UDC 621.43(574) DOI 10.52167/1609-1817-2023-124-1-75-84
A.B. Kukesheva1 , A.S. Kadyrov1, Sh. M. Suyunbaev2. K.A. Sinelnikov1, Pak I.A.1
1Abylkas Saginov Karaganda Technical University NPJSC, Karaganda, Kazakhstan
2Tashkent state transport university, Tashkent, Uzbekistan E-mail: [email protected]
DEVELOPMENT OF A METHODOLOGY FOR EXPERIMENTAL STUDIES TO DETERMINE THE OPTIMAL OPERATING MODES OF AN ULTRASONIC
MUFFLER
Abstract. The article considers the urgent issue of reducing the toxicity of harmful components of car exhaust gases. In order to solve this problem, a direction was proposed to improve the system for cleaning exhaust gases of internal combustion engines by introducing an ultrasonic emitter into the muffler device. An experimental installation of a muffler with an ultrasonic emitter was made The experimental plan for determining the effectiveness of the ultrasonic muffler based on the method of similarity theory and dimensional analysis was made.
Dimensionless criteria have been obtained that make it possible to determine the optimal operating modes of the ultrasonic muffler.
Keywords. Internal combustion engine, automobile muffler, exhaust gases, ultrasonic coagulation, similarity theory and dimensional analysis, dimensionless criterion, experimental plan.
Introduction.
Nowadays, automobile transport has become an integral part of daily human life, exerting its positive as well as negative influence. For example, cars equipped with internal combustion engines consume huge amounts of engine fuel and emit harmful substances into the environment together with exhaust gases. This problem is especially acute in large cities and near highways.
After all, cars account for 80-90% of atmospheric pollution in large cities, which greatly exceeds the share of industrial enterprises [1].
The exhaust gases of internal combustion engines contain about 200 different components, most of which are toxic. And the release of toxic substances occurs at the level where a person breathes in the air. The total period of existence of toxic gases in the air lasts from 2-3 minutes to 4-5 years, thereby having a continuous harmful effect on the environment and human health [2].
Improving the emission of harmful exhaust gases can be achieved through the adoption of design solutions aimed at improving the environmental friendliness of vehicles. One of the design solutions is further improvement of the gas cleaning system in internal combustion engines. Improvement of the gas purification system is achieved by introducing more advanced purification methods into the operation of the muffler, which include ultrasonic cleaning.
It was found that the elastic vibrations of ultrasonic frequency can cause changes in the media in which they propagate. For example, when ultrasonic elastic oscillations propagate in a gas medium, the intensity of coagulation process in gas impurities increases, which leads to an increase in its degree of purification from harmful particles. Coagulation refers to the process of convergence and enlargement of small solid particles suspended in the gas under the influence of acoustic vibrations of ultrasonic frequencies [3]. The effectiveness of ultrasonic frequency oscillations is so high that it allows to obtain a high rate of exhaust gas purification, which is not achievable with other cleaning methods. Moreover, application of ultrasound allows influencing more aggressive gas impurities due to intensification of coagulation process and also makes
possible its introduction into the muffler device due to compact size of ultrasonic emitters.
Consequently, the use of ultrasonic method of cleaning to improve the efficiency of automotive muffler is an urgent task [4].
Materials and methods.
The scientific group of the Department of Transport Engineering and Logistics Systems of the Karaganda Technical University has developed an experimental ultrasonic installation to establish parameters affect the operation mode of an automobile muffler for ultrasonic cleaning of exhaust gas.
The experimental ultrasonic installation (figure 1) consists of a body of the installation 6 (steel pipe), an inlet 1 branch pipe with a flange 3 and an outlet 9 branch pipe, an ultrasonic emitter of the longitudinal and transverse directions 5 and an ultrasonic generator 7.
1 - exhaust gas inlet pipe, 2 - bolt, 3 - flange, 4 - nut, 5 - ultrasonic emitter, 6 - unit body (steel pipe), 7 - ultrasonic generator, 8 - ultrasonic area, 9 - exhaust gas outlet pipe.
