scholarly journals Study of physical and mechanical properties of working blades material effect of the noise from the mine axial fan

2020 ◽  
pp. 100-107
Author(s):  
Kochneva Liudmila ◽  
◽  
Tauger Vitalii ◽  
Volkov Evgenii ◽  
◽  
...  
Keyword(s):  
Sound Pressure ◽  
Mechanical Characteristics ◽  
Physical And Mechanical Properties ◽  
Low Noise ◽  
Sound Level ◽  
Axial Fan ◽  
External Influences ◽  
Noise Characteristics ◽  
Working Blades ◽  
Physical And Mechanical Characteristics

Introduction. The high level of sound pressure created by an industrial axial fan negatively affects the performance of people, leads to a decrease in attentiveness, and provokes production errors. The desire to use small-sized and high-performance turbomachines leads to the need to find ways to create ventilation units with a reduced noise level. Research methodology. One promising way to influence the noise characteristics of axial machines is to prevent resonant vibrations of the working blades due to the manufacture of a material with calculated physical and mechanical characteristics. To date, a mathematical model of the blade as an elastic element has been constructed, which allows us to determine the frequency of its own vibrations. Comparison of this ISSN 0536-1028 «Известия вузов. Горный журнал», № 5, 2020 107 frequency with the frequency of external influences will allow us to conclude about the probability of entering the blade into resonance with external influences. Results. In order to test the theoretical positions, an experiment was performed in which the sound pressure created by geometrically identical impellers was measured: aluminum, which is included in the fan delivery, and composite. Conclusions. It was found that equipping the fan with a wheel with composite blades can significantly reduce the sound level, which confirms the prospects for creating low-noise axial fans by making working blades of a material with calculated physical and mechanical characteristics.

Effect of MgO•Sb2O5 on Fire Resistance and Physical and Mechanical Properties of Cable PVC-Plasticate

2021 ◽  
Vol 899 ◽  
pp. 557-562
Author(s):  
Timur A. Borukaev ◽  
Luiza I. Kitieva ◽  
Abubekir Kh. Shaov ◽  
A.A. Kyarov
Keyword(s):  
Mechanical Properties ◽  
Fire Resistance ◽  
Mechanical Characteristics ◽  
Negative Impact ◽  
Physical And Mechanical Properties ◽  
Antimony Oxide ◽  
Magnesium Carbonate ◽  
Physical And Mechanical Characteristics

Based on magnesium carbonate and antimony oxide (V), MgO•Sb2O5 was obtained. In the formulation of fire-resistant cable PVC-plasticate, antimony (III) oxide was replaced by MgO•Sb2O5 and the fire resistance and physical and mechanical properties of the resulting compound were investigated. It is shown that the replacement of antimony (III) oxide in the composition of PVC cable compound MgO•Sb2O5 leads to the production of a compound that is not inferior in its characteristics to the original plastic compound. In particular, the fire resistance of cable PVC-plasticate, standard industrial formulation and with the obtained MgO•Sb2O5, is practically the same (OI=32%). It has been established that the physical and mechanical characteristics of the cable compound, when replacing antimony oxide (III) with MgO•Sb2O5 in the formulation, remain at the level of the original compound, while MgO×Sb2O5 will have a less negative impact on the environment.

Optimization of Low Noise Blade of Small Axial Fan at Low Reynolds Number

2021 ◽  
Vol 263 (6) ◽  
pp. 236-256
Author(s):  
Peixun Yu ◽  
Junqiang Bai ◽  
Xiao Han
Keyword(s):  
Sound Pressure Level ◽  
Optimization Design ◽  
Sound Pressure ◽  
Computational Cost ◽  
Low Noise ◽  
Pressure Level ◽  
Multidisciplinary Optimization ◽  
Axial Fan ◽  
Aerodynamic Efficiency ◽  
Cooling Fan

A multidisciplinary optimization design to simultaneously enhance the aeroacoustic and aerodynamic performance of an cooling fan is performed. The flow analysis of the cooling fan is conducted by solving three dimensional steady-state RANS equations with shear-stress transport turbulence model. Based on the results of the steady flow, aeroacoustic analysis is performed by using the Hanson and Brooks model. A multi-objective optimization is performed to simultaneously improve the efficiency and reduce the sound pressure level through an improved non-dominated sorting gentic algorithm. A Kriging surrogate model is used to approximate the function value while reducing computational cost. Series of optimum designs on the pareto front yielded increases in efficiency and decreases in the sound pressure level compared to the reference design. Through numerical analysis and experimental test, the aerodynamic efficiency is increased by 5% and the total sound pressure level is reduced by 4dB without loss of air volume for the selected optimized cooling fan. The thining of rotor boundary layer and inward load shift are the main factors to improve aerodynamic efficiency and reduce noise of the cooling fan.

