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Turbulent jet ignition (TJI) combustion using pre-chamber ignition can accelerate the combustion speed in the cylinder and has garnered growing interest in recent years. However, it is complicated for the optimization of the pre-chamber structure and combustion system. This study investigated the effects of the pre-chamber structure and the intake ports on the combustion characteristics of a gasoline engine through CFD simulation. Spark ignition (SI) combustion simulation was also conducted for comparison. The results showed that the design of the pre-chamber that causes the jet flame colliding with walls severely worsen the combustion, increasing the knocking intendency, and decrease the thermal efficiency. Compared with SI combustion mode, the TJI combustion mode has the higher heat transfer loss and lower unburned loss. The well-optimized pre-chamber can accelerate the flame propagation with knock suppression.

Toyota has developed a new 2.4L L4 turbo (2.4L-T) engine with 8AT and 1-motor hybrid electric powertrains for midsize pickup trucks. The aim of these powertrains is to fulfill both strict fuel economy and emission regulations toward “Carbon Neutrality”, while exceeding customer expectations. The new 2.4L L4 turbocharged gasoline engine complies with severe Tier3 Bin30/LEVIII SULEV30 emission regulations for body-on-frame midsize pickup trucks improving both thermal efficiency and maximum torque. This engine is matched with a newly developed 8-speed automatic transmission with wide range and close step gear ratios and extended lock-up range to fulfill three trade-off performances: powerful driving, NVH and fuel economy. In addition, a 1-motor hybrid electric version is developed with a motor generator and disconnect clutch between the engine and transmission.

In military applications, diesel engines are required to achieve high power outputs and therefore must operate at high loads. This high load operation leads to high piston component temperatures and heat rejection rates limiting the packaged power density of the powertrain. To help predict and understand these constraints, as well as their effects on performance, a thermodynamic engine model coupled to a finite element heat conduction solver is proposed and validated in this work. The finite element solver is used to calculate crank angle resolved, spatially averaged piston temperatures from in-cylinder heat transfer calculations. The calculated piston temperatures refine the heat transfer predictions as well requiring iteration between the thermodynamic model and finite element solver.

FORMULAS relating the various factors of an adjustable-speed V-belt drive-speed variation, power transmission, and service life-are presented here for the first time. Use of these formulas eliminates previous trial-and-error methods of variable-speed-drive designing. Following the procedures and data given in this paper, the designer can now calculate a drive knowing that a V-belt of satisfactory quality will give satisfactory service within the limits of certain design assumptions.

Electrified vehicles are particularly quiet, especially at low speeds due to the absence of combustion noises. This is why there are laws worldwide for artificial driving sounds to warn pedestrians. These sounds are generated using a so-called Acoustic Vehicle Alerting System (AVAS) which must maintain certain minimum sound pressure levels in specific frequency ranges at low speeds. The creation of the sound currently involves an iterative and sometimes time-consuming process that combines composing the sound on a computer with measuring the levels with a car on an outside noise test track. This continues until both the legal requirements and the subjective demands of vehicle manufacturers are met. To optimize this process and reduce the measurement effort on the outside noise test track, the goal is to replace the measurement with a simulation for a significant portion of the development.

Geometry simplification is a critical step of performing conjugate heat transfer analysis utilizing computational fluid dynamics (CFD). This paper provides a standard methodology to simplify the geometry of electric rotating machines such as electrical generators and electrical motors (both air and liquid cooled). These machines are extremely complex in design and CFD plays an imperative role in their optimization. These machines are extensively deployed throughout aerospace and automotive industries where optimization of weight, volume, and performance is paramount especially given the current global transition to renewable energy sources and vehicle hybridization / electrification.

We propose a novel Split Ring Resonator (SRR) metamaterial capable of achieving a total (or complete) bandgap in the material’s band structure, thereby reflecting airborne and structure-borne noise in a targeted frequency range. Electric Vehicles (EVs) experience tonal excitation arising from switching frequencies associated with motors and inverters, which can significantly affect occupant perception of vehicle quality. Recently proposed metamaterial designs reflect airborne noise and structure-borne transverse waves over a band of frequencies, but do not address structure-borne longitudinal waves in the same band. To achieve isolation of acoustic, transverse, and longitudinal elastic waves associated with tonal frequencies, we propose a metamaterial super cell with transverse and longitudinal resonant frequencies falling in a total bandgap. We calculate the resonant frequencies and corresponding mode shapes using finite element (FE) modal analysis.

