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Keywords = combustion-powered actuation

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20 pages, 6824 KiB  
Article
Basic Study on Operation Control Systems of Internal Combustion Engines in Hybrid Small Race Cars to Improve Dynamic Performance
by Hayato Yamada, Masamune Kobayashi, Yusuke Ebashi, Shinobu Kasamatsu, Ikkei Kobayashi, Jumpei Kuroda, Daigo Uchino, Kazuki Ogawa, Keigo Ikeda, Taro Kato, Xiaojun Liu, Ayato Endo, Mohamad Heerwan Bin Peeie, Takayoshi Narita and Hideaki Kato
Vehicles 2025, 7(2), 41; https://doi.org/10.3390/vehicles7020041 - 30 Apr 2025
Viewed by 545
Abstract
Hybrid vehicles utilize multiple power sources, making them energy-efficient and enhancing both fuel efficiency and dynamic performance. As a result, hybrid vehicles have recently been adopted as race cars, which demand high powertrain performance. The hybrid vehicle system comprises two power sources: an [...] Read more.
Hybrid vehicles utilize multiple power sources, making them energy-efficient and enhancing both fuel efficiency and dynamic performance. As a result, hybrid vehicles have recently been adopted as race cars, which demand high powertrain performance. The hybrid vehicle system comprises two power sources: an internal combustion engine (ICE) and an electric motor, both of which require precise control. Controlling the output of the internal combustion engine is particularly challenging. This study investigated the dynamic response of an actuator in an electronic throttle system. The experimental results demonstrated that optimized parameters significantly improved the dynamic response. As a result, we propose a mechanism for hybrid vehicle performance and report the characteristics of an electronic throttle. The improvement in throttle opening can be verified by adjusting the P term. Full article
(This article belongs to the Topic Vehicle Dynamics and Control, 2nd Edition)
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20 pages, 6592 KiB  
Article
Multiscale Modeling of Plasma-Assisted Non-Premixed Microcombustion
by Giacomo Cinieri, Ghazanfar Mehdi and Maria Grazia De Giorgi
Aerospace 2024, 11(9), 697; https://doi.org/10.3390/aerospace11090697 - 26 Aug 2024
Viewed by 3810
Abstract
This work explores microcombustion technologies enhanced by plasma-assisted combustion, focusing on a novel simulation model for a Y-shaped device with a non-premixed hydrogen-air mixture. The simulation integrates the ZDPlasKin toolbox to determine plasma-produced species concentrations to Particle-In-Cell with Monte Carlo Collision analysis for [...] Read more.
This work explores microcombustion technologies enhanced by plasma-assisted combustion, focusing on a novel simulation model for a Y-shaped device with a non-premixed hydrogen-air mixture. The simulation integrates the ZDPlasKin toolbox to determine plasma-produced species concentrations to Particle-In-Cell with Monte Carlo Collision analysis for momentum and power density effects. The study details an FE-DBD plasma actuator operating under a sinusoidal voltage from 150 to 325 V peak-to-peak and a 162.5 V DC bias. At potentials below 250 V, no hydrogen dissociation occurs. The equivalence ratio fitting curve for radical species is incorporated into the plasma domain, ensuring local composition accuracy. Among the main radical species produced, H reaches a maximum mass fraction of 8% and OH reaches 1%. For an equivalence ratio of 0.5, the maximum temperature reached 2238 K due to kinetic and joule heating contributions. With plasma actuation with radicals in play, the temperature increased to 2832 K, and with complete plasma actuation, it further rose to 2918.45 K. Without plasma actuation, the temperature remained at 300 K, reflecting ambient conditions and no combustion phenomena. At lower equivalence ratios, temperatures in the plasma area consistently remained around 2900 K. With reduced thermal power, the flame region decreased, and at Φ = 0.1, the hot region was confined primarily to the plasma area, indicating a potential blow-off limit. The model aligns with experimental data and introduces relevant functionalities for modeling plasma interactions within microcombustors, providing a foundation for future validation and numerical models in plasma-assisted microcombustion applications. Full article
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24 pages, 2447 KiB  
Article
Feasibility Analysis for Active Noise Cancellation Using the Electrical Power Steering Motor
by Dominik Schubert, Simon Hecker, Stefan Sentpali and Martin Buss
Acoustics 2024, 6(3), 730-753; https://doi.org/10.3390/acoustics6030040 - 31 Jul 2024
Cited by 1 | Viewed by 2184
Abstract
This paper describes the use of an electric drive as an acoustic actuator for active noise cancellation (ANC). In the presented application, the idea is to improve the noise, vibration, harshness (NVH) characteristics of passenger cars without using additional active or passive damper [...] Read more.
