APLIKASI HELMHOLTZ RESONATOR DENGAN VARIASI JUMLAH MONONECK DALAM ARAH LONGITUDINAL PADA INLET MANIFOLD MOTOR DIESEL SUPERCHARGING 4 TAK

Penelitian ini bertujuan untuk mengetahui pengaruh Circular Helmholtz Resonator dengan variasi jumlah Mononec pipa kapiler terhadap Supercharging yang digerakan elektromotor. Penelitian eksperimenal ini dilakukan dengan 6 variasi Mononeck yang dipasang secara longitudinal up side down. Piezotronics, National Instrument dan Matlab digunakan untuk mengakuisisi data menjadi lebih akurat. Hasil pengukuran selisih rata-rata tekanan output dan input menyatakan bahwa Circular Helmholtz Resonator berpengaruh terhadap tekanan udara keluaran yang merupakan tekana udara input motor diesel.

Cycle-skipping strategy with intake air cut off for natural gas fueled Si engine

In this study, cycle-skipping was investigated for a natural gas engine which has single cylinder, unsupercharged with 1.16 L volume and spark ignition. Additionally, inlet manifold air was switched off during cycle-skipping to minimize pumping losses. Thus, cycle-skipping strategy was carried out, and its effects on emission and engine performance were investigated. Indicated mean effective pressure, indicated efficiency, specific emissions (CO, HC, and NOX) and combustion characteristics (in-cylinder pressure and rate of heat release) were investigated in the study. As a result of performed study, it is predicted that a significant improvement can be achieved in indicated thermal efficiency as 22.8% and 13.4% by different cycle-skipping strategies. However, there is not a continuous change in emissions for different cycle-skipping strategies. While CO and NOX emissions increased in 3N1S (three normal, one cycle-skip) condition, HC emissions decreased in accordance with normal condition. For both cycle-skipping strategies, all the emissions have an increase in accordance with normal condition. In 3N1S and 2N1S (two normal, one cycle-skip) cycle skip engine operating conditions, compared to engine operating under normal condition, CO emissions increased by 14.7 and 51.7 times, respectively. In terms of HC emissions, while emission values decreased by 27.8% under 3N1S operating conditions, they increased by 67.2% under 2N1S operating conditions. Finally, in 3N1S and 2N1S cycle skip engine operating conditions, NOx emissions increased by 3.7 and 6.9 times, respectively, compared to normal operating condition. Another significant result of this study is that peak in-cylinder pressure increased as the cycle-skipping rate increased.

IMPROVING MARINE DIESEL ENGINE ENVIRONMENTAL PERFORMANCE BY CARBURATION OF DIMETHYL ETHER IN INLET MANIFOLD

The article highlights the measures to be introduced in order to restrict the hazardous emissions from the marine vessels as a result of increasing attention of the global community to the air pollution problem. The most difficult for ship owners is to adhere to the requirements of MARPOL 73/78 in NECA Tier III. As a result of the analysis of modern widely used methods for reducing harmful emissions of nitrogen oxides from a marine ICE there have been determined the main advantages and disadvantages of these methods. A new method including the additional component supply system, which delivers additional component to an inlet manifold of a marine ICE, and the most suitable additional component were proposed. Main advantages of the proposed system over other systems were determined. The system operation diagram is presented and the academic novelty of the scientific work was determined. The academic novelty consists in using an adapted mathematical model for calculating the main parameters of the system developed. At the current stage of the work, the development of an electronic control unit for the system and additional electronic control unit is in progress. The next stage of the work consists of calculating the main parameters of the system and testing the system in various operating modes of marine diesel engine 3NVD 24

Studi Eksperimental Pengaruh Variasi Diameter Tabung Ear Resonator terhadap Tekanan Aliran Udara Supercharging pada Inlet Manifold

<p><strong>Abstrak</strong></p><p><strong> </strong></p><p>Supercharger dan resonator merupakan salah satu komponen penting menyangkut tekanan udara pada langkah pembakaran dalam motor diesel 4 tak. Penelitian ini bertujuan untuk mengetahui pengaruh diameter tabung Ear Resonator terhadap tekanan aliran udara Supercharging pada Inlet Manifold. Metode eksperimental digunakan dalam penelitian dengan memvariasikan diameter tabung sebanyak 5 buah Ear Resonator yaitu ½”, ¾”, 1”, 11/4”, dan 1½” yang dipasang secara horizontal. Hasil olahan selisih rata-rata tekanan input dan output menyatakan bahwa variasi diameter tabung Ear Resonator berpengaruh terhadap tekanan yaitu: Variasi ke-2 merupakan tekanan output tertinggi dengan nilai sebesar 101359.90 N/m2 atau dengan beda tekanan output dan input dengan nilai sebesar -64.92 N/m2 atau sebesar -0.06 %. Variasi ke-5 merupakan salah satu tekanan output terendah dengan nilai sebesar 101325.04 N/m2 atau dengan beda tekanan output dan input tertinggi dengan nilai sebesar 23.31 N/m2 atau sebesar 0.02 %.</p>

