Engine Design Research Articles

Data Movement Accelerator Engines on a Prototype Power10 Processor

This article presents the design and implementation of active messaging engines (AMEs) on an IBM Power10 prototype chip. AMEs are tiny, simple, but fully programmable 64-bit processors, for offloading operations related to data movement. AMEs can offload the execution flow of the message passing interface and other messaging stacks from the host central processing unit, enabling truly asynchronous progress to overlap computation and communication. The AMEs are implemented as onboard OpenCAPI-compliant accelerators, leveraging existing OpenCAPI infrastructure. As realized in a 7-nm technology, each AME takes 0.034 mm2 of silicon area and 4.1 mW of power. AME performance is evaluated across several contiguous and noncontiguous memory copy scenarios. AMEs can perform up to the bandwidth limit of their access path to the main memory (32 GB/s) and incur a per-request overhead of about 600 ns. These results indicate that AMEs will confer advantages to general messaging libraries for processing, sending, and receiving on-node and off-node messages.

Лазерный двигатель на основе абляционно-реактивного эффекта в пленках

The operation principle and design of a solid-fuel laser pulse jet engine are proposed. An experimental confirmation of the proposed operation principle of the laser engine has been obtained.

A theoretical framework for the design of molecular crystal engines.

Photomechanical molecular crystals have garnered attention for their ability to transform light into mechanical work, but difficulties in characterizing the structural changes and mechanical responses experimentally have hindered the development of practical organic crystal engines. This study proposes a new computational framework for predicting the solid-state crystal-to-crystal photochemical transformations entirely from first principles, and it establishes a photomechanical engine cycle that quantifies the anisotropic mechanical performance resulting from the transformation. The approach relies on crystal structure prediction, solid-state topochemical principles, and high-quality electronic structure methods. After validating the framework on the well-studied [4 + 4] cycloadditions in 9-methyl anthracene and 9-tert-butyl anthracene ester, the experimentally-unknown solid-state transformation of 9-carboxylic acid anthracene is predicted for the first time. The results illustrate how the mechanical work is done by relaxation of the crystal lattice to accommodate the photoproduct, rather than by the photochemistry itself. The large ∼107 J m-3 work densities computed for all three systems highlight the promise of photomechanical crystal engines. This study demonstrates the importance of crystal packing in determining molecular crystal engine performance and provides tools and insights to design improved materials in silico.

АНАЛИЗ КИНЕМАТИЧЕСКОЙ СХЕМЫ ПОРШНЕВОГО W-ОБРАЗНОГО ДВИГАТЕЛЯ С ПРИЦЕПНЫМИ ШАТУНАМИ

This article presents the analysis and results of analytical, calculation, and design solutions for the development of piston engines for aircraft (tractors, automobiles, etc.). The authors propose an original design of a W-shaped engine with trailer connecting rods and made a comparative analysis of design features. The main feature of the W-shaped engine design is a significant reduction in length, and, consequently, the length of the crankshaft. As known, the manufacturing of internal combustion engine crankshafts is a long, complex, and expensive procedure requiring a number operations for its mechanical and heat treatment. An important aspect of crankshaft design is the calculation of mechanical tension, torsional vibrations, and the hydraulic performance evaluation of the main and connecting rod bearing, including engine balancing as a whole. At the end of the article the operating schemes of the engine section are presented (the section consists of four pistons, two main and two connecting rods bearing kinematically connected to one crankpin). The design differences from the classical schemes of crank-connecting mechanism (CCM) allow us to design the W-shaped engine in accordance with the technical requirements. For example, maximum power can be achieved by using variant “A”, with an increase in the power and heat stress of the parts of the cylinder-piston group (CPG), when the section is organized according to variants “B” or “C”, the loading of CCM parts is increased, but the loading of CPG parts is reduced. Considering that a W-shaped engine with trailed connecting rods has a same piston stroke in main and side cylinders and the workflow pattern in each cylinder is identical and is moved at the crankshaft rotation angle – which allows the engine to be designed according to variants above – the performance characteristics of such an engine are significantly expanded due to electronic control. The authors consider continuation of the work in the implementation of a full set of calculation studies taking into account the design features of the engine with a W-shaped design of CCM.