This paper describes the use of an electric drive as an acoustic actuator for active noise cancellation (ANC). In the presented application, the idea is to improve the noise, vibration, harshness (NVH) characteristics of passenger cars without using additional active or passive damper systems. Many of the already existing electric drives in cars are equipped with the required hardware components to generate noise and vibration, which can be used as compensation signals in an ANC application. To demonstrate the applicability of the idea, the electrical power steering (EPS) motor is stimulated with a control signal, generated by an adaptive feedforward controller, to reduce harmonic disturbances at the driver’s ears. As it turns out, the EPS system generates higher harmonics of the harmonic compensation signal due to nonlinearities in the acoustic transfer path using a harmonic excitation signal. The higher harmonics impair an improvement in the subjective hearing experience, although the airborne noise level of the harmonic disturbance signal can be clearly reduced at the driver’s ears. Therefore, two methods are presented to reduce the amplitude of the higher harmonics. The first method is to limit the filter weights of the algorithm to reduce the amplitude of the harmonic compensation signal. The filter amplitude limitation also leads to a lower amplitude of the higher harmonics, generated by the permanent magnet synchronous machine (PMSM). The second method uses a parallel structure of adaptive filters to actively reduce the amplitude of the higher harmonics. Finally, the effectiveness of the proposed ANC system is demonstrated in two real driving situations, where in one case a synthetic noise/vibration induced by a shaker on the front axle carrier is considered to be the disturbance, and in the other case, the disturbance is a harmonic vibration generated by the combustion engine. In both cases, the subjective hearing experience of the driver could be clearly improved using the EPS motor as ANC actuator. Full article
(This article belongs to the Special Issue Active Control of Sound and Vibration)
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16 pages, 15983 KiB  
Article
A Numerical Investigation of Supersonic Combustion Flow Control by Nanosecond-Pulsed Actuations
by Yilun Yan, Jiangfeng Wang, Jianying Lan and Keyu Li
Energies 2024, 17(1), 201; https://doi.org/10.3390/en17010201 - 29 Dec 2023
Cited by 2 | Viewed by 1076
Abstract
The efficiency of supersonic combustion is largely dependent on inlet and injection parameters. Additional energy input is required in some off-design conditions, and nanosecond discharge actuation can be a solution. In the present study, a phenomenological model of a nanosecond-pulsed surface dielectric barrier [...] Read more.
The efficiency of supersonic combustion is largely dependent on inlet and injection parameters. Additional energy input is required in some off-design conditions, and nanosecond discharge actuation can be a solution. In the present study, a phenomenological model of a nanosecond-pulsed surface dielectric barrier discharge (NS-SDBD) actuator was developed to analyze the combustion enhancement effect for a supersonic combustor with transverse H2 injection. A seven-reaction H2–air combustion model was adopted for the numerical simulation. Dynamic mode decomposition (DMD) was employed to acquire temperature perturbation in spatial and temporal domains. The results show that the actuator provides additional temperature-increment and species transportation through compression waves. The combustion enhancement effect is mainly attributed to the flow perturbation in the shear layer, which promotes the turbulent diffusion of fuel. Given the same power input, the combustion efficiency at the shockwave reflection point is increased by 17.5%, and the flame height is increased by 15.4% at its maximum. Full article
(This article belongs to the Special Issue Internal Combustion Engine Performance 2023)
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14 pages, 3202 KiB  
Article
Numerical Study on Combustion-Driven Jet Actuation for Aerodynamic Control of Airfoil Flows
by Taesoon Kim, Suhyeon Park and Ilyoup Sohn
Energies 2023, 16(24), 8008; https://doi.org/10.3390/en16248008 - 11 Dec 2023
Viewed by 1283
Abstract
In this study, a numerical investigation is conducted on combustion-driven pulsed-jet actuation to control the flow around a lifting surface. Based on relevant experimental measurements and computations, high-speed jets are generated from the impulsive variation in pressure at the actuator boundary. A supersonic [...] Read more.