Study of the Physical and Mechanical Characteristics of the Ice Cover

2019 ◽  
Vol 974 ◽  
pp. 482-487
Author(s):  
A.S. Vasilyev ◽  
V.L. Zemlyak ◽  
V.M. Kozin
Keyword(s):  
Mechanical Characteristics ◽  
Bending Strength ◽  
Winter Season ◽  
Physical And Mechanical Properties ◽  
Ice Cover ◽  
The Arctic ◽  
Structural Failure ◽  
Extreme North ◽  
Far Eastern ◽  
Physical And Mechanical Characteristics

The construction of crossing ferry landings across the Arctic Shelf and the regions located in the Extreme North or Far North, as well as the Siberian and Far Eastern rivers during the winter season is a difficult task of immediate concern. Nevertheless, it is necessary to learn the ice mechanical characteristics in order to examine the bearing capacity of the ice cover at the crossing ferry landings aimed at their establishment and strengthening. The purpose of the paper is to observe the physical and mechanical features of the ice cover by means of doing simulated experiments and verifying their validity using a computational model. The research performed the studies on Young’s modulus of ice definition and bending strength. Ice beam samples were used in the simulated experiments. Their physical and mechanical properties were put to the tests carried out with a special loading device. There was a structural failure of ice beam samples influenced by pure bending. The authors performed numerical computations on the ground of the data obtained by ANSYS software. The calculations resulted in determining condition of the stress-strain state of the samples at any time of loading up to their complete breaking-up. The efficiency of the algorithm is proved by comparing numerical calculations to simulated experimental data.

Evaluation of Noise Characteristics of Drainage and Water Supply Systems in Apartment Bathrooms

2014 ◽  
Vol 1025-1026 ◽  
pp. 987-990
Author(s):  
Jun Oh Yeon ◽  
Kyoung Woo Kim ◽  
Kwan Seop Yang ◽  
Byung Kwon Lee
Keyword(s):  
Water Supply ◽  
Noise Level ◽  
Drainage System ◽  
Low Noise ◽  
Sound Level ◽  
Water Supply Systems ◽  
Apartment Building ◽  
Noise Characteristics ◽  
Measurement Results ◽  
Supply Systems

We have developed a low-noise drainage system, which was installed in bathrooms of apartment building units as well as in a mock-up test building, to evaluate the noise level in order to reduce the noise produced in the bathrooms of multiunit dwellings. The drainage system installed in the mock-up building consists of six types of detachable drains, and the level of noise produced during toilet use in the upper unit was measured in the lower unit. The measurement results showed that low-noise drainage 4 exhibited the Leq(equivalent continuous sound level) at 34.7 dB(A). The noise measurement results of various types of low-noise drains installed in an apartment building showed that the Leqduring toilet use was 46.7 dB(A) on average, and the Leqduring sink use was 40.5 dB(A) on average.

On the influence of the shaped charge liner manufacture technology on the high-speed element characteristics

2020 ◽  
Author(s):  
V.I. Kolpakov ◽  
N.A. Kudyukov
Keyword(s):  
High Speed ◽  
Mechanical Characteristics ◽  
Physical And Mechanical Properties ◽  
Shaped Charge ◽  
Design Parameters ◽  
Geometrical Parameters ◽  
Liner Material ◽  
Metal Spinning ◽  
Cold Stamping ◽  
Physical And Mechanical Characteristics

The paper introduces the results of numerical simulation of the functioning of shaped charges, whose liners are made of different materials. As a result of their functioning, these charges form high-speed elements. Typically, liners for such charges are produced by the cold stamping technology. An alternative method for producing the liners is metal spinning. Moreover, a spin formed liner is expected to have higher physical and mechanical properties compared to a stamped liner made of the same material and having the same geometrical parameters. To reveal the patterns of molding high-speed elements from stamped and spin formed liners, the action of shaped charges comprised of steel or copper segmental liners of small bending, was simulated numerically using the apparatus of continuum mechanics. The influence of the liner manufacture method was taken into account by varying the values of the physical and mechanical characteristics of the liner material. The design parameters of the simulated charge, with the exception of the liner bending, during the calculation study remained unchanged and corresponded to the parameters of the currently used samples. Following the numerical experiments results, the study shows that the elements molded from spin formed liners are less likely to become fractured while being formed and are also more integral (continuous) in comparison to the elements molded from stamped shaped charge liners.

