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Technical Paper

Effect of Fatigue Loads on Behavior of 2024-T351 Aluminum Conduits for Aircraft Hydraulic Applications

2024-06-01
2024-26-0431
Abstract: Hydraulic systems in aircrafts largely comprise of metallic components with high strength to weight ratios which comprise of 2024 Aluminum and Titanium Ti-6AL-4V. The selection of material is based on low and high pressure applications respectively. For aircraft fluid conveyance products, hydraulic conduits are fabricated by axisymmetric turning to support flow conditions. The hydraulic conduits further carries groves within for placement of elastomeric sealing components. This article presents a systematic study carried out on common loads experienced by fluid carrying conduits and the failure modes induced. The critical failure locations on fluid carrying conduits of 2024-T351 Aluminum was identified, and the Scanning Electron Microscope (SEM) analysis was carried out to identify the characteristic footprints of failure surfaces and crack initiation. Through this analysis, a load to failure mode correlation is established.
Technical Paper

Study of Different Designs of Chevrons for Effective Noise Reduction in Jet Engines

2024-06-01
2024-26-0408
Due to their remarkable efficiency and efficacy, chevrons have emerged as a prominent subject of investigation within the Aviation Industry, primarily aimed at mitigating aircraft noise levels and achieving a quieter airborne experience. Extensive research has identified the engine as the primary source of noise in aircraft, prompting the implementation of chevrons within the engine nozzle. These chevrons function by inducing streamwise vortices into the shear layer, thereby augmenting the mixing process and resulting in a noteworthy reduction of low-frequency noise emissions. Our paper aims to conduct a comparative computational analysis encompassing seven distinct chevron designs and a design without chevrons. The size and configuration of the chevrons with the jet engine nacelle were designed to match the nozzle diameter of 100.48mm and 56.76mm, utilizing the advanced SolidWorks CAD modeling software.
Technical Paper

Sustainable Microalgae-Membrane Photobioreactor (MPBR) System for Onboard Oxygen Production in an Aircraft

2024-06-01
2024-26-0402
The purpose of the Air Generation System is to provide a constant supply of conditioned fresh air to meet the necessary oxygen availability and to prevent carbon dioxide (CO2) concentrations for the occupants in an aircraft. The engine bleed energy or electrical load energy consumed towards this circumstance accounts to be approx. 5% of total fuel burn and in turn, contributes to the global emissions of greenhouse gases. This paper studies the improvement areas of the present conventional system such as fuel burn consumption associated with an aircraft environmental control system (ECS) depending on, the amount of bleed and ram air usage, electric power consumption. Improved systems for propulsion, power generation, sustainability, hybridization, and environmental control can be desirable for an aircraft.
Technical Paper

Thermal Analysis of Prismatic Core Sandwich Structural Panel for Hypersonic Application

2024-06-01
2024-26-0422
Hypersonic flight vehicles have potential applications in strategic defence, space missions, and future civilian high-speed transportation systems. However, structural integration has significant challenges due to extreme aero-thermo-mechanical coupled effects. Scramjet-powered air-breathing hypersonic vehicles experience extreme heat loads induced by combustion, shock waves and viscous heat dissipation. An active cooling thermal protection system for scramjet applications has the highest potential for thermal load management, especially for long-duration flights, considering the weight penalty associated with the heavier passive thermal insulation structures. We consider the case of active cooling of scramjet engine structural walls with endothermic hydrocarbon fuel. We have developed a semi-analytical one-dimensional heat transfer model considering a prismatic core single cooling channel segment as a representative volume element (RVE) to analyse larger scale problems.
Technical Paper

On the Aero-Thermo-Structural Performance of Rectangular and Axisymmetric Scramjet Configurations

2024-06-01
2024-26-0441
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. But, 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 (CFD) and computation structural dynamics (CSD) is established. The aero-thermo-structural loads on the scramjet flow path are estimated using Reynolds-averaged Navier-Stokes 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.
Technical Paper

Knockdown Factor Estimation of Stiffened Cylinders under Combined Loads - A Numerical Study

