Propulsion System Configurations Research Articles

Modeling Shipboard Power Systems for Endurance and Annual Fuel Calculations

_ Endurance fuel calculations are used to determine the required volume of fuel tanks; annual fuel calculations are used to estimate the fuel consumed during a year of ship operations, primarily to estimate the projected cost of fuel as part of the life cycle cost estimate. These calculations depend on the fuel rates (kg/h) for different electrical and propulsion system configurations. The fuel rates in turn depend on factors, such as equipment efficiency, prime mover-specific fuel consumption curves, electrical loads, ambient temperature, propulsion loads, and the manner in which the power and propulsion systems, are operated. This paper details how to perform endurance fuel and annual fuel calculations, provides guidance for modeling system components based on data typically provided in data sheets, and provides guidance on the manner in which the power and propulsion systems are operated. Four examples are provided to illustrate the methods using the Smart Ship System Design modeling and simulation tool along with supporting spreadsheets. Keywords Marine design for ships and offshore structures; endurance; fuel efficiency; electrical efficiency; electrical system; performance prediction

A high‐efficiency magnetic‐geared double‐rotor machine with the coreless stator for hybrid aircraft propulsion

AbstractMagnetic‐geared double‐rotor machines are recognized as a promising power‐splitting component in hybrid electric aircrafts (HEAs). However, the high fuel efficiency speed of the turbine engine in HEAs is about 10,000 rpm, whereas conventional topologies suffer from low efficiency at high speed due to its specific operation principle—the magnetic field modulating principle. A coreless stator magnetic‐geared double‐rotor machine (CS‐MGDRM) is proposed to enhance high‐speed efficiency and thus comply with the operation condition of HEAs. First, the machine structure and hybrid propulsion system configuration are introduced, and power‐flow analysis of three basic operation modes is presented. Second, the operation principle of the machine is illustrated, and investigation of electromagnetic performances is carried out by finite element analysis. Third, an analytical model of the machine is developed, based on which the design optimization towards the maximum torque capacity is investigated. Furthermore, the loss distribution law and transmission efficiency are analysed and compared with conventional scheme, and the power factor characteristic is investigated as well. Finally, the overall performance of the proposed machine is evaluated.

Influence of Electric Wing Tip Propulsion on the Sizing of the Vertical Stabilizer and Rudder in Preliminary Aircraft Design

During preliminary aircraft design, the vertical tail sizing is conventionally conducted by the use of volume coefficients. These represent a statistical approach using existing configurations’ correlating parameters, such as wing span and lever arm, to size the empennage. For a more detailed analysis with regard to control performance, the vertical tail size strongly depends on the critical loss of thrust assessment. This consideration increases in complexity for the design of the aircraft using wing tip propulsion systems. Within this study, a volume coefficient-based vertical tail plane sizing is compared to handbook methods and the possibility to reduce the necessary vertical stabilizer size is assessed with regard to the position of the engine integration and their interconnection. Two configurations, with different engine positions, of a hybrid-electric 19-seater aircraft, derived from the specifications of a Beechcraft 1900D, are compared. For both configurations two wiring options are assessed with regard to their impact on aircraft level for a partial loss of thrust. The preliminary aircraft design tool MICADO is used to size the four aircraft and propulsion system configurations using fin volume coefficients. These results are subsequently amended by handbook methods to resize the vertical stabilizer and update the configurations. The results in terms of, e.g., operating empty mass and mission fuel consumption, are compared to the original configurations without the optimized vertical stabilizer. The findings support the initial idea that the connection of the electric engines on the wing tips to their respective power source has a significant effect on the resulting torque around the yaw axis and the behaviour of the aircraft in case of a power train failure, as well as on the empty mass and trip fuel. For only one out of the four different aircraft designs and wiring configurations investigated it was possible to decrease the fin size, resulting in a 53.7% smaller vertical tail and a reduction in trip fuel of 4.9%, compared to the MICADO design results for the original fin volume coefficient.