Study on performance and mechanisms of a novel integrated model with Power & Thermal Management system and turbofan engine

• A novel integrated model is developed by combining PTMS and engine system. • An off-design heat exchanger submodule without specifying detailed geometry is embedded. • The coupling influences of PTMS and engine are revealed over the entire flight envelope. • The weak cooling performance of PTMS arises in high Mach number and altitude regions. With the improvement of modern aircraft performance, thermal management has become increasingly challenging. The power and thermal management system (PTMS) proposed by Honeywell is an integrated approach to solve this problem. Although the PTMS has inevitable mass and energy interactions with the engine, the existing PTMSs are usually designed based on limited flight states without considering the full engine condition. Therefore, we first propose a novel integrated model combining PTMS and engine based on a semi-precise heat exchanger submodule. Parametric analysis is conducted to find out the impact of the engine and PTMS design variables on the propelling and cooling performance of the integrated system, and energy and exergy analyses are adopted to evaluate the degree of coupled effects between PTMS and engine over the whole flight envelope. Results show that the influence of FAN and HPC pressure ratio on refrigerating performance is more significant than the bypass ratio and inlet temperature of HPT at the design point. The cooling efficiency of PTMS is improved by 4.1% and 1.2%, respectively, as the pressure of HPC and FAN rises by 50%. Besides, the refrigerating performance of PTMS gradually weakens with the increasing flight Mach number, while the cooling efficiency reduces by 50% as the Mach number increases from 0 to 1.8. This trend indicates that the working condition and flight environment of the engine need to be considered in the design process of the PTMS system. As for the control variables of PTMS, the refrigerating efficiency of PTMS decreases by 60% when the pressure ratio of PTMS compressor (PTMS_COMP) changes from -33.3% to 33.3%. Inconsistently, the refrigerating efficiency shows a positive correlation with the heat transfer capacity of the kerosene heat exchanger (PTMS_KEHEX) and primary heat exchanger (PTMS_PRHEX). Meanwhile, the impact of the second heat exchanger (PTMS_SEHEX) on the cooling performance of PTMS can be neglected. Above all, in future PTMS designs, the influences of the pressure ratio of PTMS_COMP, the heat transfer capacity of PTMS_KEHEX and PTMS_PRHEX, as well as the engine control variables need to be considered simultaneously.

Выбор параметров турбокомпрессора при проектировании ТРДД

The choice of the main parameters of a turbofan and turbocompressor at the initial stage of two-spool turbofan engine design is considered. To optimize rotation speeds, the number of stages, and determine the diametrical dimensions, line H is highlighted on Smith charts for compressors, and line L –for turbines. These lines are constructed through the tangent points of constant efficiency isolines and parabolas of the formТН/2ac=const and UL/2ac=const. Expressions are proposed that make it possible to determine the values of the total pressure recovery ratio σ at each point of the Smith diagrams for compressorand turbine stages (at corresponding temperature values). Taking this into account, an original method for determining the efficiency of compressors and turbines is proposed. It is shown how to use Smith diagrams to determine parameters not only for complete stages, but alsofor elementary stages in different sections along the height of the flow path. The proposed method makes it possible to maximize the efficiency of turbines due to the appropriate choice of the number of stages, the distribution of total head rise and the position of the mass-average points “mid” for the stages on the Smith diagrams. It is shown how these methods are used when fine-tuning compressors and turbines based on the results of turbofan engine tests

UGVs for Agri Spray with AI assisted Paddy Crop disease Identification

This research work involves data access and control of Unmanned Ground Vehicles (UGVs) which is designed for health monitoring of paddy crops as an exception from traditional monitoring system. The proposed scheme of autonomous navigation of drones is planned to be carried out as per the six milestones for disease detection and control in paddy crops. Drones serve as Unmanned Robotic Vehicles (URV) capable of performing desired tasks in unstructured, uncertain and potentially hostile environments and are remotely-operated without human intervention. URVs function completely as autonomous entities in diversified environments. Current UGVs adhere to different levels of automaticity. Typically the vehicle follows high level waypoints spaced for few hundred meters of distance to provide monitoring of agricultural fields and early detection of the various diseases that may occur in the paddy fields in a polyhouse. To increase the vehicle's abilities, tracking efficiency, obstacle avoidance, path planning or lead and follow up augmented control with Fuzzy Logic Controller (FLC) is incorporated. The distributed autonomous system for information gathering related to the paddy crops in polyhouse is enabled using different sensors, which is a data-intensive task. To increase the robustness of the system, fuzzy controllers are proposed to control the navigation of the proposed UGV in “All terrain conditions”. They are needed to offer problem specific heuristic control knowledge for the Inference Engine Design which occurs due to imprecision and uncertainty of the sensor readings. It also requires low computation time which favours the polyhouse situations. The navigation of UGV and the FLC action will in turn depend on “All terrain traversability” and “dead zone” monitoring. The proposed UGV model is capable of measuring the parameters associated with the paddy crops inside a polyhouse. The various diseases in paddy crops are False Smut (FS), Sheath Blight (SB), Rice Blast (RB), Leaf Scald (LS), Brown Spot (BS), Bacterial Leaf Blight (BLB) and Bakane (BE) which are detected using Convolutional Neural Network (CNN).

