Preliminary Design Model Research Articles

Development of a low-cost flutter test bed with an EPS foam model for preliminary wing design

This paper discusses a novel, low-cost approach for the design and testing of a flutter test article made out of expanded polystyrene (EPS) foam. The low mass of this test article makes it especially suitable for serving as a test bed for similar low structure-to-fluid mass ratio wing configurations, though it could just as easily be used as the first step in the flutter testing of any structure with complex shape and mechanical properties. The material properties of EPS foam were tested using two different approaches: a 3-point bending test based on ASTM Standards for cellular materials and a new finite element model updating approach that used experimental data collected from simple ground vibration tests (GVT). It was found that the second approach provided material properties that were the most representative of the behavior of the specimen under flutter loads. That information was then used in a computational aeroelastic flutter model of the EPS foam wing. Wind tunnel flutter tests were performed for the EPS foam model. The computational frequency domain decomposition (CFDD) method was used to identify modal parameters and the damping trend extrapolating method was used to predict the critical flutter speed from pre-flutter experimental data. The flutter results from the aeroelastic model were in good agreement with the test data.

Electromagnetic analysis of HCCB TBM-set during plasma major disruptions

Electromagnetic (EM) loads (i.e., Lorentz and Maxwell loads) on the Chinese (CN) Helium-Cooled Ceramic Breeder (HCCB) Test Blanket Module set (TBM-set) as well as on the installation Frame are numerically estimated using the ANSYS software. ITER Global Model (IGM) based on the edge-flux formulation is utilized in EM analysis. The current Preliminary Design (PD) model of HCCB TBM-set is taken into account. Four typical plasma Major Disruptions (MDs) are considered in accordance with the system load specifications. It is discovered that both kinds of EM loads are dominated by the radial component. The MD_DW_III is the worst case in terms of Lorentz loads, while the considered MDs have almost the same maximum Maxwell loads which appear under the condition of plasma start of burn. Regarding the EM loads on two TBMs, the Maxwell Force (MF) is much larger compared with the Lorentz Force (LF), however the Maxwell Torque (MT) is far smaller than the maximum Lorentz Torque (LT). The obtained results will be applied in corresponding structural analysis to ensure the integrity of HCCB TBM-set in the further work.

Early-Stage Radiation Safety Analysis for the Spallation Neutron Source Second Target Station Bunker Operations

The Second Target Station project at Oak Ridge National Laboratory will develop a cold neutron source to meet growing experimental needs. This paper describes calculations of the residual dose rates associated with the monolith shield plug and the beamline bunker, two key conventional operations and radiation safety features. While neutron production is active, the instrument hall outside the bunker must be generally accessible with dose rates of less than 0.25 mrem/h. When neutron production is halted, the bunker must be accessible for hands-on maintenance operations. These two requirements form the cause for the assessments reported herein of residual dose rates caused by the monolith shield plug and residual dose rates in the bunker. The monolith shield plug was shown to not produce significant dose rates inside the bunker after a 20-year lifetime, and the residual dose rates inside the bunker for the case of an operating beamline were shown to reasonably allow for hands-on maintenance. These calculations are based on preliminary design models of the relevant systems. Additionally, an example showing the significance of considering neutron supermirror physics in transport calculations that track nuclide production and destruction rates to produce gamma sources for residual dose rate calculations is included. The example shows that if neutron supermirror physics is not considered, dose rate fields may be significantly underpredicted.

