combining a physical model test and numerical simulation under the conditions of the interaction between the axial flow pump and siphon outlet conduit, and the influence of the residual circulation at the outlet of the guide vane on the siphon outlet flow was investigated. Based on the influence of the flow field and hydraulic loss in the conduit, the equivalent surface method based on the Q criterion was used to analyze the vortex structure in the siphon outlet conduit and to analyze the internal vortex state. The results showed that with the increase of the flow rate, the intensity of the vortices in the cross-section of the hump section of the siphon outlet conduit decreased gradually, the average velocity circulation decreased gradually and the axial velocity distribution uniformity increased and tended to be stable; water flow stratification existed under three characteristic conditions with no circulation, and the hydraulic loss was greater with the circulation flow while it had a circulation under the small flow condition. Under the low flow rate conditions, the hydraulic loss was 6.6 times higher under the condition of circulation than without. Under a high flow condition, it was 1.3 times. Under the condition of a small flow rate, the vortex structure was distributed centrally at the inlet of the flow conduit, and under the other two characteristic conditions, the vortex structure mostly appeared as a strip; the pressure fluctuation in the hump section had obvious periodicity, and with the increase of the flow rate, the maximum pressure fluctuation amplitude in the hump section decreased gradually; with the decrease of the rotational speed, the pressure amplitude at the same measuring point in the hump section decreased gradually and at the optimum condition. Under the following conditions, the mean value of the pressure amplitude at the top of the hump section was reduced by 69.63%, and the mean value of the pressure amplitude at the bottom of the hump section was reduced by 63.5%. Under all the calculation conditions, the main frequency of pulsation at each measuring point of the hump section was twice the frequency of the rotation.

Effects of Acoustic Excitation on a Swirling Diffusion Flame

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Michael E. Loretero ◽  
Rong F. Huang
Keyword(s):  
Flow Field ◽  
Bluff Body ◽  
Excitation Frequency ◽  
Excitation Amplitude ◽  
Mie Scattering ◽  
Flame Length ◽  
Laser Doppler Velocimeter ◽  
Scattering Method ◽  
Acoustic Excitation ◽  
Characteristic Modes

A swirling double concentric jet is commonly used for nonpremixed gas burner application for safety reasons and to improve the combustion performance. Fuel is generally spurted at the central jet while the annular coflowing air is swirled. They are normally separated by a blockage disk where the bluff-body effects further enhance the recirculation of hot gas at the reaction zone. This paper aims to experimentally investigate the behavior of flame and flow in a double concentric jet combustor when the fuel supply is acoustically driven. Laser-light sheet assisted Mie scattering method has been used to visualize the flow, while the flame lengths were measured by a conventional photography technique. The fluctuating velocity at the jet exit was measured by a two-component laser Doppler velocimeter. Flammability and stability at first fuel tube resonant frequency are reported and discussed. The evolution of flame profile with excitation level is presented and discussed, together with the reduction in flame length. The flame in the unforced reacting axisymmetric wake is classified into three characteristic modes, which are weak swirling flame, lifted flame, and transitional reattached flame. These terms reflect their primary features of flame appearances, and when the acoustic excitation is applied, the flame behaviors change with the excitation frequency and amplitude. Four additional characteristic modes are identified; e.g., at low excitation amplitudes, wrinkling flame with a blue annular film is observed because the excitation induces vortices in the central fuel jet and hence gives rise to the wrinkling of flame. The central jet vortices become larger with the increase in excitation amplitude and thus lead to a wider and shorter flame. If the excitation amplitude is increased above a certain value, the central jet vortices change the rotation direction and pacing with the annular jet vortices. These changes in the flow field induce large turbulent intensity and mixing and therefore make the flame looks blue and short. Further increase in the excitation amplitude would lift the flame because the flow field would be dramatically modified.