To meet the ever-increasing demands of the engineering industry, novel approaches to design optimization are essential, especially in fast-paced production environments. Conventional CAD and simulation tools often struggle to keep up with the complexity and speed required for designing critical components. In this context, leveraging Deep Learning technologies presents a promising solution by integrating knowledge from simulations and designs to drastically accelerate product development. With the drive for Electrification, conventional power electronics and systems are becoming more energy dense and hence requires compact and efficient thermal management solutions. Higher energy density is attributed to high power electrical components fitted in packs with shrinking characteristic dimensions and hence needs more efficient and compact thermal management solutions.

Heavy-duty vehicles equipped with polymer electrolyte membrane fuel cells (PEM-FC) are an environmentally friendly alternative to vehicles powered by internal combustion engines. A major challenge for heavy-duty fuel cell vehicles is the potential cooling deficit under high load conditions at high ambient temperatures. To solve this problem, a spray cooling system can be utilized, in which liquid water is sprayed on the main cooler at the front end of the vehicle. The evaporation of the sprayed liquid water results in an increased cooling power. In this paper, the recovery of liquid water within the cathode loop of a mobile PEM-FC system is presented and discussed. For this purpose, three different topologies of the cathode subsystem of the PEM-FC are investigated for recovering liquid water directly from the fuel cell exhaust gas. To obtain liquid water, vapor in the exhaust gas is cooled below the saturation temperature in an additional heat exchanger.

The rapid evolution of battery electric vehicle (BEV) development has highlighted the need to develop BEVs that meet customer demands for both high-performance and space-efficiency. This paper explores the optimization opportunities available within the landscape of BEV powertrains, focusing on the power-dense potential of single-axis powertrain systems. The need to adhere to power density requirements to accommodate performance aspirations while simultaneously yielding more cabin or storage space to the customer creates a challenging problem for designers. With this pursuit, these competing interests must strike a harmonious balance to create the best experience for the customer. The subject of this study is an investigation into a leading competitor's powertrain that explores the potential optimization opportunities available within its already compact single-axis electric transmission.

In this study, the copper corrosion rates of commercially available lubricants used in electrified and conventional transmissions are measured in both vapor and solution phases simultaneously using an updated version of our previously reported wire resistance test [1]. Unlike the commonly used copper strip tests (versions of the ASTM D130) that generally require high temperatures and long times to differentiate the corrosivity of fluids, the wire resistance test is sufficiently sensitive as to allow real time assessment, thus enabling an efficient and cost-effective way to screen lubricant chemistries over a range of potential operating temperatures. The results of even our small study underscores the importance of understanding both the vapor and solution corrosion across a wide range of temperatures.

A need to develop a cooling method with high cooling performance like jet impingement is increased as high power of an inverter is required. Jet Impingement on the dimpled plate would increase thermal performance than that of flat plate. Many previous researchers have dealt with the multi jet impingement on flat plate and some results of the study on dimpled plate evaluate the effect on heat transfer coefficients on several limited cases, making it difficult to apply them to inverter designs. Therefore, in this paper, heat transfer performance, pressure drop, and robustness at micro-scale of jet impingement on the dimpled plate were investigated in detail and the correlations of each performance were proposed. Finally, the optimal design was presented. The cooling performance was influenced by the jet array and the effect of depth and width of the dimples.

With the shift towards electrification, automakers are constantly looking for ways to increase efficiency of the electric vehicles (EVs). Whether through advanced materials, battery technology, powertrain optimization, software optimization, or reliability improvements, these strategies can help improve EV range, performance, and energy efficiency, making EVs a more attractive option for consumers. This paper focuses on powertrain optimization by utilizing a two-speed transmission instead of a conventional single-speed solution. Multi-speed transmissions offer faster acceleration, increased speed, better gradeability, and reduced energy consumption, which translates to increased vehicle range. Cost and space are critical factors in development and are considered when selecting architecture. The gear ratios are selected by solving an optimization problem to minimize the energy loss and maximize the dynamic performance.