A novel collaborative decision-making method based on generalized abductive learning for resolving design conflicts

In complex product design, lots of time and resources are consumed to choose a preference-based compromise decision from non-inferior preliminary design models with multi-objective conflicts. However, since complex products involve intensive multi-domain knowledge, preference is not only a comprehensive representation of objective data and subjective knowledge but also characterized by fuzzy and uncertain. In recent years, enormous challenges are involved in the design process, within the increasing complexity of preference. This article mainly proposes a novel decision-making method based on generalized abductive learning (G-ABL) to achieve autonomous and efficient decision-making driven by data and knowledge collaboratively. The proposed G-ABL framework, containing three cores: classifier, abductive kernel, and abductive machine, supports preference integration from data and fuzzy knowledge. In particular, a subtle improvement is presented for WK-means based on the entropy weight method (EWM) to address the local static weight problem caused by the fixed data preferences as the decision set is locally invariant. Furthermore, fuzzy comprehensive evaluation (FCE) and Pearson correlation are adopted to quantify domain knowledge and obtain abducted labels. Multi-objective weighted calculations are utilized only to label and compare solutions in the final decision set. Finally, an engineering application is provided to verify the effectiveness of the proposed method, and the superiority of which is illustrated by comparative analysis.

Refined MagSail thrust model for preliminary mission design and trajectory optimization

A magnetic sail is an advanced propellantless propulsion system concept for deep space missions, proposed by Dana Andrews and Robert Zubrin about 30 years ago. The thrust is generated by the electromagnetic interaction between the solar wind charged particles and an artificial magnetic field obtained through a large current-carrying coil made of superconducting material. This paper discusses an up-to-date single-loop magnetic sail thrust model based on the numerical and experimental results obtained in the last decade. In particular, a particle model is initially used to evaluate the performance of a reference configuration in terms of thrust components in a body reference frame. Then, some scaling relationships are used to estimate the magnetic sail performance as a function of the design parameters. The proposed thrust model is used to analyze the minimum-time transfer problem between two circular and coplanar heliocentric orbits. Minimum flight times necessary to complete ephemeris-free Earth-Venus and Earth-Mars transfers are calculated as a function of the magnetic sail characteristic size in a parametric way.

Effect of blade number on the performance of centrifugal fan

The present-day energy crisis challenges the engineers to take careful steps in design of fans. Enhancing the performance of centrifugal fan through parametric analysis is one of the ways. Simulation of centrifugal fan is demonstrated by considering a preliminary design model of backward curved bladed impeller centrifugal having 11 blades (MD1) which is designed using theoretical concepts from fan handbooks to achieve an air capacity of 7 m3/s producing a total pressure at outlet of fan to be 2000 Pa while impeller running at 1500 RPM which is the industrial requirement. Solid model is created and simulation is performed to analyze the fluid flow using Computational Fluid Dynamics (CFD). Results of this preliminary model show that a total pressure of 1323.07 Pa at the outlet of fan is achieved with an efficiency of 50.82%. Need for improvement in performance and to the study of effect of blade number on the model has led to perform simulations by varying the number of blades of impeller to Z = 8, 10, 12, 14 while keeping all the parameters identical to the design point condition. Contour plots of flow and velocity vectors in the blade passages areas for different cases along with the total pressure and efficiency are compared. Assessment of these results shows that when blade number Z = 14, there is an increase in total pressure by 21.77% and efficiency by 5.74% in comparison with design point condition. The centrifugal fan is simulated successfully as the residuals shows good convergence of <10−5.

Developing a physics-informed and physics-penalized neural network model for preliminary design of multi-stage friction pendulum bearings

Over the last few decades, the field of base isolation systems has made significant strides forward by developing new systems to improve the behavior of isolated structures under moderate and severe seismic excitations. One of the most efficient systems is the multi-stage friction pendulum that can provide a wide range of effective pendula with various regimes to reach high energy dissipation capability. The difficulty in designing such bearing at the preliminary stage comes from the relatively long process of trials to select the parameters of each sliding surface in order to ensure that the required effective period, effective damping, and displacement capacities are met. Thus, the following study proposes a direct design approach relying on a physics-informed and physics-penalized neural network model to overcome this issue. Within the context of the analysis, a large dataset composed of over 35000 isolators that covers a wide range of properties of the recently developed generation of friction pendulum “Quintuple Friction Pendulum” was generated following the mechanics-driven approach and then utilized as the case study to test the reliability of suggested design strategy and capability of the proposed multi-output neural network method. Thereafter, the performance of the physics-informed and physics-penalized model was compared to a purely data-driven approach and a physics-informed one. Generally, the results have shown that the proposed model has considerable accuracy with a maximum MAPE of 4.89% for achieving the required QFP properties. Additionally, they showed that the presented method provides an effective way for rapidly designing a quintuple friction pendulum isolator.