Turbo-Сompressors: Working Peculiarities, Causes of Failures

Рассмотрены вопросы использования турбокомпрессоров (ТРК), производителей ТРК, принцип работы, пути совершенствования, причины отказов. Работу ТРК совершенствуют инженеры во всём мире, при этом основная задача заключается в том, чтобы продлить срок эксплуатации и увеличить эффективность ТРК. Принцип работы ТРК заключается в том, что энергию на вращение вала ТРК получает от отработанных газов, воздействующих на горячую улитку, расположенную на одном валу с холодной улиткой, которая нагнетает воздух во впускной коллектор. ТРК совершенствуют следующими путями: уменьшают размеры и увеличивают скорость вращения вала ТРК; добавляют управление (электронное, механическое) перепускным клапаном давления; используют турбину с регулируемым сечением и ротором, который содержит дополнительные подвижные лопатки, регулирующие поток отработанных газов на низких и на высоких оборотах двигателя; используют параллельную установку ТРК, применяют сдвоенные ТРК, турбокомпаунд; используют современные материалы – керамику. При работе двигателя внутреннего сгорания ТРК выходят из строя. Рассмотрены неисправные узлы, проведён анализ причин выхода из строя турбин и разработан ряд мероприятий, придерживаясь которых можно продлить срок службы ТРК или выработать тот срок службы, который был заложен заводом-изготовителем. К основным причинам выхода из строя ТРК можно отнести следующие: недостаток масла, попадание посторонних предметов в ТРК, загрязнённое масло, попадание абразива через воздушный фильтр. Для устранения указанных причин рекомендуется выполнять своевременную замену масла с масляным фильтром; выполнять своевременную замену воздушного фильтра; использовать только качественное масло, соответствующее виду топлива и рекомендованное для турбин; использовать турботаймер или после поездки выключать двигатель транспортного средства не сразу, а дав поработать ему на холостых оборотах, чтобы охладилась турбина и снизилось число оборотов вращения вала ТРК. The issues of use of turbo-compressors (TC), manufacturers of TC, operation principle, ways of improvement, causes of failures are considered. The work of the TC is being improved by engineers around the world, the main task being to extend the service life of the TC and increase the efficiency of the TC. The principle of the TC operation is that the energy for rotation of the TC shaft is received from the exhaust gases acting on the hot volute located on the same shaft as the cold volute, which pumps air into the inlet manifold. TC is improved in the following ways: reduce the size and increase the rotation speed of the TC shaft; add control (electronic, mechanical) of the pressure relief valve; use a turbine with a variable area and a rotor, which includes additional movable vanes that control the flow of exhaust gases at low and high engine speeds; use a parallel TC installation, use dual TC, a turbocompound; use modern materials – ceramics. During operation of the internal combustion engine the TC fails. The faulty units were considered, the causes of turbine failure were analyzed and a number of measures were developed, adhering to which it is possible to extend the service life of the TC or develop the service life that was laid down by the manufacturer. The main reasons for the failure of the TC include the following: lack of oil, ingress of foreign objects into the TC, contaminated oil, ingress of abrasive material through the air filter. To eliminate these reasons, it is recommended to perform timely replacement of oil with oil filter; perform timely replacement of air filter; use only the quality oil corresponding to the type of fuel and recommended for turbines; use a turbo timer or after the trip turn off the vehicle engine not immediately, but by letting it work at idle speed so that the turbine cools and the rate speed of the TC shaft rotation decreases.

Effect of aspect ratio and inlet manifold shape on the laminar-to-turbulent transition of gas flow in rectangular microchannels

A combined experimental and numerical study on the laminar-to-turbulent transition in microchannels using gas flow is presented. The effects of two geometric parameters, namely aspect ratio (height to width) of microchannels and inlet manifold shape, are considered on the value assumed by the critical Reynolds number linked to the laminar-to-turbulent transition. To study the effect of aspect ratio, seven rectangular microchannels having an aspect ratio between 0.25 and 1.04 are micro-milled in PMMA plastic with a constant length of 100 mm. Four rectangular microchannels with different inlet shapes, namely sudden contraction, rounded entrance, V shape and bellmouth, are fabricated to analyze the effects of inlet shape. Pressure loss analyses are then performed for all 11 microchannels by evaluating both average and semi-local friction factors. The Reynolds number in correspondence of which the transition takes place is determined by observing the trend of the friction factor. In parallel, numerical simulations using an intermittency-based transitional turbulence model are also performed and results are compared with the experiments. Experimental and numerical results have demonstrated that both of the investigated geometrical characteristics (aspect ratio and inlet manifold shape) play an important role on the range of the Reynolds number between the onset of transition and the onset of fully turbulent regime for gas microflows. Experimental critical Reynolds numbers show a good agreement with the predictions of the conventional theory and are in the range of 1863–3470 for all the tested microchannels. The role of gas compressibility on the laminar-to-turbulent transition is also discussed. Graphic abstract