Physical and mechanical characteristics of cement mortars and concretes with addition of clinoptilolite from Beli Plast deposit (Bulgaria), silica fume and fly ash

Clay Minerals ◽  
2011 ◽  
Vol 46 (2) ◽  
pp. 213-223 ◽  
Author(s):  
V. Lilkov ◽  
I. Rostovsky ◽  
O. Petrov
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Mechanical Characteristics ◽  
Physical And Mechanical Properties ◽  
Specific Pore Volume ◽  
Cement Mortars ◽  
Physical And Mechanical Characteristics

AbstractCement mortars and concretes incorporating clinoptilolite, silica fume and fly ash were investigated for changes in their physical and mechanical properties. It was found that additions of 10% clinoptilolite and 10% Pozzolite (1:1 mixture of silica fume and fly ash) were optimal for improvement of the quality of the hardened products, giving 8% and 13% increases in flexural and compressive strength respectively. The specific pore volume of the mortars incorporating zeolite decreased between the 28th and 180th day to levels below the values for the control composition due to the fact that clinoptilolite exhibits its pozzolanic activity later in the hydration. In these later stages, pores with radii below 500 nm increased at the expense of larger pores. The change in the pore-size distribution between the first and sixth months of hydration occurs mostly in the mortars with added zeolite.

scholarly journals Numerical and Experimental Investigation on Radiated Noise Characteristics of the Multistage Centrifugal Pump

Processes ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 793 ◽  
Author(s):  
Si ◽  
Wang ◽  
Yuan ◽  
Huang ◽  
Lin ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Noise Source ◽  
Low Noise ◽  
Pressure Level ◽  
Radiated Noise ◽  
Noise Characteristics ◽  
Flow Induced Noise ◽  
Multistage Pump

The radiated noise of the centrifugal pump acts as a disturbance in many applications. The radiated noise is closely related to the hydraulic design. The hydraulic parameters in the multistage pump are complex and the flow interaction among different stages is very strong, which in turn causes vibration and noise problems because of the strong hydraulic excitation. Hence, the mechanism of radiated noise and its relationship with hydraulics must be studied clearly. In order to find the regular pattern of the radiated noise at different operational conditions, a hybrid numerical method was proposed to obtain the flow-induced noise source based on Lighthill acoustic analogy theory, which divided the computational process into two parts: computational fluid dynamics (CFD) and computational acoustics (CA). The unsteady flow field was solved by detached eddy simulation using the commercial CFD code. The detailed flow information near the surface of the vane diffusers and the calculated flow-induced noise source was extracted as the hydraulic exciting force, both of which were used as acoustic sources for radiated noise simulation. The acoustic simulation employed the finite element method code to get the sound pressure level (SPL), frequency response, directivity, et al. results. The experiment was performed inside a semi-anechoic room with a closed type pump test rig. The pump performance and acoustic parameters of the multistage pump at different flow rates were gathered to verify the numerical methods. The computational and experimental results both reveal that the radiated noise exhibits a typical dipole characteristic behavior and its directivity varies with the flowrate. In addition, the sound pressure level (SPL) of the radiated noise fluctuates with the increment of the flow rate and the lowest SPL is generated at 0.8Qd, which corresponds to the maximum efficiency working conditions. Furthermore, the experiment detects that the sound pressure level of the radiated noise in the multistage pump rises linearly with the increase of the rotational speed. Finally, an example of a low noise pump design is processed based on the obtained noise characteristics.

scholarly journals Waterproofing material for protection of underground structures

2019 ◽  
Vol 97 ◽  
pp. 02008
Author(s):  
Olga Lyapidevskaya
Keyword(s):  
Crack Resistance ◽  
Mechanical Characteristics ◽  
Physical And Mechanical Properties ◽  
Ethylene Vinyl Acetate ◽  
Hard Coatings ◽  
Optimal Composition ◽  
Underground Structures ◽  
High Elasticity ◽  
Main Disadvantage ◽  
Physical And Mechanical Characteristics

The article deals with the problem of increasing the durability of underground and buried buildings. One of the methods of solving this problem is ensuring the reliable protection of underground structures from the effects of water of different origin. Among the existing waterproofing coatings, mineral-based compositions are the most effective. However, the main disadvantage of such systems is the low crack resistance of hard coatings, which limits their applicability. We have made an attempt to develop a cement-based waterproofing material that would have high elasticity, strength, crack resistance and adhesion to a concrete base. We have conducted studies to justify the possibility of obtaining an effective waterproofing material by including microsilica and ethylene vinyl acetate in the mix. The optimal composition of the material was worked out. On the basis of the experimental data, the main physical and mechanical properties of the material were established. Based on the obtained results, it was found that the resulting material had high physical and mechanical characteristics and could be recommended for the protection of concrete structures used in underground construction.