Multi-Fidelity Combustor Design and Experimental Test for a Micro Gas Turbine System

A multi-fidelity micro combustor design approach is developed for a small-scale combined heat and power CHP system. The approach is characterised by the coupling of the developed preliminary design model using the combined method of 3D high-fidelity modelling and experimental testing. The integrated multi-physics schemes and their underlying interactions are initially provided. During the preliminary design phase, the rapid design exploration is achieved by the coupled reduced-order models, where the details of the combustion chamber layout, flow distributions, and burner geometry are defined as well as basic combustor performance. The high-fidelity modelling approach is then followed to provide insights into detailed flow and emission physics, which explores the effect of design parameters and optimises the design. The combustor is then fabricated and assembled in the MGT test bench. The experimental test is performed and indicates that the designed combustor is successfully implemented in the MGT system. The multi-physics models are then verified and validated against the test data. The details of refinement on lower-order models are given based on the insights acquired by high-fidelity methods. The shortage of conventional fossil fuels and the continued demand for energy supplies have led to the development of a micro-turbine system running renewable fuels. Numerical analysis is then carried out to assess the potential operation of biogas in terms of emission and performance. It produces less NOx emission but presents a flame stabilisation design challenge at lower methane content. The details of the strategy to address the flame stabilisation are also provided.

A Novel Concentrated-Winding Vernier Pseudo-Direct-Drive Permanent-Magnet Machine

The demand for low-speed (LS) and high-torque electrical machines is increasing in different applications. Previous research showed that dual-stator magnetically geared machines, such as Vernier pseudo-direct-drive machines (VPDDs), can have a high torque density and a high power factor. However, the size of their end-winding can affect heavily their torque density. Based on a distributed winding VPDD, we propose a concentrated-winding split-teeth VPDD (ST-VPDD), which can reduce the size of end-winding and output higher torque density. In this research, a model of the end-winding volume is given. Through preliminary design and finite element model (FEM) analysis, the torque density optimization has been performed to maximize the torque density. Taking the end-winding into account, there is a 93.8&#x0025; improvement for the torque density, compared to the VPDD, to reach 78.1 Nm/L. After adding a sleeve for mechanical stability, the ST-VPDD still gives a 68.7&#x0025; improvement compared to the VPDD.

A study of forming of thin-walled hemispheres by mandrel-free spinning of commercially pure aluminum tubes

Abstract The purpose of this research is to understand the effect of process parameters in multi-pass, mandrel-free, room-temperature tube-spinning, and in particular the role of axial feed-rate on the shape and thickness change when producing a hemisphere. This is tackled with a combination of experiments and analysis. The material of this study is heat-treated, commercially-pure aluminum (AA1070) tubes of 100 mm diameter. To produce the hemisphere, seven linear passes are selected. The spinning experiments are conducted for two tube thicknesses (2 mm and 3 mm) under three different axial feed-rates (2, 5, and 7.5 mm/rev.) and identical radial feed-rate (5 mm/pass). It is found that decreasing the axial feed-rate generates less spatial variation in the final thickness, while also making the process slower. During every experiment, the tube wrinkles axially. The experiments are interrupted after different spinning passes, and the shape and thickness are measured. Three different finite element models are described, using axisymmetric, shell and solid elements, respectively. Comparing them to the experiments shows that the computationally-efficient axisymmetric model gives reasonable shape and thickness predictions. The shell element model tends to overpredict the shape and thickness evolution during spinning, while being about 250 times slower. Finally, the solid element model provides good agreement with the experiments across the board, while being only 2 times slower than the shell element one. Hence it is recommended for industrial practice to use the axisymmetric model for preliminary process design (i.e., selection of toolpath and process parameters) and then to refine these selections with the solid element model.