Experimental investigation on the vibrational and fluid dynamics behaviour of a turbocharger compressor in the transition to surge operation

High-speed dynamic centrifugal compressors are widely used both in the modern internal combustion engine design and in advanced pressurized cycles and innovative plant layouts as fuel cell systems. Surge strongly limits the stable operating region of centrifugal compressors in low mass flow rate conditions especially during fast transients. Therefore, it is of great importance to investigate transient system dynamic response of compressor surge evolution and early detection of incipient compressor surge. A specific experimental investigation on compressor surge was carried out at the University of Genoa turbocharger test facility and results are presented and analysed in this paper. The activity consists of steady state and transient measurements used to characterize and identify compressor behaviour in correspondence of surge inception conditions. The frequency and time frequency data analysis have been applied on inflow pressure, anemometric and vibrational signals to identify their contents and so to be able to classify compressor operation as stable or unstable. Synchronous averages performed in the time domain have been identified as a suitable algorithmic tool to detect incipient surge conditions. Anemometric signal analysis allowed to identify intermitting phenomena in deep surge conditions may be related to the rise of a rotation stall condition. The obtained results provide original diagnostic and predictive methods to be integrated in a monitoring system capable of preventing surge and extending compressor operating range, performance and reliability to allow the integration with the other plant components.

Determination of the optimal size of the fuel element of the elliptical cross-section of a nuclear reactor

The work is devoted to the process of heat exchange of a nuclear reactor. Attention was paid to improving the reliability of the fuel rods of the nuclear reactor. At the same time, two cases of the cross section of the rod shell were considered: cylindrical and elliptical. Based on the application of the differentiation method, it was shown that the level of thermal stresses arising during the transition from a circular cross-section to an elliptical one decreases. Which confirms the choice of the section of the reduced elements in the form of an ellipse. The optimal size of the section itself was also obtained. The obtained result is useful because by varying the geometric shape of the cross-section, it is possible to reduce the level of thermal stresses that occur, and, consequently, to increase the reliability and durability of nuclear rocket engine designs.

Combined Impact of EGR Rate and Magnetic Intensity on Performance and Emission of C.I. Engine Operated with Blended Fuel

The combined impact of the MFC and EGR methods on the performance of the C.I. engine is investigated experimentally in this study. The work focused on biodiesel fuel under the effect of different EGR rates 10-30% with the optimal value of fuel polarization. At first, the magnetic intensity optimization was done with other engine design parameters by using diesel fuel alone. The study covered a wide range of engine parameters to select the optimal valves. Using the Taguchi approach and orthogonal array L16 to solve the five factors, such as: CR (15,16,17, and 18), IP (175,200,225, and 250 bar), MFC (4000,6000,8000, and 12000 Gauss), load (25,50,75, and 100%), and TI (19, 21, 23, and 27 degree b TDC). The results showed that the diesel engine's optimum parameters were CR=18, IP=200bar, MFC=8000 Gauss, load 100%, and TI=23° b TDC. The results indicated that the coefficient of determination has an excellent level (i.e.), R2 =97.05% Peak fisher valve F=8.37, with normally distributed and significant coefficients in the model, was utilized to test the model capability. The outcome shows that the 10WCO+10% EGR+8000G has higher cylinder pressure and the BTE increased by 12.5% if compared with DF, and lower brake specific fuel consumption.