In this study, a numerical investigation is conducted on combustion-driven pulsed-jet actuation to control the flow around a lifting surface. Based on relevant experimental measurements and computations, high-speed jets are generated from the impulsive variation in pressure at the actuator boundary. A supersonic jet flow is momentarily generated by combustion in a reaction chamber of the actuator, and the flow interacts with the external flow around the lifting surface and alters the aerodynamic characteristics. The computational results indicate that the flow control performance of the jet actuation is significant at a high-incidence angle of attack, such as beyond the stall angle, whereas the impact is minimal at low angles of attack, such as in the linear lift region. Repetitive jet actuation can produce additional momentum to the external flow and alters the pressure distribution on the suction surface, particularly downstream of the actuator location. This pressure variation from the actuation yields an additional lift force on the lifting surface and reduces the amplitude of the aerodynamic moment at a given angle of attack, thus enhancing the aerodynamic performance of the airfoil. Full article
(This article belongs to the Special Issue Combustion and Flame: Latest Research)
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22 pages, 8932 KiB  
Article
Hybrid Solenoids Based on Magnetic Shape Memory Alloys
by Manuel Mauch, Marco Hutter and Bernd Gundelsweiler
Actuators 2023, 12(8), 328; https://doi.org/10.3390/act12080328 - 15 Aug 2023
Cited by 1 | Viewed by 2224
Abstract
The mobility of today and tomorrow is characterized by technological change and new challenges in drive concepts such as electric or hydrogen vehicles. Abolishing conventional combustion engines creates even more need for switching or valve technology in mobility systems. For switching and controlling [...] Read more.
The mobility of today and tomorrow is characterized by technological change and new challenges in drive concepts such as electric or hydrogen vehicles. Abolishing conventional combustion engines creates even more need for switching or valve technology in mobility systems. For switching and controlling purposes, solenoids are used in large numbers and in a wide variety of applications, thus making a significant contribution to the overall success of the energy transition, and not only in the automotive sector. Despite their long existence, continued research is being carried out on solenoids involving new materials and actuator concepts. Great interest is focused on providing an adjustable force–displacement characteristic while simultaneously reducing the noise during switching. At IKFF, research is being conducted on hybrid electromagnets in the border area of switching and holding solenoids. This paper aims to present the major advantages of this hybrid drive concept based on an electromagnetic FEA simulation study of two drive concepts and specially developed and characterized prototypes with magnetic shape memory (MSM) alloys. The concepts differ in the spatial orientation of the MSM sticks to generate an active stroke of the plunger, which contributes to a beneficial force–displacement characteristic and lower power consumption while minimizing switching noise. Full article
(This article belongs to the Special Issue Innovative Actuators Based on Shape Memory Alloys)
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45 pages, 3956 KiB  
Review
Prospects of Controlled Auto-Ignition Based Thermal Propulsion Units for Modern Gasoline Vehicles
by Abdullah U. Bajwa, Felix C. P. Leach and Martin H. Davy
Energies 2023, 16(9), 3887; https://doi.org/10.3390/en16093887 - 4 May 2023
Cited by 4 | Viewed by 3272
Abstract
Gasoline engines employing the spatially distributed auto-ignition combustion mode, known as controlled auto-ignition (CAI), are a prospective technology for significantly improving engine efficiency and reducing emissions. This review paper provides an overview of developments in various gasoline CAI technologies and discusses their attendant [...] Read more.