Development of a New Design Method for High Efficiency Swept Low Pressure Axial Fans With Small Hub/Tip Ratio

2014 ◽  
Author(s):  
Thore Bastian Lindemann ◽  
Jens Friedrichs ◽  
Udo Stark
Keyword(s):  
High Efficiency ◽  
Design Method ◽  
Tangential Velocity ◽  
Pressure Rise ◽  
Low Pressure ◽  
Aerodynamic Performance ◽  
Low Noise ◽  
Angle Distribution ◽  
Sweep Angle ◽  
Reduced Pressure

For a competitive low pressure axial fan design low noise emission is as important as high efficiency. In this paper a new design method for low pressure fans with a small hub to tip ratio including blade sweep is introduced and discussed based on experimental investigations. Basis is an empirical axial and tangential velocity distribution at the rotor outlet combined with a distinctive sweep angle distribution along the stacking line. Several fans were designed, built and tested in order to analyze the aerodynamic as well as the aeroacoustic behavior. For the aerodynamic performance particular attention was paid to compensate the influence of reduced pressure rise and efficiency due to increasing blade sweep. This was achieved by a method of increasing the blade chord depending on the local sweep angle which is based on single airfoil data. The tested fans without this compensation revealed a significant noise reduction effect of up to approx. 6 dB(A) for a tip sweep angle of 64° which was accompanied by an unsatisfactory effect of reduced overall aerodynamic performance. The second group of fans did not only confirm the method of the aerodynamic compensation by a nearly unchanged pressure rise and efficiency characteristic but also revealed an increased aeroacoustic benefit of in average 9.5 dB(A) compared to the unswept version. Beside the overall characteristics the individual differences between the designs are also discussed using results of wall pressure measurements which show some significant changes of the blade tip flow structure.

scholarly journals Semi-Inverse Design of Compressor Cascades, Including Supersonic Inflow

1990 ◽  
Author(s):  
A. Kirschner ◽  
H. Stoff
Keyword(s):  
Flow Field ◽  
Design Method ◽  
Axisymmetric Flow ◽  
Three Dimensional ◽  
Design Procedure ◽  
Meridional Plane ◽  
Simple Method ◽  
Blade Loading ◽  
Through Flow ◽  
Blade Element

A cascade design-method is presented which complements the meridional through-flow design procedure of turbomachines. Starting from an axisymmetric flow field and the streamline geometry in the meridional plane this simple method produces a solution for the quasi three-dimensional flow field and the blade-element geometry on corresponding stream surfaces. In addition, it provides intra-blade data on loss and turning required for a consistent design and a convenient means of optimizing blade loading. The purpose of this paper is to describe the theoretical basis of the method and to illustrate its application in the design of transonic compressors.

Design Method for Subsonic and Transonic Cascade With Prescribed Mach Number Distribution

1992 ◽  
Vol 114 (3) ◽  
pp. 553-560 ◽  
Author(s):  
O. Le´onard ◽  
R. A. Van den Braembussche
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Pressure Distribution ◽  
Velocity Component ◽  
Design Method ◽  
Normal Velocity ◽  
Flow Solver ◽  
Number Distribution ◽  
Mach Number Distribution ◽  
Transonic Cascade

A iterative procedure for blade design, using a time marching procedure to solve the unsteady Euler equations in the blade-to-blade plane, is presented. A flow solver, which performs the analysis of the flow field for a given geometry, is transformed into a design method. This is done by replacing the classical slip condition (no normal velocity component) by other boundary conditions, in such a way that the required pressure or Mach number distribution may be imposed directly on the blade. The unknowns are calculated on the blade wall using the so-called compatibility relations. Since the blade shape is not compatible with the required pressure distribution, a nonzero velocity component normal to the blade wall evolves from the new flow calculation. The blade geometry is then modified by resetting the wall parallel to the new flow field, using a transpiration technique, and the procedure is repeated until the calculated pressure distribution has converged to the required one. Examples for both subsonic and transonic flows are presented and show a rapid convergence to the geometry required for the desired Mach number distribution. An important advantage of the present method is the possibility to use the same code for the design and the analysis of a blade.