2024-06-01
2024-26-0417
Airframe section of rockets, missiles and launch vehicles are typically cylindrical in shape. The cylindrical shell is subjected to high axial load and an external pressure during its operation. The design of cylinders subjected to such loads is generally found to be critical in buckling. To minimize the weight of cylinders, it is typically stiffened with rings and stringers on the inner diameter to increase the buckling load factor. Conventionally the buckling load estimated by analytical or numerical means is multiplied by an empirical factor generally called Knockdown factor (kdf) to get the critical buckling load. This factor is considered to account for the variation between theory and experiment and is specified by handbooks or codes. In aerospace industry, NASA SP 8007 is commonly followed and it specifies the kdf as a lower bound fit curve for experimental data .
Technical Paper

Structural Loads for Crew Escape System (CES) of Gaganyaan Launch Vehicle During Abort

2024-06-01
2024-26-0453
Abstract : In any human space flight program, safety of the crew is of utmost priority. In case of exigency during atmospheric flight, the crew is safely and quickly rescued from the launch vehicle using Crew escape system. Crew escape system is a crucial part of the Human Space flight vehicle which carries the crew module away from the ascending launch vehicle by firing its rocket motors (Pitch Motor (PM), Low altitude Escape Motor (LEM) and High altitude Escape Motor (HEM)). The structural loads experienced by the crew escape system during the mission abort are severe as the propulsive forces, aerodynamic forces and inertial forces on the vehicle are significantly high. Since the mission abort can occur at anytime during the ascent phase of the launch vehicle, trajectory profiles are generated for abort at every one second interval of ascent flight time considering several combinations of dispersions on various propulsive parameters of abort motors and aero parameters.
Technical Paper

Comparative Analysis of Axial Flux and Radial Flux Motors for UAV Propulsion: Design and Suitability Assessment

2024-06-01
2024-26-0467
In the architecture of an Unmanned Aerial Vehicle (UAV), a crucial component responsible for the propulsion system is the electric motor. Over the years, different types of electric motors, including Brushless Direct Current (BLDC), have supported the UAV’s propulsion system in diverse configurations. However, in the context of flux flow, the Radial Flux Permanent Magnet Motor (RFPMM) has been given more priority than the Axial Flux Permanent Magnet Motor (AFPMM) due to its sustainability in design and construction. Nevertheless, the AFPMM boasts higher speed, power density, lower weight, and greater efficiency than the RFPMM, because of its shorter flux path and the absence of end-turn winding. Therefore, this paper focuses on conducting a suitability analysis of an AFPMM as a shaft-connected propeller-mounted motor, with the intention of replacing the RFPMM in UAV applications.
Technical Paper

Configuration and Design of Mobile Checkout System for Ground Testing of Winged Body Reusable Launch Vehicle

2024-06-01
2024-26-0454
Abstract Unlike conventional launch vehicles the winged body reusable launch vehicle needs to be tested and evaluated for its functionality during the pre-flight preparation at the runway. The ground based checkout systems for the avionics and actuators performance testing during pre-flight evaluation and actuation are not designed for rapid movement. The new kind of launch vehicle with conventional rocket motor first-stage and winged body upper-stage demands the system testing at Launchpad and at runway. In the developmental flights of the winged body part of the vehicle, the pre-flight testing needs to be carried out extensively at runway. The safety protocol forbids the permanent structure for hosting the checkout system near runway. The alternative is the development of a rapidly deployable and removable checkout system. A design methodology adopting conventional industrial instrumentation systems and maintaining mobility is presented.
Technical Paper

Numerical Approach for the Characterization of the Venting Process of Cylindrical Cells Under Thermal Runaway Conditions

2024-05-06
2024-01-2900
The increasing awareness on the harmful effects on the environment of traditional Internal Combustion Engines (ICE) is driving the industry toward cleaner powertrain technologies such as battery-driven Electric Vehicles. Nonetheless, the high energy density of Li-Ion batteries can cause strong exothermic reactions under certain conditions that can lead to catastrophic results, called Thermal Runaway (TR). Hence, a strong effort is being placed on understanding this phenomena and increase battery safety. Specifically, the vented gases and their ignition can cause the propagation of this phenomenon to adjancent batteries in a pack. In this work, Computational Fluid Dynamics (CFD) are employed to predict this venting process in a LG18650 cylindrical battery. The ejection of the generated gases was considered to analyze its dispersion in the surrounding volume through a Reynolds-Averaged Navier-Stokes (RANS) approach.
Technical Paper