Improvement Model for the Proposal Accuracy of Security System Design at Industrial Facilities

The research develops an improvement model for industrial preliminary security system design (PSSD) projects at an engineering design company (EDC). The improvement model’s aim is to increase the accuracy of preliminary design Material Take-Off (MTOs) lists to reduce their non-compliance rate by clients in comparison to as-built design MTOs. The EDC’s design requirements allow an estimation error range of ±15% between preliminary design quantities and final as-built material quantities and equipment types/specifications. Also known as bills of quantity, the MTOs of PSSD projects at the EDC are investigated because their preliminary design error (PDE) rates exceed the 15% acceptable error margin that factor into a lower overall quality performance score. The study analyzes the entire population of noncompliant (NC) PSSD projects at the EDC consisting of 13 projects. The improvement model comprises of the procedural application of seven developed solutions during preliminary engineering design to mitigate critical errors identified from analyzed non-compliant PSSD projects. The application of solutions reduces the quantities of NC PSSD projects from thirteen to eight across all security project classifications. This indicates a 38.46% reduction in NC PSSD projects.

Autonomous Underwater Vehicle Powered by Direct Methanol Fuel Cell-Based Power Plants: A Quick Preliminary Design Model

Investigation, conservation, and exploitation of seas require platforms capable of accomplishing a wide variety of missions in harsh environments with restricted human intervention for long periods of time. Autonomous Underwater Vehicles (AUVs) are excellent tools for carrying out these missions due to their versatility and ability to access remote sites. However, despite the improvement of their capabilities, their development is not devoid of challenges. Endurance, among others, such as underwater communications or autonomy, is still a pending subject. Current battery-based solutions do not offer sufficient endurance and innovative power plants with higher energy content are needed. This work studies the advantages, in terms of endurance, of using a power plant based on Direct Methanol Fuel Cells (DMFCs) to power AUVs. In order to accomplish this, a multi-objective optimization tool that makes use of a genetic algorithm was developed. This tool allows quick preliminary design of AUVs with a DMFC-based power plant, complying with a user-defined payload, operation profile, and restrictions. Six designs based on a real AUV model were studied, and endurance values up to 2 times longer than the corresponding reference AUV were obtained. These results support the benefits of using DMFCs to power AUVs to increase their endurance.

Off-design performance comparison of single-stage axial turbines using CO2 and zeotropic mixture for low-temperature heat source

Organic Rankine cycle (ORC) and transcritical CO2 power cycle are two effective methods for low-grade energy utilization. Turbo-expanders of these power cycles need to maintain a high efficiency under both design and off-design conditions. In this study, the performances of two single-stage axial turbines are compared using a zeotropic mixture and CO2 as working fluids for a low-temperature geothermal source. First, a preliminary design model is established based on the mean line method. Subsequently, the input conditions for each turbine are determined and the performances of the two turbines are analyzed under the design condition. Then, the operation characteristics of the two turbines are investigated under various off-design conditions and the extent of the turbine efficiency reduction is evaluated. In addition, the effects of composition variation for the ORC turbine and the inlet temperature of the CO2 turbine are estimated respectively. The results indicate that the efficiency of the CO2 turbine is 0.875 at the design point, which is slightly higher than that of the ORC turbine as 0.864. The geometric size of the CO2 turbine is smaller than the ORC turbine apparently. The CO2 turbine has a higher efficiency over the entire operation range compared with the ORC turbine. Under the off-design conditions, the variation magnitude of the efficiency for the CO2 turbine is apparently less than that of the ORC turbine due to a lower pressure ratio and a larger flow rate.