Design and Implementation of Digital Twin Data Engine

With the advent of the digital twin era, the construction of digital twin engine based on basic twin data plays a very important role in future application scenarios such as intelligent monitoring, dynamic perception, scientific evaluation, intelligent prediction and intelligent decision-making. This paper mainly analyzes the definition of digital twin, the definition of digital twin model, data characteristics and the application scenario of digital twin, and puts forward a design framework and implementation method of digital twin data engine.

Modeling of a Zero CO2 and Zero Heat Pollution Compressed Air Engine for the Urban Transport Sector

Zero CO2 and Zero heat pollution compressed air engine for the urban transport sector is an engine design that is powered and lubricated solely by compressed air. In other to guarantee these functionalities for the engine design, its modeling was done following the mechanical engineering design method. This article highlights the creation of a mathematical model of the engine. This work covers the design synthesis and the analysis of the kinematics of the engine. For the design synthesis; FAST, GRAFCET and later one realization of conceptual sketches all deductions from the problem definition. With the sketches considered, the kinematics and dynamic formulations where later on realized. The design chosen highlight’s the external forces to come principally from an isothermal expansion process of the compressed air what is termed the expansion chamber of the engine. The analysis was done on the kinematics of the engine with considerations of some assumptions. This article ends with remarkable results as it concerns the engine’s simplicity and guaranteed high efficiency. These conclusions were drawn from the compact nature of the design, the low part count and the reduced displaceable masses which give little of no conflicting movements in the engine design.

Investigating the Origins of Cyclic Variability in Internal Combustion Engines Using Wall-Resolved Large Eddy Simulations

Abstract Modern internal combustion engines (ICE) operate at the ragged edge of stable operation characterized by high cycle-to-cycle variations (CCV). A key scientific challenge for ICE is the understanding, modeling, and control of CCV in engine performance, which can contribute to partial burns, misfire, and knock. The objective of this study is to use high-fidelity numerical simulations to improve the understanding of the causes of CCV. Nek5000, a leading high-order spectral element, open source code, is used to simulate the turbulent flow in the engine combustion chamber. Multicycle, wall-resolved large-eddy simulations (LESs) are performed for the General Motors (GM), Transparent Combustion Chamber (TCC-III) optical engine under motored operating conditions. The mean and root-mean-square (rms) of the in-cylinder flow fields at various piston positions are validated using particle image velocimetry (PIV) measurements during the intake and compression strokes. The large-scale flow structures, including the swirl and tumble flow patterns, are analyzed in detail and the causes for cyclic variabilities in these flow features are explained. The energy distribution across the different scales of the flow are quantified using one-dimensional (1D) energy spectra, and the effect of the tumble breakdown process on the energy distribution is examined. The insights from this study can help us develop improved engine designs with reduced cyclic variabilities in the in-cylinder flow leading to enhanced engine performance.

Experimental and numerical analysis of the Portevin–Le Chatelier effect in a nickel-base superalloy for turbine disks application

High-pressure turbine disks are subjected to extreme mechanical and thermal loadings throughout their lifetime. This is the reason why during the design of turboshaft engines, regulation rules impose on manufacturers to demonstrate the integrity of rotating parts, especially turbine disks, with over-speed experiments. To improve the prediction of rotation speed at burst, it is essential to study the viscoplastic behavior and the fracture of the material. The present work focuses on the approach used to calibrate accurately a viscoplastic behavior model at high temperature (500 °C) of nickel-based superalloy Inconel718. The experimental testing campaign includes standard tensile tests on axisymmetric and flat specimens with and without notches. The behavior is described using the McCormick model for dynamic strain aging. This model accounts for the viscoplastic behavior including the range of negative strain rate sensitivity and the Portevin–Le Chatelier (PLC) effect. In addition to global measurements, digital image correlation at high temperature using a speckle directly engraved on the specimen is used to detect and measure the strain carried by the PLC bands. This information is used in the parameter calibration. The consideration of the machine stiffness is shown to be essential in the analysis for a correct description of serrations and of the critical strain for PLC effects. 3D simulations on full specimen geometries samples are performed to validate the finite element model. Finally, a full 3D representative disk geometry simulation is performed to detect instabilities and their propagation due to geometrical singularities.