The powertrain system plays a crucial role in electric vehicles, exerting significant impact on both the dynamic and economic performances. A breakthrough has been observed by using the dual-motor powertrain system, which outperformed its single-motor counterparts. This study reports a dual-motor powertrain with magnetorheological technology. The powertrain consists of two motors, two magnetorheological brakes and a planetary gear set. Via regulating the brakes, the power transmission flow can be controlled to realise different torque ratios and velocities. The synergetic control of motors and brakes is capable of achieving smooth gear shifting without interruption. This paper details the design of the powertrain system: the structural configuration of the magnetorheological brakes is highlighted, the magnetic field distribution of the brakes under different currents is simulated by COMSOL Multiphysics, and the torque capacities of the brake are also calculated.

Effective design of the lubrication path greatly influences the durability of any transmission system. However, it is experimentally impossible to estimate the internal distribution of the automotive transmission fluid (ATF) to different parts of the transmission system due to its structural complexities. Hybrid vehicle transmission systems usually consist of different types of bearings (ball bearings, thrust bearings, roller bearings, etc.) in conjunction with gear systems. It is a perennial challenge to computationally simulate such complicated rotating systems. Hence, one-dimensional models have been the state of the art for designing these intricate transmission systems. Though quantifiable, the 1D models still rely heavily on some testing data. Furthermore, HEVs (hybrid electric vehicles) desire a more efficient lubrication system compared to their counterparts (Internal combustion engine vehicles) to extend the range of operation on a single charge.

Continuous improvements and innovations towards sustainability in the aviation industry has brought interest in electrified aviation. Electric aircrafts have short missions in which the temporal variability of thermal loads are high. Lithium-ion (Li-ion) batteries have emerged as prominent power source candidate for electric aircrafts and Urban Air Mobility (UAM). UAMs and Electric aircrafts have large battery packs with battery capacity ranging in hundreds or thousands of kWh. If the battery is exposed to temperatures outside the optimum range, the life and the performance of the battery reduces drastically. Hence, it is crucial to have a Thermal Management System (TMS) which would reduce the heat load on battery in addition to cabin, and machinery thermal loads. Thermal management can be done through active or passive cooling. Adding a passive cooling system like Phase Change Material (PCM) to the TMS reduces the design maximum thermal loads.

Electromechanical actuators (EMAs) play a crucial role in aircraft electrification, offering advantages in terms of aircraft-level weight, rigging and reliability compared to hydraulic actuators. To prevent backdriving, skewed roller braking devices called "no-backs" are employed to provide braking torque. These technology components are continuing to be improved with analysis driven design innovations eg. U.S. Pat. No. 8,393,568. The no-back mechanism has the rollers skewed around their own transverse axis that allow for a combination of rolling and sliding against the stator surfaces. This friction provides the necessary braking torque that prevents the backdriving. By controlling the friction radius and analyzing the Hertzian contact stresses, the brake can be sized for the desired duty cycle. No-backs can be configured to provide braking torque for both tensile and compressive backdriving loads.

Scramjet-based hypersonic airbreathers are needed for next-generation defense and space applications. Two scramjet configurations, namely, rectangular and axisymmetric, are primarily studied in the literature. However, there is no quantitative comparison of the performance metrics between these two scramjet configurations. This study investigates the aero-thermo-structural performance of rectangular and axisymmetric scramjet engines at Mach 7 and 25 km altitude. A numerical framework involving computational fluid dynamics and computational structural dynamics is established. The aero-thermo-structural loads on the scramjet flow path are estimated using RANS/FANS simulation. A finite element-based coupled thermo-structural analysis is performed to understand the thermo-structural response. Before using the numerical models for the study, CFD and CSD modules are validated with literature data.

General Motors has recently developed a front-wheel drive version of its two planetary two-mode transmission (2-MT) for a hybrid-electric vehicle powertrain [1]. This newer transmission includes two planetary gears with two transfer clutches and two braking clutches. With activation of designated pairs of these four clutches, four fixed-gear ratios between the transmission's input shaft and output shaft are obtained. In addition, activation of specific individual clutches gives two modes of operation whereby the IC engine speed is decoupled from the vehicle velocity thus providing an electrical continuously variable transmission (ECVT). This present paper extends the power-split analysis in [2] by deriving a safe-operating region (SOR) in the plane of IC engine speed vs. vehicle velocity for the four fixed-gear and two ECVT modes. This SOR is bounded by the speed limitations of the 2-MT components. Similar results are presented for the Toyota Hybrid System II (THS-II) transmission.