Gasoline engines employing the spatially distributed auto-ignition combustion mode, known as controlled auto-ignition (CAI), are a prospective technology for significantly improving engine efficiency and reducing emissions. This review paper provides an overview of developments in various gasoline CAI technologies and discusses their attendant strengths and weaknesses. Hybrid propulsion systems powered by high-efficiency gasoline CAI engines can provide a low-carbon pathway for mobility sector decarbonisation. Therefore, this paper focuses on the challenges and opportunities of CAI implementation, especially for electrified powertrains. Different control actuators that can extend the CAI operating range are discussed, and opportunities for synergistic operation between thermal and electric components of hybridised powertrains are identified. Such synergies can remove impediments in the way of CAI system adoption and can, thus, support CAI adoption and maximise efficiency gains from its implementation. The prospects of supporting CAI combustion for different powertrain electrification levels, hybrid architectures, engine size, and energy management systems are discussed. Load levelling offered by electrified powertrains through CAI-favouring energy management strategies has the potential to substantially relax the operating point requirements for CAI-based thermal propulsion units and to remove the need for expensive actuators. The highly flexible spark-assisted partially premixed compression ignition hybrid mode (SACI-PPCI) emerges as a promising CAI strategy for conventional powertrains, and the moderately flexible spark-assisted compression ignition (SACI) configuration can be a cost-effective thermal propulsion mode for electrified powertrains. Full article
(This article belongs to the Section K: State-of-the-Art Energy Related Technologies)
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20 pages, 6479 KiB  
Article
Combustion Characteristics of Hydrogen/Air Mixtures in a Plasma-Assisted Micro Combustor
by Giacomo Cinieri, Donato Fontanarosa and Maria Grazia De Giorgi
Energies 2023, 16(5), 2272; https://doi.org/10.3390/en16052272 - 27 Feb 2023
Cited by 2 | Viewed by 3090
Abstract
This work performs an analysis of plasma-assisted non-premixed H2-air flames in Y-shaped micro combustors in the presence of field emission dielectric barrier discharge (FE-DBD) plasma actuators. The combustion, flow, and heat transfer characteristics are numerically investigated, and the effect of sinusoidal [...] Read more.
This work performs an analysis of plasma-assisted non-premixed H2-air flames in Y-shaped micro combustors in the presence of field emission dielectric barrier discharge (FE-DBD) plasma actuators. The combustion, flow, and heat transfer characteristics are numerically investigated, and the effect of sinusoidal plasma discharges on combustion performance is examined at various equivalence ratios (φ). A coupled plasma and chemical kinetic model is implemented, using a zero-dimensional model based on the solution of the Boltzmann equation and the ZDPlasKin toolbox to compute net charges and radical generation rates. The estimated body forces, radical production rates, and power densities in the plasma regions are then coupled with hydrogen combustion in the microchannel. Plasma-assisted combustion reveals improvements in flame length and maximum gas temperature. The results demonstrate that FE-DBDs can enhance mixing and complete the combustion of unreacted fuel, preventing flame extinction. It is shown that even in cases of radical and thermal quenching, these plasma actuators are essential for stabilizing the flame. Full article
(This article belongs to the Special Issue Innovation Research in Micro Scale Flows and Combustion)
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42 pages, 16791 KiB  
Review
Power Electronics Converters for Electric Vehicle Auxiliaries: State of the Art and Future Trends
by Ramy Kotb, Sajib Chakraborty, Dai-Duong Tran, Ekaterina Abramushkina, Mohamed El Baghdadi and Omar Hegazy
Energies 2023, 16(4), 1753; https://doi.org/10.3390/en16041753 - 9 Feb 2023
Cited by 32 | Viewed by 8166
Abstract
Electric vehicles (EVs) are expected to take over the transportation and mobility market over traditional internal combustion engine (ICE) vehicles soon. The internal power demands of EVs are expected to increase. The reason for this is to achieve a longer driving range for [...] Read more.
Electric vehicles (EVs) are expected to take over the transportation and mobility market over traditional internal combustion engine (ICE) vehicles soon. The internal power demands of EVs are expected to increase. The reason for this is to achieve a longer driving range for the EV and to provide the required power for the low-voltage (LV) network auxiliary loads. To illustrate, there are extra added sensors, cameras, and small actuating motors, especially for future autonomous vehicles. Therefore, a new electrical/electronic (E/E) architecture is required to convert the high-voltage (HV) traction battery voltage (e.g., 320–800 V DC) to the standard LV levels with high current ratings of 5 kW and more. This HV-LV DC-DC converter is known in the literature as an auxiliary power module (APM). The standard LV rails in an EV are the 12 V/24 V rail to supply for an instant the EV’s lighting and electronic control units (ECUs), while the 48 V rail is required for propulsive loads, such as air compressors and electric power steering systems. Furthermore, in a few applications, this converter is responsible for voltage upwards to support the start of a hybrid vehicle or emergency backup power handling, which requires bidirectional capability. Therefore, in this paper, possible APM topologies for EV applications are presented. In line with this, the main standards and safety requirements of the APMs are presented. Detailed quantitative and qualitative comparisons between topologies and their associated control schemes are discussed. In addition, the placement of the APM in the EV cooling cycle has been investigated and demonstrated. Finally, the industrial trends and future research targets for the APM in automotive applications are outlined. Full article
(This article belongs to the Section E: Electric Vehicles)
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10 pages, 2719 KiB  
Article
Modeling and Control of a Multiple-Heat-Exchanger Thermal Management System for Conventional and Hybrid Electric Vehicles
by Zaker A. Syed and John R. Wagner
Designs 2023, 7(1), 19; https://doi.org/10.3390/designs7010019 - 1 Feb 2023
Cited by 3 | Viewed by 2985
Abstract
The powertrain in combustion engine and electric vehicles requires a thermal management system to regulate the operating temperature of the under-hood components. The introduction of computer-controlled cooling system actuators (e.g., variable speed fans, pump, and valves) enables power savings over drive cycles. The [...] Read more.