Figure 1 - Scheme of the experimental installation of an ultrasonic muffler
For experimental studies, the installation is connected to a passenger car through the inlet pipe 1 with a rubber hose supplying exhaust gases. Inside the installation, when the ultrasonic generator is turned on, longitudinal ultrasonic waves act on the exhaust gas. Ultrasonic intensification of coagulation and coalescence processes takes place in the installation.
Ultrasonic intensification of coagulation and coalescence processes takes place in the installation. As a result, the exhaust gases are cleaned due to the sedimentation of coarse particles of the exhaust gas at the bottom of the installation, and the purified exhaust gas is discharged through the outlet pipe 9, (figure 2).
Figure 2 – Exhaust gas cleaning process under the influence of ultrasound
During the experiment, measurements of the composition of the exhaust gases without exposure and with exposure to a longitudinal ultrasonic wave, depending on the engine crankshaft rotation range, in order to determine the optimal modes of operation of the ultrasonic muffler. The operating modes of an ultrasonic muffler are a set of its processes of transition from one state to another, determined by a large number of its parameters. The parameters of the
ultrasonic muffler should be selected so that it is possible to set the optimal modes of its operation, while maintaining its high level of exhaust gas purification.
Parameters, influencing operation mode of ultrasonic muffler are integral elements of experimental investigations, without which it is impossible to plan the experiment, conduct experiments and perform processing of obtained results. In order to set up and process the experiments correctly, it is necessary to go into the essence of ultrasonic muffler operation process, give general qualitative analysis of parameters characterizing the process and represent them in a dimensionless form. In setting up experiments, it is very important to obtain the correct dimensionless parameters, the number of which should be minimal [5]. However, the operation of an ultrasonic muffler depends on a significant number of parameters (variables), such as engine speed, ultrasonic frequency, gasoline mass, oxygen mass, gas density, ultrasonic muffler pipe diameter, dynamic gas viscosity, gas particle velocity, and many others. The possibility of preliminary qualitative-theoretical analysis in order to reduce the set of variables and to choose the system of defining dimensionless parameters gives the method of similarity theory and dimensional analysis. This method can be applied to the consideration of very complex processes and greatly facilitates the processing of experiments with a large number of variables, thereby reducing the number of experiments, saving time and money for its implementation [6].
In accordance with the provisions of the method of similarity theory and dimensional analysis we considered the following fundamental variables, which will help to experimentally determine the optimal operating modes of the ultrasonic muffler: engine speed ( ), ultrasonic frequency ( ), gasoline mass ( ), oxygen mass ( ), gas density ( ), ultrasonic muffler pipe diameter ( ), dynamic gas viscosity ( ), and gas particle velocity ( ). As a result, we obtained eight fundamental variables that depend on oxygen mass, the functional relation of which can be written in the following form, formula (1):
(1)
From this follows the following equation, formula (1.2):
(2)
Then we transform the obtained variables, expressing their dimension in relation to three main units of measurement: length L, mass M and time T, (table 1).
Table 1 - List of dimension formulas for the main quantities of variables
№ Variable name Designation Unit of measure Dimensionality formula
1 Engine speed c-1 T-1
2 Ultrasonic frequency c-1 T-1
3 Gas density kg/m3 ML-3
4 Ultrasonic muffler pipe diameter m L
5 Dynamic gas viscosity Ра с ML-1 T-1
6 Gas particle velocity m/с ML-1
7 Gasoline mass kg M
8 Oxygen mass kg M
Let us assume that the number of basic dimensionless parameters, through which all variables can be expressed, is equal to . According to the resulting equation (formula 2) the number of variables is and the number of basic units is , in accordance with π-
theorem the number of basic dimensionless parameters will be: . Consequently, we obtain the following equation, formula (3):
(3)
This implies the following equation, formula (4): (4)
where are dimensionless parameters, which are found in the following way. From among variables, we choose three with independent dimensions, including three basic units (length , mass and time ), let it be ultrasonic muffler pipe diameter , gas particle velocity (ϑ) and gas density (ρ) . Now let's define the dimensionless parameters . The selected three variables ( ) will be included in each of the -terms, the remaining variables, one by one, will be included in the previously formed -members. The exponent of the three main variables determining the dimensionless parameters are unknown, hence we denote them by . We take the exponent of the other variables will be taken equal to -1. As a result, the relations for -members will have the following formulas (5), (6), (7). (8): (5)