Algorithm to Calibrate Catalytic Converter Simulation Light-Off Curve

2024-04-09
2024-01-2630
Spark ignition engines utilize catalytic converters to reform harmful exhaust gas emissions such as carbon monoxide, unburned hydrocarbons, and oxides of nitrogen into less harmful products. Aftertreatment devices require the use of expensive catalytic metals such as platinum, palladium, and rhodium. Meanwhile, tightening automotive emissions regulations globally necessitate the development of high-performance exhaust gas catalysts. So, automotive manufactures must balance maximizing catalyst performance while minimizing production costs. There are thousands of different recipes for catalytic converters, with each having a different effect on the various catalytic chemical reactions which impact the resultant tailpipe gas composition. In the development of catalytic converters, simulation models are often used to reduce the need for physical parts and testing, thus saving significant time and money.
Technical Paper

Energy Based Hysteresis for Real-Time State Optimization in Hybrid Torque Controls

2024-04-09
2024-01-2778
Through real-time online optimization, the full potential of the performance and energy efficiency of multi-gear, multi-mode, series–parallel hybrid powertrains can be realized. The framework allows for the powertrain to be in its most efficient configuration amidst the constantly changing hardware constraints and performance objectives. Typically, the different gears and hybrid/electric modes are defined as discrete states, and for a given vehicle speed and driver power demand, a formulation of optimization costs, usually in terms of power, are assigned to each discrete states and the state which has the lowest cost is naturally selected as the desired of optimum state. However, the optimization results would be sensitive to numerical exactitude and would typically lead to a very noisy raw optimum state. The generic approach to stabilization includes adding hysteresis costs to state-transitions and time-debouncing.
Technical Paper

From Idle to 7.5 bar IMEPg – Using Fuel Stratification to Control LTGC with Next-Cycle Capability

2024-04-09
2024-01-2821
Low-temperature gasoline combustion (LTGC) engines can provide high efficiencies with very low NOx and soot emissions, but rapid control of the combustion timing remains a challenge. Partial Fuel Stratification (PFS) was demonstrated to be an effective approach to control combustion in LTGC engines. PFS is produced by a double direct injection strategy with most of the fuel injected early in the cycle and the remainder of the fuel supplied by a second injection at a variable time during the compression stroke to vary the amount of stratification. Adjusting the stratification changes the combustion phasing, and this can be done on cycle-to-cycle basis by adjusting the injection timing. In this paper, the ability of PFS to control the combustion during wide engine load sweeps is assessed for regular gasoline and gasoline doped with 2-ethylhexyl nitrate (EHN). For PFS, the load control range is limited by combustion instability and poor combustion efficiency at low loads.
Technical Paper

A Computational Investigation of Ammonia-Fueled Spark Ignited Combustion in a High Tumble Engine

2024-04-09
2024-01-2815
The use of ammonia (NH3), a low life-cycle carbon fuel, is an increasingly popular pathway towards decarbonization in the marine and other sectors. However, NH3 possesses low reactivity and flame speed, making its use in internal combustion engines challenging. These challenges include low efficiency due to incomplete combustion, combustion instability, and fuel slip. Therefore, robustly igniting the fuel and promoting effective flame propagation is critical for NH3 usage in spark-ignited (SI) combustion engines. In a previous study from the authors, full NH3 substitution was achieved in a high-tumble SI engine.
Technical Paper

Optimum Shifting of Hybrid and Battery Electric Powertrain Systems with Motors Before and After a Transmission

2024-04-09
2024-01-2143
This paper proposes an optimization-based transmission gear shifting strategy for electrified powertrains with a transmission. With the demand for reduced vehicle emissions, electrified propulsion systems have garnered significant attention due to their potential to improve vehicle efficiency and performance. An electrified propulsion system architecture of significance includes multiple electric motors and a transmission where some driveline actuators can transmit torque through changing gear ratios. If there is at least one electric motor arranged before the input of the transmission and at least one after the transmission output, a unique design opportunity arises to shift gears in the most energy efficient manner.
Technical Paper