ГЕОМЕТРИЧНЕ МОДЕЛЮВАННЯ РОБОЧИХ ПРОФІЛІВ І ОБ’ЄМІВ РОТОРНО-ПЛАНЕТАРНИХ МАШИН

A method for calculating a rotary planetary machine of the Wankel system is presented. A feature of the Wankel machine is that the movement of the rotor in relation to the body is carried out using a planetary mechanism, which is based on an internal gear. The proposed method makes it possible to take into account the connection between the parameters of the geometric shape of two pairs of mutually conjugate curves characteristic of the Wankel machine. The first pair of curves are the working profiles of the casing and the rotor. The second pair is formed by the tooth profiles of the internal gears. Accounting for this connection made it possible to find a description of the function of the change in time of working volumes limited by the profiles of the body and rotor (i.e., to determine the productivity of the machine). As a result of the research, it was found that the performance of the Wankel machine can be found by taking into account three features of this machine. The shaping of the conjugated working profiles of the rotor and stator is carried out using a planetary mechanism, for the calculation of which the functions of complex variables are used. The performance function of the machine is determined by the change in time of the volumes of space limited by the working profiles of the rotor and housing. An approximate description of the functions of changing the working volumes of the machine with time was carried out using specially developed graphic constructions. To match the geometrical parameters of the Wankel with the parameters of the tooth profiles of the gear train of the internal clutch, a method of graphic running has been developed. The results obtained are useful because the scheme of the considered Wankel machine is embedded in the design of the internal combustion engine of the same name, as well as in the design of various hydraulic machines, pumps, compressors, etc. Key words: geometric modeling, rotary planetary mechanism, Wankel machine, functions of a complex variable, internal gearing.  

Experimental Investigations of Diesel Engine Performance Using Blends of Distilled Waste Cooking Oil Biodiesel with Diesel and Economic Feasibility of the Distilled Biodiesel

This paper elaborates on the production of distilled biodiesel of standard EN14214 from waste cooking oil (WCO). Its economic viability is assessed and experimental investigations of a single-cylinder, four-stroke engine using a mixture of distilled biodiesel and diesel of Euro 5 standard are described. The physical and chemical characteristics of biodiesel produced from waste cooking oil were determined. Fuel samples prepared with different percentages of biodiesel and diesel were used to run the engine. We observed the effects of increasing the percentage of biodiesel in the mixture on brake power, brake specific fuel consumption, brake thermal efficiency, and the exhaust emission from the engine. The emission species included O2, CO, CO2, NOx, and SO2. Improved engine performance and reduced emissions from the engine were noticed with blended fuels with 10% and 20% distilled WCO biodiesel mixed with 90% and 80% mineral diesel by volume, respectively. The results of this study indicate that the distilled biodiesel blends with mineral diesel can be used as an alternative fuel to run diesel engines without changing the engine design, thereby providing an alternative energy resource with reduced costs for power generation by using engine fuel. An economic assessment and sensitivity analysis were used to determine the feasibility of distilled WCO biodiesel as an alternative fuel to diesel.

Machine Learning-Enabled Prediction of Transient Injection Map in Automotive Injectors With Uncertainty Quantification

AbstractAccurate prediction of injection profiles is a critical aspect of linking injector operation with engine performance and emissions. However, highly resolved injector simulations can take one to two weeks of wall-clock time, which is incompatible with engine design cycles with desired turnaround times of less than a day. Hence, it is important to reduce the time-to-solution of the internal flow simulations by several orders of magnitude to make it compatible with engine simulations. This work demonstrates a data-driven approach for tackling the computational overhead of injector simulations, whereby the transient injection profiles are emulated for a side-oriented, single-hole diesel injector using a Bayesian machine-learning framework. First, an interpretable Bayesian learning strategy was employed to understand the effect of design parameters on the total void fraction field. Then, autoencoders are utilized for efficient dimensionality reduction of the flowfields. Gaussian process models are finally used to predict the spatiotemporal void fraction field at the injector exit for unknown operating conditions. The Gaussian process models produce principled uncertainty estimates associated with the emulated flowfields, which provide the engine designer with valuable information of where the data-driven predictions can be trusted in the design space. The Bayesian flowfield predictions are compared with the corresponding predictions from a deep neural network, which has been transfer-learned from static needle simulations from a previous work by the authors. The emulation framework can predict the void fraction field at the exit of the orifice within a few seconds, thus achieving a speed-up factor of up to 38 × 106 over the traditional simulation-based approach of generating transient injection maps.