(6)
(7)
(8)
The variables included in the terms can be expressed in terms of the principal dimensions. Since these terms are dimensionless, the exponent of each of the principal dimensions should be equal to zero. The solution of the resulting system of equations makes it possible to find the numerical values of the unknown exponents of degree . As a result, each of the -members is defined in the form of a formula composed of specific values in the corresponding degree. Then we compose the dimension equation for the first term , formula (9) (9)
We add up the exponents of the degree with the same base, formula (10) (10)
In order for the dimension of to be equal to one, it is necessary to equate all exponents to zero, formula (11). (11)
The system of algebraic equations (formula 11) contains three unknown quantities
Substituting these exponent values into the first term , we obtain the first dimensionless parameter, formula (12):
(12) We carry out a similar calculation for the remaining π-terms and, accordingly, obtain the second, third and fourth dimensionless parameters, formulas (13), (14), (15):
(13)
(14)
(15)
Substituting the resulting -terms into equation (1.4), we obtain four dimensionless parameters, formula (16):
. (16)
We solve the equation for , where we derive on the left side of the equation. Taking into account the proportionality between the parameters , we express the third term by the Reynolds criterion . Then we reduce the dimensionless parameters of the first and second -members to each other and obtain a single criterion. Thus, we can now write the previous equation (formula (16) in the following form, formula (17):
(17)
Thus, our chosen fundamental variables were reduced to dimensionless parameters and transformed into three similarity criteria, formulas (18), (19), (20).
; (18)
; (19)
(20)
The obtained similarity criteria theoretically describe the operation of the ultrasonic muffler. The criterion in the form of characterizes the efficiency of fuel consumption, i.e. the completeness of its combustion. However, the criterion , although it makes it possible to evaluate the efficiency of fuel combustion, but does not allow us to compare the output parameters describing the operation mode of the muffler with and without exposure to the ultrasonic emitter. In addition, the excess air ratio λ is assumed to be the criterion characterizing the effective combustion of fuel.
Excess air coefficient is a dimensionless value representing the ratio of the mass of air entering the engine cylinder to the mass of air theoretically necessary for complete combustion
of the fuel fed into the cylinder, calculated by analyzing the composition of exhaust gases of vehicles. The analysis of the composition of vehicle exhaust gases is carried out by devices during the maintenance of vehicles. Such analysis can be carried out with the gas analyzer BEA055, designed to assess the efficiency of fuel combustion and evaluate the smokiness of the exhaust gas. This device measures the following parameters, (figure 2).
As follows from the table, the results of measurements of the composition of exhaust gases of cars, namely carbon monoxide (CO), hydrocarbon (HC) carbon dioxide (CO2), oxygen (O2) are shown as a percentage of their total volume, (table 2).
Table 2 – Range and measurement error using the Bosh BEA 050 gas analyzer module
Indicator Measuring range Error
СО 0-10% 0.001%
НС 0-9999 ppm 1 ppm
СО2 0-18% 0.01%
О2 0-22% 0.01%
Excess air coefficient 0,500-9,999 0,001
Figure 3 – Bosh BEA 050 Gas analyzer module
In case of determining the optimal operating mode of the ultrasonic muffler, the criterion of its effectiveness is the best cleaning of the exhaust gas, i.e. increase in the oxygen content in relation to other gases. Increase of oxygen can occur due to coagulation of heavy particles of the exhaust gas and reduction of their volume due to sedimentation. As studies show, an increase in the percentage of oxygen occurs during ultrasonic exposure, followed by the splitting of CO and CO2 molecules. However, the following contradiction arises: for good combustion of the fuel, the amount of oxygen in the muffler should tend to decrease, but at the same time, to clean the exhaust gas, the amount of oxygen should increase.
This contradiction occurs due to the fact that the excess air coefficient and the percentage ratio of gases are usually measured before they enter the muffler. In case of measuring these parameters after the impact on gases by an ultrasonic muffler, the value of will be determined by the approximate ratio of the mass of combusted fuel to the mass of air in the muffler. Thus, criterion can be converted to the ratio of the total sum of gases to oxygen.