scholarly journals Error estimation of the physical and mechanical characteristics measurements by indentation

2018 ◽  
Vol 9 (3) ◽  
pp. 263-271
Author(s):  
A. P. Kren ◽  
O. V. Matsulevich ◽  
M. N. Delendik
Keyword(s):  
Measurement Error ◽  
Error Estimation ◽  
Evaluation System ◽  
Mechanical Characteristics ◽  
Physical And Mechanical Properties ◽  
Strain Hardening Exponent ◽  
Indirect Measurements ◽  
Static Indentation ◽  
Indentation Methods ◽  
Physical And Mechanical Characteristics

The active application in the practice of testing the indentation methods, in particular to measure the physical and mechanical properties of metals, polymers, biological technologies demands to development techniques for the measurement error estimation. At the same time existing traditional measurement error evaluation system, based on the using of the reference blocks, is not always suitable for use in testing and research laboratories. The aim of this work was development the technique for estimating the indirect measurements error of materials physical and mechanical characteristics that can be applied in practice and based on the existing standards. Checking of the proposed approach using the experimental values of the hardness and elastic modulus obtained during static indentation for various metals.It is shown that since the initial information about the material is an indentation curve representing the dependence of the load versus penetration depth of the indenter into the material tested, then it is better to confirm the metrological characteristics of the indentation measuring devices using the applied force and achieved displacement, but to estimate the accuracy of determining the properties through the error of indirect measurements. The equations for calculating the hardness and modulus of elasticity are derived. It allows to determine the component value most influencing the error magnitude. The calculation of error on the base of the value of boundary of a random and non-exclusive systematic error was carrying out.The advantage of the developed technique is the fact that the measurement of the physical and mechanical characteristics is based on the experimental data and does not require the creation of the additional metrological assurance. The proposed approach seems appropriate to extend for the determination of the measurement error of other characteristics: the yield point, the strain hardening exponent, creep, relaxation, determined by the indentation methods.

scholarly journals Basic physical and mechanical characteristics of ice based on the results of the expedition “Transarktika-2019”

2020 ◽  
Vol 66 (3) ◽  
pp. 293-320
Author(s):  
S. M. Kovalev ◽  
V. A. Borodkin ◽  
N. V. Kolabutin ◽  
A. A. Nubom ◽  
Ev. V. Shimanchuk ◽  
...  
Keyword(s):  
Sea Ice ◽  
Uniaxial Compression ◽  
Mechanical Characteristics ◽  
Lower Boundary ◽  
Physical And Mechanical Properties ◽  
Average Density ◽  
Current Season ◽  
Ice Surface ◽  
Second Year ◽  
Physical And Mechanical Characteristics

On the “Transarktika-2019” expedition, works were carried out for determining the physical and mechanical characteristics of frost field of the first-year sea ice and the field of second-year ice. The thickness of the ice cover was determined by contact and non-contact methods, the temperature, salinity and density of ice, the strength of the samples at central bending and uniaxial compression, as well as the local (borehole) strength of ice were measured. Studies have shown that most of the field is an ice formation formed in the process of dynamic metamorphism. At the beginning of the expedition, an ice floe passed through a section of warm surface waters. This led to the disappearance of the openwork layer on the lower boundary of the ice and stopping the growth of ice from below. During the observation period, the average temperature and salinity of the deformed ice increased, while the average density decreased. The values of mechanical characteristics decreased with increasing temperature and brine volume. The average borehole strength were close to the values obtained by the quadratic approximation for ice in the area of the Ice Station “Cape of Baranov”. The physical and mechanical properties of the level ice are generally similar to the properties of ice, composed mainly of fibrous structures. The ratios between the borehole strength and the strength under uniaxial compression of ice samples drilled parallel to the ice surface were 4.5 and 4.7, which corresponds to the literature data. The thickness of the second-year sea ice at the place of work was 166 — 169 cm, the snow height was 27 cm, the raft of the ice surface above the water surface was 15 cm. The average ice temperature was –4.0 °C. Second-year ice can be divided into three parts that differ in their physical properties. The upper part (0 — 10 cm) was formed in the autumn. The second part (10 — 85 cm) is ice that has undergone seasonal thermometamorphic changes. The lower part was formed during the natural growth of ice from below at the current season.

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