The powertrain in combustion engine and electric vehicles requires a thermal management system to regulate the operating temperature of the under-hood components. The introduction of computer-controlled cooling system actuators (e.g., variable speed fans, pump, and valves) enables power savings over drive cycles. The radiator is typically sized for maximum heat rejection per environmental and vehicle thermal loading conditions. This paper explores the use of multiple radiators to adapt the cooling system operations to driving demands. A nonlinear multiple-input (i.e., fan array speed, pump, and outlet valve positions) thermal model is presented to predict system behavior. A stateflow controller has been designed and implemented to maintain the component temperature within a desired range (~80 °C). A series of experimental tests have been conducted to compare the proposed architecture’s performance against a single radiator design. A standard driving cycle featuring low (20 kW) and high (40 kW) heat loads was implemented in the laboratory for a vehicle starting from rest. The coolant temperature tracking, fan speeds, and fan power draw were studied over the representative operating cycle. The test results show a much faster warmup time (~10 min) and temperature tracking for the twin radiator experimental test as compared to the single radiator (~13 min). The net fan energy consumption was reduced by 4.6% with the twin radiator as opposed to the single-radiator configuration. Considering that engines usually operate at idle to medium loads, these findings can improve the powertrain’s overall performance. Full article
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16 pages, 4048 KiB  
Article
Experimental Evaluation of the Influence of the Diameter of the Outlet Nozzle Bore of a Gas Injector on Its Flow Characteristic
by Dariusz Szpica, Bogusław Toczko, Andrzej Borawski and Grzegorz Mieczkowski
Appl. Sci. 2023, 13(3), 1700; https://doi.org/10.3390/app13031700 - 29 Jan 2023
Cited by 2 | Viewed by 2431
Abstract
Despite the growing share of electrically powered vehicles, internal combustion engines are still one of the primary sources of propulsion in transportation. One way to decarbonize engines is to use alternative fuels, where liquefied petroleum gas (LPG) accounts for a large share. Popular [...] Read more.
Despite the growing share of electrically powered vehicles, internal combustion engines are still one of the primary sources of propulsion in transportation. One way to decarbonize engines is to use alternative fuels, where liquefied petroleum gas (LPG) accounts for a large share. Popular car gas systems are LPG indirect vapor phase injection systems, in which the low-pressure gas-phase injector is the actuator. The purpose of the research and analysis presented in this paper is to determine the flow characteristics of three injectors that are structurally different depending on the diameter of the outlet nozzle bore. The tests are conducted, which is new, with pulsed operation of the injector, which, as it turned out, helps explain the discrepancies found. The obtained characteristics are fitted with a polynomial of the second degree, obtaining high-quality indices. In the group of three tested injectors, the average values of volumetric flow rate decreases relative to the maximum by 19.6 and 35.8%. Differences in opening times of 29.3 and 36.6%, respectively, are cited as one of the main reasons for this. Closing times are similar to each other. In addition, the injector with the highest volumetric flow rate and the shortest opening time obtains 1.8 and 9.94% lower average cycle pressures measured at the outlet of the injector nozzle. The differences in opening times and average cycle pressures are considered as possible reasons for the differences in flow characteristics. The obtained characteristics are applicable to engine conversions and calculations. Full article
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13 pages, 4721 KiB  
Article
New Actuation Control for Hybrid Electromagnetic Valve Train
by Yaojung Shiao, Mahendra Babu Kantipudi and Chang-Bo Weng
Appl. Sci. 2022, 12(20), 10449; https://doi.org/10.3390/app122010449 - 17 Oct 2022
Cited by 3 | Viewed by 3397
Abstract
Nowadays, vehicle industries are trying to introduce actively controllable variable valve trains to achieve maximumly efficient internal combustion engines. The electromagnetic valve train (EMV) is one of the promising valve actuators. A traditional electromagnet valve needs to be continuously supplied with current and [...] Read more.