Indeed, the mass in criterion is equated with the mass of gases, then we can consider, formula (21):
. (21)
However, this criterion works to evaluate the performance of a single muffler. For our
without exposure to an ultrasonic emitter. The ratio of the criteria of the muffler operation without ultrasound to the same criterion with ultrasound operation, formula (22):
(22)
gives us the ratio of the percentage of oxygen when the muffler operates without ultrasound and with ultrasound, subject to the standard value λ.
Results and discussion.
Based on the criteria obtained, the goal of experimental studies was established, which is to determine the optimal operating modes of the ultrasonic muffler with and without exposure to gases by an ultrasonic emitter, depending on the engine speed. Experimental studies will be conducted on the previously developed experimental setup of the ultrasonic muffler, (figure 4).
Figure 4 – Experimental installation of ultrasonic muffler
According to the purpose of the experiment, the optimal operating modes of the ultrasonic muffler will be determined in different ranges of the engine crankshaft speed, varied by the ultrasonic wave frequency from 0 to 45 kHz, the ratios of which can be represented as the criterion. Based on the results of the experiments, the values for the composition of the exhaust gases are determined, as well as the percentage of air released from the muffler with and without the influence of ultrasound on them. The ratios of these parameters correspond to the criteria .. Numerical values, which will ultimately help to establish the optimal operating modes of the ultrasonic muffler. The experiment will be conducted at the set value of Reynolds number . Thus, the criteria obtained by the method of similarity theory and dimensional analysis allows us to make a plan for the experiment.
The first stage of experiment planning involves varying the criteria at two levels, the interval of variation of which corresponds to a scale from +1 (the upper level) to -1 (the lower level). If the number of criteria is known and they are varied at two levels, it is possible to find the number of experiments required to realize all possible combinations of factor levels. In this case, an experiment in which all possible combinations of factor levels are implemented is called a full factorial experiment. As a result, the experimental plan has eight experiments and corresponds to the full multifactorial plan of experiment 23. The conditions of the full multivariate plan of experiment 23 can be written in the form of a matrix, where the rows correspond to different experiments, and the columns correspond to the values of the factors. In this connection the matrix of the plan of experiment has the following form, (table 3):
Table 3 – Matrix 23 experiment plan
Experiment numbers x1 x2 x3 У
1 -1 -1 +1 y1
2 -1 +1 -1 y2
3 +1 -1 -1 y3
4 +1 +1 +1 y4
5 -1 -1 -1 y5
6 -1 +1 +1 y6
7 +1 -1 +1 y7
8 +1 +1 -1 y8
According to the obtained matrix, it is possible to give a geometric interpretation of the full factorial experiment 23. The geometric interpretation of the full factorial experiment 23 is a cube, the coordinates of the vertices of which are set by the conditions of the experiments, (figure 5). The cube defines the area of the experiment, and the center of the cube is its center.
To construct a graphic representation of the plan, it is necessary to determine the average, maximum, and minimum values of the criteria corresponding to the cube coordinates.
Figure 5 – Geometric interpretation of the full factor experiment 23
The result of processing the experiment should be a regression equation of the form, formula (23):
(23)
where a,b,c and d are regression coefficients.
Subsequent analysis of equation allows us to determine by solving the minimax problem of the optimal parameter of gas purification mode.
Conclusion.
Thus, the experimental plan obtained allows to confirm the effectiveness of the application of the ultrasonic coagulation method on the developed installation and to determine the optimal operating modes of the ultrasonic muffler. The optimal operating modes of the ultrasonic muffler will be established in the course of experimental studies, depending on the obtained indicators for the composition of gas and oxygen, as well as on the criteria k1, k2, k3, which were formed using the similarity theory method and dimensional analysis, which allowed
draw up an experiment plan, but also to increase the efficiency of processing experimental data on the experimental setup of an ultrasonic muffler.