System-Level Assessment of a Partially Distributed Hybrid Electric Propulsion System

Abstract Hybrid electric propulsion system-based aircraft designs are paving the path toward a future greener aviation sector and thus, have been the major focus of the aeronautical community. The fuel efficiency improvement associated to such propulsion system configurations are realized at the aircraft level. In order to assess such benefits, a radical shift in the subsystem modeling requirements and of a conceptual-level aircraft design environment are necessary. This work highlights performance model development work pertaining to different hybrid electric propulsion system components and the development of a design platform that facilitates tighter integration of different novel propulsion system disciplines at the aircraft level. Furthermore, a serial/parallel partially distributed hybrid electric propulsion system is chosen as the candidate configuration to assess the potential benefits and associated tradeoffs by conducting multidisciplinary design space exploration studies. It is established that the distributed hybrid electric configurations pose the potential for aircraft structural weight reduction benefits. The study further illustrates the impacts of onboard charging during the low thrust requirement segments, quantitatively. The provision of onboard charging lowers the potential for block fuel savings, and improvement in battery specific energy can make it more promising, which is also dependent on the hybridization power level. It is established that distributed propulsion system configurations particularly benefit from a high aspect ratio wing structure, which manifests in high hybridization power levels. A high voltage level transmission system with more efficient electrical components enhances opportunities for achieving block fuel saving benefits.

Comprehensive Load Relief of Launch Vehicle with the Constraints of Legacy Stages

Facing diversified launch needs, it is uneconomical to redevelop new rockets from scratch. The concept of combining legacy modules into a new launcher has become attractive. However, these mature modules may not adapt to new flight profiles due to differences in factors such as the propulsion system configuration, payloads, and trajectories. Thus, structural load relief measures play a key role in module integration. A comprehensive load relief strategy applied in the Long March 8 (LM-8) rocket is introduced, including the inflight load reduction by engine throttling, wind biasing trajectory, and onboard load relief control techniques. A unified analysis process for the elastic loads caused by gusts and fluctuating pressures was proposed, and an integral optimization problem for simultaneous planning with complicated constraints (such as the maximum dynamic pressure, wind biasing, and throttling level and time) is discussed. A real-time load relief technology based on an extended state observer, which predicts the angular acceleration caused by the wind, is proposed. Its efficiency, adaptability, influence on the stability and control accuracy, and application in the LM-8 maiden flight are studied. The proposed scheme expands the launch probability of LM-8 and provides a systematic solution for the load relief design and control of in-service rockets.

Selection of the optimum configuration and calculation studies of the parameters of a cryogenic propulsion system for an unmanned aerial vehicle

A computational study of the parameters of a propulsion system of an unmanned aerial vehicle operating on a cryogenic working medium has been carried out. Liquid nitrogen was selected as the cryogenic working fluid. Two alternative configurations of a cryogenic propulsion system for an unmanned aerial vehicle are presented. The first one is a scheme of an air-heated cryogenic propulsion system of an unmanned aerial vehicle in which air acts as the heat source at an ambient temperature at an altitude of 2000 m. The second one is a scheme wherein the working fluid is heated due to solar energy, in this case solar energy acts as the source of heat. A computational study of a cryogenic propulsion system operating on the open Rankine cycle was carried out, as well as computational studies of possible cryogenic propulsion system configurations. As a result of the studies a comparative analysis of the data obtained was made and a suitable cryogenic propulsion system configuration for an unmanned aerial vehicle with the required parameters was selected.

A review of electrified propulsion system concepts for advanced aircraft

The active development of electrical technology provided leeway to creating fundamentally new configurations of propulsion systems and novel aerodynamic layouts of aircraft. Currently, this area of science is in the initial stage of development, but thanks to its huge potential, the number of projects with new propulsion system configurations is growing annually at an exponential rate. A classification of new types of propulsion system configurations is presented in order to understand its wide variety. Beneficial and negative impacts of each configuration are presented.