Nowadays, vehicle industries are trying to introduce actively controllable variable valve trains to achieve maximumly efficient internal combustion engines. The electromagnetic valve train (EMV) is one of the promising valve actuators. A traditional electromagnet valve needs to be continuously supplied with current and consumes more energy during valve opening and closing, and the permanent magnet-assisted valves have a demagnetization issue. Thus, this study presents a hybrid permanent magnet electromagnetic valve (PMEMV), which needs a power supply only for a short interval of time during valve opening or closing; eventually, this PMEMV consumes much less energy than conventional EMVs. This paper proposed an improved control approach for this hybrid PMEMV to achieve variable valve actuation. Magnetic stimulation was performed on the proposed valve train to analyze the direction of the magnetic circuit during the valve actuation. An improved magnetic circuit control method was introduced to achieve the release and attraction of the armature. This innovative magnetic circuit control can make the armature effectively attract at each apex, so that the PMEMV can be effectively and completely actuated. The prototype of the valve train and the experimental platform were developed to test and validate the real-time performance of the composite EM valve. Peripheral sensor components were used to measure the valve displacement. The experimental results proved that the concept of the innovative magnetic-circuit drive and control can enable the successful operation of the hybrid compound EM valve. Full article
(This article belongs to the Topic Innovation of Applied System)
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16 pages, 8806 KiB  
Article
The Characteristics of Gliding Arc Plasma and Its Activating Effect for Ramjet Combustion
by Jiulun Sun, Di Jin, Shengfang Huang, Kai Zhang, Weiqi Chen and Xinyao Cheng
Energies 2022, 15(12), 4260; https://doi.org/10.3390/en15124260 - 9 Jun 2022
Cited by 3 | Viewed by 2604
Abstract
In order to improve the combustion performance of a ramjet under low temperature and pressure, a gliding arc plasma actuator was designed based on a typical evaporation flameholder. The discharge characteristics, as well as the activating effect of single-channel and three-channel gliding arc [...] Read more.
In order to improve the combustion performance of a ramjet under low temperature and pressure, a gliding arc plasma actuator was designed based on a typical evaporation flameholder. The discharge characteristics, as well as the activating effect of single-channel and three-channel gliding arc plasma under different carrier gas flow rates, were studied. Results show that with the increase in the carrier gas flow rate, the average duration of the gliding arc discharge becomes shorter, while the average power increases, and the specific input energy decreases. Compared with single-channel discharge, three-channel discharge has higher discharge power and energy injection rate, which makes a bigger actuated space. Through gliding arc plasma, the kerosene is cracked and H2, CH4, C2H2, C2H4, C3H6 and other small molecule components are produced. For three-channel gliding arc discharge, the effective cracking rate and the production rate of each component are higher than those of the single-channel discharge; both of them gradually increase with the increase in the carrier gas flow rate. The experiment results indicate that three-channel gliding arc plasma can effectively widen the ignition boundary and improve the combustion efficiency of ramjet combustion. The ignition pressure boundary is expanded from 60 kPa to 50 kPa under 390 K; the combustion efficiency is increased from 76% to 82%. Full article
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19 pages, 6893 KiB  
Article
Effects of Nanosecond Repetitively Pulsed Discharges Timing for Aeroengines Ignition at Low Temperature Conditions by Needle-Ring Plasma Actuator
by Ghazanfar Mehdi, Sara Bonuso and Maria Grazia De Giorgi
Energies 2021, 14(18), 5814; https://doi.org/10.3390/en14185814 - 14 Sep 2021
Cited by 8 | Viewed by 2687
Abstract
These days, various national and international research organizations are working on the development of low NOx combustors. The present work describes the experimental and numerical characterization of flow dynamics and combustion characteristics in a rectangular burner. A ring-needle type plasma actuator was [...] Read more.