Light Duty engine performance characteristics with Dimethyl Ether and Propane

2024-04-09
2024-01-2126
Paper documents the performance characteristics of a compression ignition HYUNDAI 2.2L engine operating with Dimethyl Ether (DME) and Propane mixtures. The engine features a high-pressure common rail fuel injection system designed to operate with DME and Propane. The main component of the fuel system is a high-pressure pump that incorporates an electronic inlet metering valve commanded on a crank angled base to control the rail pressure. The pump, which requires no pressure regulator, provides the flow needed to the injectors without flow returning to the inlet. Tests are carried out at injection pressures from 300bar to 1000bar, and the engine ECU is aided with the use of an Engine Controller High speed Oversight unit (ECHO) to provide combustion phasing control and improved cylinder-to-cylinder uniformity, providing improved optimization over the testing effort.
Technical Paper

Open-loop Torque Control Strategy based on Constant-Volume Instantaneous Combustion Model

2024-04-09
2024-01-2840
A model-based torque control strategy which is simple and easily adaptable to various types of engines is developed in this paper. A torque model is derived from physics-based constant-volume combustion model, and applications of the model to engine torque control problem are also discussed. As examples, the torque model is calibrated with experimental data collected from two different engines, and simulation and experimental results from the torque control strategy are presented as well.
Technical Paper

Enhancing ducted fuel injection simulations: assessment of RANS turbulence models using LES data

2024-04-09
2024-01-2689
Diesel engine-based transportation is nowadays looking for cleaner combustion solutions and ducted fuel injection (DFI) is emerging as a cutting-edge technology due to its potential to drastically curtail engine-out soot emissions. Although the DFI capability to abate soot formation throughout the diesel combustion process has been demonstrated both in constant-volume and optical engine conditions, its optimization and understanding is still needed for its exploitation on series production diesel engines. For this purpose, computational fluid dynamics (CFD) coupled with low-cost turbulence models, like RANS, can be a powerful tool, especially in the industrial context. However, it is often challenging to obtain reliable RANS-based CFD simulations, especially due to the high dependence of the various state-of-the-art turbulence models on the case study.
Technical Paper

A novel quasi-dimensional model for transient mixing prediction in two-phase multicomponent sprays under flash-boiling conditions

2024-04-09
2024-01-2086
A novel one-dimensional multiphase and multicomponent spray model - hereafter referred to as the Kattke-Weigand model - has been developed to predict the penetration length of both vapor and liquid gasoline sprays under flash-boiling conditions, such as superheated injections. Its formulation is based on mass and momentum equations for unsteady jets and is therefore capable of capturing dynamic effects. Experiments were conducted in a constant volume chamber using various ambient and fuel temperature conditions and a six-hole GDI injector with a separated jet. Macroscopic spray parameters were extracted from the measurements to verify the model's ability to predict both liquid and vapor penetration length and the corresponding spray angles. Apart from the separated jet of the injector used, the other five jets interact strongly with each other under flash boiling conditions, resulting in spray collapse and thus affecting spray characteristics.
Technical Paper

Analysis of Vibration Characteristics of High-Speed Reducer for Pure Electric Vehicles

2024-04-09
2024-01-2721
To address the issue of vibration and noise in electrical drive systems, an analysis of the vibration characteristics of the high-speed reducer in the system was conducted. Through extensive experimentation on the vibration and noise test platform for the integrated electric drive system, the primary sources and frequency components contributing to the system's vibration and noise were meticulously identified. Furthermore, a profound exploration was undertaken to delve into the impact of high-speed reducer gear meshing order vibrations on the overall vibration and noise levels of the electric drive system. To provide a deeper understanding, a dynamic model that encompasses both rigid and flexible elements of the high-speed reducer was meticulously crafted. This model served as the foundation for a rigorous simulation and analysis of the high-speed reducer's vibration characteristics.
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