A novel hybrid propulsion system configuration and power distribution strategy for light electric aircraft

Similar to the electrification of the automotive industry, the growing concerns with the shortage of fossil fuels has also called for a paradigm shift in aviation industry. To promote the aviation electrification process, it is necessary to develop an efficient energy storage system and a stable power transmission system to improve the reliability and extend the endurance of electric aircraft. This paper designs a novel propulsion system topology and power distribution algorithm for light manned electric aircraft. Firstly, a novel aircraft hybrid propulsion system topology is designed, in which the battery energy storage system can work synergistically with the fuel cell to provide power to the aircraft electric engine. Then, an adaptive energy management framework is developed to distribute the aircraft power requirement between energy storage devices. Meanwhile, an aircraft power balance state recognizer is designed to enhance the dynamic performance of the aircraft and adjust the working state of the propulsion system. The proposed hybrid propulsion system configuration and power distribution algorithm are verified under a prototype two-seater electric aircraft: Alpha Electro. Numerical analysis results indicate that the developed methods can dynamically meet the power requirement of aircraft under fast-charging and peak power requirement scenarios. With the developed hybrid propulsion system, most of the fuel cell high-power working points are moved to the medium and low area, which indicates that the fuel cell is effectively protected. Furthermore, the quantified hydrogen consumption can be reduced by 7.63% comparing to fuel cell electric aircraft.

Optimal Design of Propulsion System Configuration for Electrically Propelled Unmanned Surface Vehicle

Unmanned surface vehicles (USVs) are vessels that operate without any crew onboard. There is an increased demand for USVs in recent years, particularly for the use of water quality monitoring and ocean data mapping. In China, USVs are widely used as a luring fish boat which acts as the assisting boat of light luring seine vessel. One of the main problems of such boat is that the traditional propulsion system is poorly matched with the high energy consumption that is required during certain specific operation, which results in poor vessel performance. A hybrid electric propulsion system configuration solution is proposed to increase the overall propulsion efficiency of such USVs. The typical operating profile was identified and a comprehensive simulation was conducted to demonstrate the compatibility during vessel operations. An intelligent equipment selection analysis was also carried out to recommend the optimal equipment selection by considering a multiobjective problem. The result shows that the configuration solution proposed can reduce fuel consumption and the optimal intelligent selection method can provide a suitable selection solution for decision makers. This article highlights an energy management strategy focusing on the threshold method based on support vector machine pattern recognition. A multiobjective particle swarm optimization algorithm based on the dynamic inertia weight and chaotic motion was used to optimize the equipment selection by considering fuel consumption and emissions. The proposed propulsion system configuration and equipment selection solution can be implemented for the design of USVs, which has a routine fixed operating pattern.

Hybrid electric distributed propulsion overall aircraft design process and models for general aviation (FAST GA)

In the frame of the European objectives in terms of CO2 emissions, the aeronautics is looking for a technological rupture to achieve them, in particular, the aircraft design domain pursuits this through the research of innovative architectures. One of these innovative configurations currently being explored includes the hybrid electric energy source (thermal/electric) for Distributed Electric Propulsion (DEP) architecture. This Paper details a code developed to size a general aviation aircraft at concept level, by only defining its top level requirements and the main architecture parameters. The code can manage both conventional and hybrid power source as well as concentred or distributed propulsion architectures in order to allow the user to evaluate and compare the feasibility and benefits respectively of these innovative architectures. This code is a branch of the code “FAST-CS25” (Future Aircraft Sizing Tool for conventional CS-25 type) held by ONERA/ISAE-SUPAERO. The presented work aims at the expansion of the FAST code to CS-23 conventional type, hybrid electric energy source, and distributed propulsion system configurations. Through this paper, the models and the main sizing loops for the concept design are described, but putting special emphasis on the distributed propulsion aerodynamics and wing mass estimation. These detailed models where validated with the NASA X-57 DEP aircraft satisfactory. The whole concept design loop of a hybrid energy aircraft was validated with the eGenius hybrid energy aircraft.