These days, various national and international research organizations are working on the development of low NOx combustors. The present work describes the experimental and numerical characterization of flow dynamics and combustion characteristics in a rectangular burner. A ring-needle type plasma actuator was developed and driven by a high voltage nanosecond pulsed generator under atmospheric conditions. Smoke flow visualizations and Proper Orthogonal Decomposition (POD) were carried out to identify the relevant flow structures. Electrical characterization of the non-reactive flow was carried out to predict the electrical power and the optimum value of the reduced electric field (EN), which is useful for the implementation of a numerical model for the study of plasma-assisted ignition. A detailed plasma kinetic mechanism integrated with all excited species was considered and validated with experimental studies. Numerical modeling of plasma ignition has been performed by coupling ZDPlasKin with CHEMKIN. Energy and power consumption for methane/air plasma actuation is higher than the air plasma actuation. This could be due to the excitation and ionization of methane that required more energy deposition and power. The mole fraction of O atoms and ozone was higher in the air than the methane/air actuation. However, O atoms were produced in a very short time interval of 10−7 to 10−6 s; in contrast, the concentration of ozone was gradually increased with the time interval and the peak was observed around 10−1 s. Plasma discharges on the methane/air mixture also produced radicals that played a key role to enhance the combustion process. It was noticed that the concentration of H species was high among all radicals with a concentration of nearly 10−1. The concentration peak of CH3 and OH was almost the same in the order of 10−2. Finally, the mixture ignition characteristics under different low inlet temperatures were analyzed for both air and methane/air plasma actuation in the presence of different plasma discharges pulses numbers. Results showed that it is possible to reach flame ignition at inlet temperature lower than the minimum required in the absence of plasma actuation, which means ignition is possible in cold flow, which could be essential to address the re-ignition problems of aeroengines at high altitudes. At Ti = 700 K, the ignition was reached only with plasma discharges; ignition time was in the order of 0.01 s for plasma discharges on methane/air, lower than in case of plasma in air, which permitted ignition at 0.018 s. Besides this, in the methane/air case, 12 pulses were required to achieve successful ignition; however, in air, 19 pulses were needed to ignite. Full article
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17 pages, 56273 KiB  
Article
A Pneumatic Generator Based on Gas-Liquid Reversible Transition for Soft Robots
by Guolong Zhang, Guilin Yang, Yimin Deng, Tianjiang Zheng, Zaojun Fang, Hao Zhang and Xiongyu Jiang
Actuators 2021, 10(5), 103; https://doi.org/10.3390/act10050103 - 13 May 2021
Cited by 5 | Viewed by 3518
Abstract
The soft robots actuated by pressure, cables, thermal, electrosorption, combustion and smart materials are usually faced with the problems of poor portability, noise, weak load capacity, small deformation and high driving voltages. In this paper, a novel pneumatic generator for soft robots based [...] Read more.
The soft robots actuated by pressure, cables, thermal, electrosorption, combustion and smart materials are usually faced with the problems of poor portability, noise, weak load capacity, small deformation and high driving voltages. In this paper, a novel pneumatic generator for soft robots based on the gas-liquid reversible transition is proposed, which has the advantages of large output force, easy deformation, strong load capacity and high flexibility. The pressure of the pneumatic generator surges or drops flexibly through the reversible transformation between liquid and gas phase, making the soft actuator stretch or contract regularly, without external motors, compressors and pressure-regulating components. The gas-liquid reversible-transition actuation process is modeled to analyze its working mechanism and characteristics. The pressure during the pressurization stage increases linearly with a rate regulated by the heating power and gas volume. It decreases exponentially with the exponential term as a quadratic function of time at the fast depressurization stage, while with the exponential term as a linear function of time at the slow depressurization stage. The drop rate can be adjusted by changing the gas volume and cooling conditions. Furthermore, effectiveness has been verified through experiments of the prototype. The pressure reaches 25 bar with a rising rate of +3.935 bar/s when 5 mL weak electrolyte solution is heated at 800 W, and the maximum depressurization rate in air cooling is –3.796 bar/s. The soft finger actuated by the pneumatic generator can bend with an angular displacement of 67.5°. The proposed pneumatic generator shows great potential to be used for the structure, driving and sensing integration of artificial muscles. Full article
(This article belongs to the Section Actuators for Robotics)
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