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Алия Кукешева, докторант, Әбілқас Сағынов атындағы Қарағанды техникалық университеті, Қарағанды, Қазақстан, [email protected]
Адиль Кадыров, т.ғ.д., профессор, Әбілқас Сағынов атындағы Қарағанды техникалық университеті, Қарағанды, Қазақстан, [email protected]
Шинболат Суюнбаев, т.ғ.к., профессор, Ташкент мемлекеттік көлік университеті, Ташкент, Өзбекстан, [email protected]
Кирилл Синельников, докторант, Әбілқас Сағынов атындағы Қарағанды техникалық университеті, Қарағанды, Қазақстан, [email protected]
Игорь Пак, PhD, Әбілқас Сағынов атындағы Қарағанды техникалық университеті, Қарағанды, Қазақстан, [email protected]
УЛЬТРАДЫБЫСТЫҚ БӘСЕҢДЕТКІШТІҢ ОҢТАЙЛЫ ЖҰМЫС РЕЖИМДЕРІН АНЫҚТАУ БОЙЫНША ЭКСПЕРИМЕНТТІК ЗЕРТТЕУ ӘДІСТЕМЕСІН ӘЗІРЛЕУ
Аңдатпа. Мақалада автокөліктің пайдаланылған газдарының зиянды құрауыштарының уыттылығын төмендетудің өзекті мәселесі қарастырылған. Осы мәселені шешу мақсатында іштен жану қозғалтқыштарының пайдаланылған газдарын тазарту жүйесін жетілдіру бойынша бағыт, яғни автокөлік бәсеңдеткішінің құрылғысына ультрадыбыстық сәулелендіргішті енгізу ұсынылды. Ультрадыбыстық сәулелендіргіші бар бәсеңдеткіштің эксперименттік қондырғысы жасалды. Ультрадыбыстық бәсеңдеткіштің тиімділігін анықтау үшін ұқсастық теориясы әдісі мен өлшемділікті талдау әдісінің негізінде эксперимент жоспары жасалды. Ультрадыбыстық бәсеңдеткіштің оңтайлы жұмыс режимдерін анықтауға мүмкіндік беретін өлшемсіз критерийлер алынды.
Түйінді сөздер. Іштен жану қозғалтқышы, автокөлік бәсеңдеткіші, пайдаланылған газдар, ультрадыбыстық коагуляция, ұқсастық теориясы және өлшемділік талдауы, өлшемсіз критерий, эксперимент жоспары.
Алия Кукешева, докторант, Карагандинский технический университет имени Абылкаса Сагинова, Караганда, Казахстан, [email protected]
Адиль Кадыров, д.т.н., профессор, Карагандинский технический университет имени Абылкаса Сагинова, Караганда, Казахстан, [email protected]
Шинболат Суюнбаев, к.т.н., профессор, Ташкентский государственный транспортный университет, Ташкент, Узбекистан, [email protected]
Кирилл Синельников, докторант, Карагандинский технический университет имени Абылкаса Сагинова, Караганда, Казахстан, [email protected]
Игорь Пак, PhD, Карагандинский технический университет имени Абылкаса Сагинова, Караганда, Казахстан, [email protected]
РАЗРАБОТКА МЕТОДИКИ ЭКСПЕРИМЕНТАЛЬНЫХ ИССЛЕДОВАНИЙ ПО ОПРЕДЕЛЕНИЮ ОПТИМАЛЬНЫХ РЕЖИМОВ РАБОТЫ УЛЬТРАЗВУКОВОГО
ГЛУШИТЕЛЯ
Аннотация. В статье рассмотрен актуальный вопрос по снижению токсичности вредных компонентов отработавших газов автомобиля. С целью решения этой проблемы предложено направление по усовершенствованию системы очистки отработавших газов двигателей внутреннего сгорания, посредством внеднения в устройство глушителя ультразвукового излучателя. Изготовлена экспериментальная установка глушителя с ультразвуковым излучателем. Составлен план эксперимента для определения эффективности работы ультразвукового глушителя на основе метода теории подобия и анализа размерностей. Получены безразмерные критерии, которые позволяют определить оптимальные режимы работы ультразвукового глушителя.
Ключевые слова. Двигатель внутрененго сгорания, автомобильный глушитель, отработавшие газы, ультразвуковая коагуляция, теория подобия и анализ размерностей, безразмерный критерий, план эксперимента.
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