A Review of Concepts, Benefits, and Challenges for Future Electrical Propulsion-Based Aircraft

Electrification of the propulsion system has opened the door to a new paradigm of propulsion system configurations and novel aircraft designs, which was never envisioned before. Despite lofty promises, the concept must overcome the design and sizing challenges to make it realizable. A suitable modeling framework is desired in order to explore the design space at the conceptual level. A greater investment in enabling technologies, and infrastructural developments, is expected to facilitate its successful application in the market. In this review paper, several scholarly articles were surveyed to get an insight into the current landscape of research endeavors and the formulated derivations related to electric aircraft developments. The barriers and the needed future technological development paths are discussed. The paper also includes detailed assessments of the implications and other needs pertaining to future technology, regulation, certification, and infrastructure developments, in order to make the next generation electric aircraft operation commercially worthy.

Optimization of tugboat propulsion system configurations: A holistic life cycle assessment case study

The International Maritime Organization has initialized a strategy to reduce 30% and 50% of carbon dioxide emissions from marine activities by 2030 and 2050 respectively. It is extremely challenging to achieve but innovative cleaner technologies are under research and development to help control and reduce maritime carbon emission. One fact is that the usage of tugboats has been increasing in recent years as huge demands of marine offshore activities (construction, installation and maintenance of renewable islands and wind farms); therefore, the performance of tugboats should be well-evaluated which could be a valuable contribution to maritime emission reduction. This paper focuses on investigating a tugboat’s life cycle performance, specifically comparing different configurations of the propulsion system and selecting an optimal system with the lowest emissions release, costs and hazard impacts. A case study was carried out comparing five different engine configurations with the help of commercial and in-house developed life cycle assessment software in order to comprehensively evaluate the ship performance. Three main life phases, three evaluation flows, four emission categories and three criteria, were under consideration in this study. The results indicate LCA method and the in-house software could help to compare and determine optimal configurations and the engine configuration with three medium size engines is the optimal one which generated lowest emissions equivalent to 15.5 million euros, invested 14.2 million euros and occur a risk impact equivalent to 1.01 million euros. This paper not only provides a case study for the tugboat configuration assessment but also recommends LCA methodology as a general evaluation method for emission reduction technologies who have to meet the extreme requirements of emission control in the next few decades.

Mission Analysis and Emissions for Conventional and Hybrid-Electric Commercial Transport Aircraft

A feasibility study of a hybrid-electric commercial transport aircraft was conducted by analyzing the simulated performance and lifecycle carbon dioxide () emissions of a conventional single-aisle aircraft and an aircraft with a modified parallel hybrid-electric propulsion system. A flight performance simulation was developed in a MATLAB/Simulink environment using publicly available aircraft data for the Boeing 737-700 commercial transport aircraft and the CFM56-7B26 turbofan engine. A parallel hybrid drivetrain was integrated into the aircraft performance model. Various missions with different degrees of hybridization and battery specific energy densities were simulated and compared to the conventional turbofan case. emissions associated with fuel burn and electricity generation for charging battery systems were modeled for each hybrid aircraft configuration. The results indicated that reductions in emissions per passenger mile were achievable using a parallel hybrid propulsion system as compared to conventional systems of equivalent range. A candidate propulsion system configuration was defined, which used a 50% electrical-power drivetrain and a battery specific energy density of . This configuration was estimated to produce 49.6% less lifecycle emissions than a modern conventional aircraft, with a maximum range equivalent to that of the average of all global flights, making it a viable option for environmentally responsible aviation.