Liquid Solar Fuel – Liquid hydrocarbons from solar energy and biomass

The Liquid Solar Fuel (LSF) concept aims to provide renewable-energy-based fuels like synthetic Diesel and Kerosene for long-distance transport via trucks, ships and airplanes and for remote machinery. The purpose of this paper is to present a preliminary design and performance model of a small scale plant with a rated production capacity of 100 barrels per day. First technical and economic performance estimates suggest that an achievable process efficiency around 50% and a product cost of ca. 1 US$/liter for large scale units in the medium term future can be attractive when compared to similar processes like power-to-liquid or biomass-to-liquid.A key attribute of the LSF concept is to maximize efficiency of all physical and chemical processes involved by continuous full-load operation of the synthesis process avoiding any transients, and by integrating and recycling all involved energy and material flows. How to achieve this in an effective way in spite of mainly using variable renewable energy from sunshine and wind for power supply is a key finding of the analysis, significantly reducing the need for major storage facilities for hydrogen and other involved substances.A major implication of the study is that carbon-free production of synthetic liquid hydrocarbon fuels is possible with present state-of-the-art technologies and can be efficient and affordable under appropriate frame conditions that exist in many parts of the world.The analysis has been made in the frame of internal activities of the Department of Systems Analysis and Technology Assessment at the German Aerospace Center (DLR) in Stuttgart, Germany, since 2008, and had the goal to identify sustainable solutions for future long-distance transport fuels. The model analysis provides technical and economic performance estimates of a first prototype.

Evaluation of assemblability during aero engine preliminary design

Despite the constant growth of global air traffic, the competition amongst airlines and their aviation supply chains intensifies. In the future, stricter environmental regulations as well as economic goals will only be met by new aircrafts and aero engines. In order to evaluate the life-cycle related cost at an early stage in the product design process, it is essential to assess the manufacturability and assemblability during preliminary design. Through the assessment of assemblability, major cost drivers can be identified in order to optimize the overall production cost. In this paper, a method to assess the assemblability of different preliminary design variants is introduced. To achieve this, 2D cross sections of actual aero engines are translated into 3D preliminary design models. Finally, an evaluation of the assemblability of different design variants of low pressure turbine modules is conducted.

Finite element based N-Port model for preliminary design of multibody systems

This article presents and validates a general framework to build a linear dynamic Finite Element-based model of large flexible structures for integrated Control/Structure design. An extension of the Two-Input Two-Output Port (TITOP) approach is here developed. The authors had already proposed such framework for simple beam-like structures: each beam was considered as a TITOP sub-system that could be interconnected to another beam thanks to the ports. The present work studies bodies with multiple attaching points by allowing complex interconnections among several sub-structures in tree-like assembly. The TITOP approach is extended to generate NINOP (N-Input N-Output Port) models. A Matlab toolbox is developed integrating beam and bending plate elements. In particular a NINOP formulation of bending plates is proposed to solve analytic two-dimensional problems. The computation of NINOP models using the outputs of a MSC/Nastran modal analysis is also investigated in order to directly use the results provided by a commercial finite element software. The main advantage of this tool is to provide a model of a multibody system under the form of a block diagram with a minimal number of states. This model is easy to operate for preliminary design and control. An illustrative example highlights the potential of the proposed approach: the synthesis of the dynamical model of a spacecraft with two deployable and flexible solar arrays.

Flight dynamics model for preliminary design of PrandtlPlane wing configuration with sizing of the control surfaces

This paper deals with the evaluation of the flight dynamics response of aircraft with a PrandtlPlane configuration by means of simple models to be used during the preliminary design. The study is completed by a method for an initial sizing of the elevators and the ailerons (positioned on both the front and the rear wing) in order to achieve adequate handling qualities. The flight dynamics model considers the rigid aircraft, the steady aerodynamics, and separating the longitudinal and the lateral-directional motions. The force derivatives are extrapolated through a VLM solver whose the reliability of the results has been proven. The methods have been applied on the IDINTOS aircraft with the conclusion that we obtain a proper longitudinal dynamic response with a reduced Margin of Stability because of the very high values of the aerodynamic damping Mq and the pitch stiffness Malpha.