Emission-Driven Hybrid Rocket Engine Optimization for Small Launchers

Hybrid rocket engines are a green alternative to solid rocket motors and may represent a low-cost alternative to kerosene fueled rockets, while granting performance and control features similar to that of typical storable liquid rocket engines. In this work, the design of a three-stage hybrid launcher is optimized by means of a coupled procedure: an evolutionary algorithm optimizes the engine design, whereas an indirect optimization method optimizes the corresponding ascent trajectory. The trajectory integration also provides the vertical emission profiles required for the evaluation of the environmental impact of the launch. The propellants are a paraffin-based wax and liquid oxygen. The vehicle is launched from the ground and uses an electric turbo pump feed system. The initial mass is given (5000 kg) and the insertion of the payload into a 600-km circular, and polar orbit is considered as a reference mission. Clusters of similar hybrid rocket engines, with only few differences, are employed in all stages to reduce the development and operational costs of the launcher. Optimization is carried out with the aim of maximizing the payload mass and then minimizing the overall environmental impact of the launch. The results show that satisfactory performance is achievable also considering rocket polluting emissions: the carbon footprint of the launch can be reduced by one fourth at the cost of a 5-kg payload mass reduction.

Prediction of the flame kernel growth rate in spark ignition engine fueled with natural gas, hydrogen and mixtures

The knowledge of combustion duration is a key tool in the development of engines, specially nowadays for engines adapted to new fuels with low C/H ratio such as natural gas and hydrogen. This work is aimed to develop a correlation that predicts the duration of the first phase of combustion until the process becomes turbulent in a SI engine. The flame kernel radius when this transition occurs, Rtr, is the study variable.To determine this variable from the experimental pressure records, a flame kernel growth predictive model is used. The predictive model is adjusted to the experimental data, determining the most appropriate Rtr value.The pressure records of 500 consecutive cycles of 48 test points have been processed. The averaged values of Rtr of each test point have been correlated with the characteristic parameters of the process: turbulence and properties of the fuel–air mixtures. Finally, Rtr and integral length scale ratio is correlated with Damköhler number.A wide range of operating conditions have been studied, reaching the novel conclusion that it is possible to analyze the kernel growth phenomenon from a spatial point of view rather than from a temporal point of view, as had been studied in many previous works.The developed correlation can be used in combustion predictive modeling to support SI engine design. Other practical conclusion from the work, that can be used in SI engine development, is that decreasing the integral length scale reduces the time of the first phase of combustion.

Three-way catalyst modeling and fuel switch optimization of a natural gas bi-fuel-powered vehicle

In contemporary societies, improving engine efficiency and emission are critical targets for engine designers due to the increasing overwhelming popularity of electric powertrains. Compressed natural gas (CNG) is one of the alternatives for traditional fuels. Due to considerable HC emission during vehicle’s cold-start, the vehicle is started with gasoline and is switched to CNG fuel after a while. The optimum fuel switching time and its effect on total tailpipe emissions have not been addressed in the literature. Therefore, this study focuses on the detailed kinetic modeling of a three-way catalytic converter of a bi-fuel (gasoline/CNG) powered vehicle. The simulated results are validated with experimental data of the new European driving cycle (NEDC) emissions test. The pre-exponential factor (A), the energy of activation (E), and the exponent of temperature (β) for the 22 reactions of the three-way catalytic converter are calibrated by optimization. A genetic algorithm is implemented to optimize the reaction coefficients in both CNG and gasoline fuel mode. The validated model is also used to optimize the vehicle's tailpipe emissions in CNG operation conditions. The results reveal that NOx catalyst conversion efficiency is acceptable in highway driving conditions for CNG mode, while the CO conversion efficiency is inappropriate under the same conditions. It is found that THC catalyst efficiency in gasoline is better than CNG mode after cold-start due to the low reactivity of methane. Most gasoline tailpipe emissions are emitted during the cold-start, while CNG tailpipe emissions gradually increase after the cold-start. The fuel switch time from gasoline to CNG is optimized to 48 s after the vehicle start. While the NOx emission decreases by 15% at the end of the driving cycle, THC is not changed after optimization. The only THC reduction optimization goal leads to a switch time increase to 149 s after the start of driving.