Priming Event Peak Pressures in Liquid Propulsion Systems

An experimental study was conducted to evaluate pressure transient levels in unrestricted and restricted liquid monopropellant propulsion system configurations and propellant manifolds generated by water hammer effects resulting from a priming event. This was accomplished through the development of a priming event experimental setup using distilled water as a propellant simulant for hydrazine. Multiple test elements were evaluated using different internal diameters, line lengths, manifold layouts, and flow control valves at atmospheric, subatmospheric, and low-pressure pretest pressure levels. The goals of the research were to determine the influence of restrictions in a liquid propulsion system, as well as the propellant manifold design, in the mitigation of the priming event maximum pressure levels. Based upon experimental results, it was determined that the internal diameter, line length, valve flow coefficient, and pretest pressure level all contributed to the pressure magnitude of the priming event. It was also observed that peak water hammer pressure levels might be significantly minimized and equally distributed throughout a propulsion system manifold using an inline cavitating venturi and manifold layout promoting free flow of the fluid, which was independent of the line geometry, the valve flow coefficient, and the valve opening response time.

Experimental determination of general characteristic of internal combustion engine using mobile test bench connected via Power Take-Off unit

The general characteristics of the engine include information about the regions of the engine’s operating area that are most efficient, where specific fuel consumption reaches the smallest values. Economic operation based on those characteristics can contribute to a significant reduction of fuel consumption and consequently less pollutant emissions and lower costs. The paper presents an experimental method of determination of general characteristic of internal combustion engine mounted in a truck chassis. Experimental tests focus on low torque and engine speed range, which is observed during operation of the body Refuse Collection Vehicle. To conduct the measurements, the specially designed test bench was used. The collected data from two engines was processed applying machine learning methods, which were described and compared to obtain best regression model. Determined general characteristic was used to evaluate fuel consumption in a time period of variable engine load. Finally, simulated total fuel used for both engines in different engine speeds and load were compared. Results show significant differences in total fuel consumption depend on engine speed, thus it is an evidence that there is a large field to improvement in propulsion system configuration.

Methodology for the Assessment of Distributed Propulsion Configurations with Boundary Layer Ingestion Using the Discretized Miller Approach

The growing global environmental awareness has motivated the search for more fuel-efficient aircraft propulsion systems. In this context, a configuration based on distributed propulsion with Boundary Layer Ingestion (BLI) has been found to present potential performance benefits. The concept has been documented and explored extensively during the last few years and various aerodynamic integration issues, such as: high levels of distortion and low intake pressure recovery; have been identified as factors that may be detrimental in realizing the technology full potential. Parametric and parallel compressor (PC) approaches have been used to assess the effect of these aerodynamic issues on propulsors fan performance. However, in the context of BLI, these tools are unable to assess the effects of combined radial and circumferential distortion that are present. In order to assess the combined distortion patterns and the effects of distortion at component and system levels, this study uses a novel method based on semi-empirical correlations denominated the Discretized Miller (DM) approach. This method was developed for BLI systems previously by the author, and it is now incorporated into the propulsor performance method to assess the effects of the combined radial and circumferential distortion patterns. The performance analysis, undertaken at a component and system level, aims to assess several propulsion architectures, using Thrust Specific Fuel Consumption (TSFC) as figure of merit. To define the suitability of the distributed propulsor array in this study, an airframe layout based on the N3-X aircraft concept and High Temperature Superconducting (HTS) electric motor capabilities were assumed. The key contribution of this study is to enable the introduction of the concept of thrust split between energy source and propulsion system in the system analysis, and thereby, allows the assessment of its effects on different propulsion system layouts, while considering the BLI induced distortion. The results obtained with this alternative performance method showed that BLI reduces the fan efficiency of a conventional fan by approximately 2%, whilst corroborating the TSFC trends observed in previous studies. The study also indicates that when sizing effects of propulsors and core-engines were neglected, a propulsion system configuration with 75% thrust split was found optimum.

Thermodynamic and Environmental Impact Assessment of NH3 Diesel–Fueled Locomotive Configurations for Clean Rail Transportation

AbstractAmmonia (NH3) is considered as a combustion fuel, hydrogen carrier, and heat-recovery and working fluid within locomotive propulsion-system configurations. Thermodynamic and environmental a...