Combined Turbine and Cycle Optimization for Organic Rankine Cycle Power Systems—Part A: Turbine Model

Axial-flow turbines represent a well-established technology for a wide variety of power generation systems. Compactness, flexibility, reliability and high efficiency have been key factors for the extensive use of axial turbines in conventional power plants and, in the last decades, in organic Rankine cycle power systems. In this two-part paper, an overall cycle model and a model of an axial turbine were combined in order to provide a comprehensive preliminary design of the organic Rankine cycle unit, taking into account both cycle and turbine optimal designs. Part A presents the preliminary turbine design model, the details of the validation and a sensitivity analysis on the main parameters, in order to minimize the number of decision variables in the subsequent turbine design optimization. Part B analyzes the application of the combined turbine and cycle designs on a selected case study, which was performed in order to show the advantages of the adopted methodology. Part A presents a one-dimensional turbine model and the results of the validation using two experimental test cases from literature. The first case is a subsonic turbine operated with air and investigated at the University of Hannover. The second case is a small, supersonic turbine operated with an organic fluid and investigated by Verneau. In the first case, the results of the turbine model are also compared to those obtained using computational fluid dynamics simulations. The results of the validation suggest that the model can predict values of efficiency within ± 1.3%-points, which is in agreement with the reliability of classic turbine loss models such as the Craig and Cox correlations used in the present study. Values similar to computational fluid dynamics simulations at the midspan were obtained in the first case of validation. Discrepancy below 12 % was obtained in the estimation of the flow velocities and turbine geometry. The values are considered to be within a reasonable range for a preliminary design tool. The sensitivity analysis on the turbine model suggests that two of twelve decision variables of the model can be disregarded, thus further reducing the computational requirements of the optimization.

New actuator disk model for propeller-aircraft computation

There is a growing interest in propellers for transport aircraft as well as regional airliners from the viewpoint of energy saving. An important consideration for utilizing a propeller propulsion system on aircraft is the aerodynamic interaction between the propeller slipstream and other aerodynamic surfaces. It is therefore necessary to use a simplified but relatively accurate tool for propeller modeling, with the widely used actuator disk model. The advantage of this model is that it is easy to use and inexpensive in terms of computation time required. In addition, it also produces acceptable results. In this study, a new regionalized actuator disk model was utilized in the analysis of propeller slipstream interference effects on a real four-propeller aircraft. The results are compared with the cases of inactive actuator disks, which shows that the propeller slipstream causes an increase in the lift and drag coefficients. An evident yawing effect caused by the rotating slipstream was noticed, which should be taken into account in the design phase. The regionalized actuator disk model is evaluated as a fast and relatively accurate model for propeller preliminary design.

Building information modeling-based integration of MEP layout designs and constructability

Abstract Building information modeling (BIM) has demonstrated its advantages in improving a mechanical, electrical and plumbing (MEP) layout in the design stage. Unfortunately, BIM applications normally stop prior to the construction stage. The MEP layout design may no longer fit properly during the installation process when there are as-built deviations between structures and the MEP layout. The purpose of this paper is to develop a practical BIM framework for integrating the MEP layout from preliminary design to construction stage. In this framework, BIM models were categorized into five levels of details: 3D MEP preliminary design model, 3D MEP detailed design model, 3D MEP construction design model, MEP construction model and MEP prefabrication model. Four types of coordination steps have been formulated to solve the design and constructability issues. A case study was adopted to validate the practical BIM framework. The results are very encouraging and demonstrate the significant value of the proposed BIM approach. In addition, one issue of collision detection is discussed because 78% collisions are ineffective when using the BIM tools for collision detection; and a significant number of effective collisions (102 collisions) are still detected by the designers and contractors manually. Ultimately, the research renders a practical insight into improving the MEP design and constructability using the developed BIM framework.