scholarly journals Optimal design for the dual slot die in melt blowing process

2014 ◽  
Vol 18 (5) ◽  
pp. 1714-1715
Author(s):  
Li-Li Wu ◽  
Ting-Ting Cheng ◽  
Chuan Xu ◽  
Ting Chen
Keyword(s):  
Experimental Design ◽  
Optimal Design ◽  
Flow Field ◽  
Design Method ◽  
Air Flow ◽  
Variance Analysis ◽  
Orthogonal Experimental Design ◽  
Melt Blowing ◽  
Experimental Design Method ◽  
Slot Die

The parameters of the dual slot die in an industrial melt blowing equipment are designed optimally using the orthogonal experimental design method. The air flow fields of different die parameters are simulated. Effects of the die parameters are analyzed using variance analysis. The results show that the inset distance and slot width have significant effects on the air flow field while effect of the slot angle is unremarkable.

Aerodynamic Design and Optimization of Pipe Diffuser for a High-Loading Centrifugal Compressor

2017 ◽  
Author(s):  
Xi Yang ◽  
Dong-hai Jin ◽  
Xing-min Gui
Keyword(s):  
Flow Field ◽  
Design Method ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Simulation Software ◽  
Field Analysis ◽  
Superior Performance ◽  
Critical Cross Section ◽  
Isentropic Efficiency ◽  
Vane Diffuser

Pipe diffuser draws more attentions these years as the stage pressure ratio and loads grow, since it is known that the pipe diffuser has a superior performance to the traditional vane diffuser as the diffuser inlet flow field is transonic or supersonic. Generally speaking, when the pressure ratio is high enough to give rise to the emergence of a critical cross-section, it would usually be in the diffuser, closing to the leading edge other than in the impeller. Therefore, the diffuser would have a significant impact on stage choke margin and its performance while be difficult to design and to match the impeller with satisfaction. To address the problem, a preliminary geometry design method for pipe diffuser is presented in this paper. In this paper, the performance and flow field analysis are based on numerical simulation carried out by Numeca, a commercial simulation software. For verified the calculated results′ reliability and grid independence, corresponding calculations and comparisons are conducted and discussed. Then, the performance of stage with pipe diffuser is compared with the stage with vane diffuser. Next, the specific effects of incidence on the performance and flow field are analyzed and discussed respectively. At last, an optimized aerodynamic structure of pipe diffuser is presented. As shown in the CFD results, the stage peak isentropic efficiency can reach up to 83.65% with the stage total pressure ratio slightly increased from 6.50 to 6.78, which means 4.29% of isentropic efficiency was raised by substituting the pipe diffuser for the vane diffuser.

scholarly journals Performance Evaluation of a Resonant-integrated Pumping System

2018 ◽  
Vol 202 ◽  
pp. 02009
Author(s):  
Vincent Chieng-Chen Lee
Keyword(s):  
Performance Evaluation ◽  
Excitation Frequency ◽  
Pressure Head ◽  
Low Noise ◽  
Integrated System ◽  
Positive Outcomes ◽  
Pumping System ◽  
At Resonance ◽  
Impedance Pump ◽  
Maximum Amplification

Impedance pump is a simple valve-less pumping mechanism; it offers a low energy, low noise alternative at both macro- and micro-scale devices. It is also demonstrated to be a promising new technique for producing and amplifying net flow. There have been research studying the effects of series-connected impedance pump, where an increase in net flow is exhibited. In this study, an integrated system of conventional pump and impedance pump is introduced. This paper describes the performance evaluation of this integrated pumping system, with emphasis on the amount of amplification induced as a function of Womersley number (normalized excitation frequency) and normalized pressure head. Due to the nature of the resonant valve-less impedance pump, the integrated pumping system exhibits similar behaviour and characteristics as an impedance pump, such as the pulsatile nature of net flow. Results show positive outcomes where maximum amplification of 91.7% is demonstrated at resonance.

Sign in / Sign up

Export Citation Format

Share Document