An Empirical Study of Overlapping Rotor Interference for a Small Unmanned Aircraft Propulsion System

The majority of research into full-sized helicopter overlapping propulsion systems involves co-axial setups (fully overlapped). Partially overlapping rotor setups (tandem, multirotor) have received less attention, and empirical data produced over the years is limited. The increase in demand for compact small unmanned aircraft has exposed the need for empirical investigations of overlapping propulsion systems at a small scale (Reynolds Number < 250,000). Rotor-to-rotor interference at the static state in various overlapping propulsion system configurations was empirically measured using off the shelf T-Motor 16 inch × 5.4 inch rotors. A purpose-built test rig was manufactured allowing various overlapping rotor configurations to be tested. First, single rotor data was gathered, then performance measurements were taken at different thrust and tip speeds on a range of overlap configurations. The studies were conducted in a system torque balance mode. Overlapping rotor performance was compared to an isolated dual rotor propulsion system revealing interference factors which were compared to the momentum theory. Tests revealed that in the co-axial torque-balanced propulsion system the upper rotor outperforms the lower rotor at axial separation ratios between 0.05 and 0.85. Additionally, in the same region, thrust sharing between the two rotors changed by 21%; the upper rotor produced more thrust than the lower rotor at all times. Peak performance was recorded as a 22% efficiency loss when the axial separation ratio was greater than 0.25. The performance of a co-axial torque-balanced system reached a 27% efficiency loss when the axial separation ratio was equal to 0.05. The co-axial system swirl recovery effect was recorded to have a 4% efficiency gain in the axial separation ratio region between 0.05 and 0.85. The smallest efficiency loss (3%) was recorded when the rotor separation ratio was between 0.95 and 1 (axial separation ratio was kept at 0.05). Tests conducted at a rotor separation ratio of 0.85 showed that the efficiency loss decreased when the axial separation ratio was greater than 0.25. The lower rotor outperformed the upper rotor in the rotor separation ratio region from 0.95 to 1 (axial separation ratio was kept at 0.05) at an overall system thrust of 8 N, and matched the upper rotor performance at the tested overall thrust of 15 N.

항공기 시스템 레벨 열관리 기술개발 동향

ABSTRACT Modern aircraft is facing the increase of power demands and thermal challenges. In accordance with the application of more electric technology and advanced mission requirement, aircraft system requires increase of power generation and it cause increase of internal heat generation. Simultaneously, restrictions have significantly been imposed to the thermal management system. Modern aircraft must maintain low radar observability and infra-red signature. In addition, new composite aircraft skins have reduced the amount of heat that can be rejected to the environment. The combination of these characteristics has increased the challenges faced by thermal management. In order to mitigate the thermal challenges, the concept of system level thermal management should be applied and new modeling and simulation tools need to be developed. To develop and utilize system level thermal management technology, three key points are considered. Firstly, the performance changes of subsystems and components must be assessed at an integrated thermal system. It is because that each subsystem and component interacts with other subsystems or components and it can directly effects on overall system performance. Secondly, system level thermal management requirements and solutions must be evaluated early in conceptual design process as vehicle and propulsion system configuration decisions are being made. Finally, new component level thermal management technologies must focus on reducing heat generation and increasing the availability of heat sinks.Key Words : System Level Thermal Management, Fuel Thermal Management System, Adaptive Power Thermal Management System, Heat Load, Modeling and Simulation

Aerodynamic Performance of Blended Wing Body Aircraft with Distributed Propulsion

A 350-passenger BWB with a distributed propulsion system configuration is carried out and its aerodynamic performance in cruising and taking off are analyzed and discussed. It is shown from computation that the integrated configuration has a commendable aerodynamic performance in cruising and taking off. The cruise lift to drag ratio is reach to 24.0 in cruising. The ingestion effect of the propulsion system leads to a high lift at a low speed. The maximum lift coefficient CLmax is 1.62 when α=20° in taking off. In addition, the ingestion also delays the flow separation on the upper surface of center body, which contributes to a well stall performance of the configuration at large angle of attack.