Hypersonic dynamic stability of wave riders

2017 ◽  
Vol 89 (3) ◽  
pp. 434-443
Author(s):  
Mahmood Khalid ◽  
Khalid A. Juhany
Keyword(s):  
Dynamic Stability ◽  
Design Method ◽  
Static Stability ◽  
Small Disturbance ◽  
Similarity Parameter ◽  
Content Type ◽  
Flat Surfaces ◽  
Stability Derivatives ◽  
Cone Type ◽  
Half Cone

Purpose The purpose of this paper is to obtain close form expressions for the dynamic stability of conical wave riders with flat surfaces which could be equipped with lifting surfaces on its plain flat surface. Numerical simulation would require very large meshes to resolve flows at subscale level and the experimental evaluations would be equally difficult, requiring expensive measurement facilities with challenging procedures to secure such vehicles in confined test sections to obtain satisfactory wind on and wind off oscillations. Design/methodology/approach The design method uses appropriate pressure fields using small disturbance theory, which, in turn, is perturbed using the unsteady shock expansion theory to recover suitable expressions for the dynamic stability behaviour. Findings It was observed that the dynamic stability of the standard half-cone-type wave riders with flat upper surfaces deteriorates with the axis position measured from the pointed apex reaching a minimum at around x/co = 0.666. The half-cone wave rider with flat upper surfaces is dynamically less stable than a pure cone. Research limitations/implications The method is typically less accurate when the similarity parameter M∞θ ≤ 1 = 1 or if the angle of attack is not small. Practical implications With renewed interest in hypersonic, future hypersonically would be designed as fast lifting bodies whose shapes would be close to the configurations of hypersonic wave riders, especially if they are designed to operate at upper atmosphere altitudes. Originality/value The analytic approach outlined in this paper for the evaluation of dynamic and static stability derivatives is original, drawing from the strengths of the small disturbance theory and shock expansion techniques. The method is particularly important, as there are no reported theoretical, numerical or experimental results in the literature.

Aerodynamics analysis of the main rotor influence on the static stability of the gyroplane

2017 ◽  
Vol 89 (5) ◽  
pp. 663-670 ◽  
Author(s):  
Marcin Figat
Keyword(s):  
Dynamic Stability ◽  
Static Stability ◽  
Main Rotor ◽  
Aerodynamic Coefficients ◽  
Content Type ◽  
Flight Condition ◽  
Configuration Change ◽  
Stability Derivatives ◽  
The Impact ◽  
Derivatives Of

Purpose This paper aims to present the results of aerodynamic calculation of impact the main rotor on the fuselage and the tail of a light gyroplane. This kind of vehicle is a type of rotorcraft which uses a non-powered rotor in autorotation to develop lift and engine-powered propeller to provide the thrust. Both of them disturb the flow around the gyroplane body (gyroplane fuselage and tail) and influence on its static stability. The main goal of the presented research was to find the magnitude of this influence. To measure this effect, the main stability derivatives changes of gyroplane body were investigated. Design/methodology/approach The CFD analysis of the complete gyroplane was made. Computation was performed for the model of gyroplane which was equipped with the two sub-models of the main rotor and the engine-powered propeller. Both of them were modelled as the actuator discs. This method allows to compute the aerodynamic impact of rotating components on the gyroplane body. All aerodynamic analysis was made by the MGAERO software. The numerical code of the software bases on the Euler flow model. Next, the resulting aerodynamic coefficients were used to calculate the most important stability derivatives of the gyroplane body. Findings The result obtained by computation presents the change in the most important aerodynamic coefficients and stability derivatives of the gyroplane body caused by the impact of its main rotor. Moreover, the result includes the change of the aerodynamic coefficients and stability derivatives caused by change of the main rotor configuration (change of rotation rate and angle of incidence) and change of the flight condition (gyroplane angle of attack sideslip angle and flight speed). Practical implications Analysis of the main rotor impact will be very useful for evaluation of dynamic stability of the light gyroplane. Moreover, the results will be helpful to design the horizontal and vertical tail for the light gyroplane. Originality/value This paper presents the method of the numerical analysis of the static stability of the light gyroplane’s body. The results of analysis present the impact of disturbance generated by the rotating main rotor on the static stability of the gyroplane body. Moreover, the impact of the main rotor configuration change and the flight condition change on the static stability were investigated too. The evaluation of the gyroplane’s body static stability was made by the stability derivatives. The methodology and obtained result will be very useful for analysis of the dynamic stability of the light gyroplanes. Moreover, the results will be helpful during design the main components of the gyroplane like vertical and horizontal tail.

scholarly journals A numerical study into the longitudinal dynamic stability of the tailless aircraft

2019 ◽  
Vol 91 (3) ◽  
pp. 428-436 ◽  
Author(s):  
Agnieszka Kwiek
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Numerical Study ◽  
Aircraft Design ◽  
Content Type ◽  
Preliminary Stage ◽  
Longitudinal Dynamic ◽  
Stability Derivatives ◽  
The Impact ◽  
Tailless Aircraft

Purpose The purpose of this research is a study into a mathematical approach of a tailless aircraft dynamic stability analysis. This research is focused on investigation of influence of elevons (elevator) on stability derivatives and consequently on the aircraft longitudinal dynamic stability. The main research question is to determine whether this impact should be taken into account on the conceptual and preliminary stage of the analysis of the longitudinal dynamic stability. Design/methodology/approach Aerodynamic coefficients and longitudinal stability derivatives were computed by Panukl (panel methods). The analysis of the dynamic stability of the tailless aircraft was made by the Matlab code and SDSA package. Findings The main result of the research is a comparison of the dynamic stability of the tailless aircraft for different approaches, with and without the impact of elevator deflection on the trim drag and stability derivatives. Research limitations/implications This paper presents research that mostly should be considered on the preliminary stage of aircraft design and dynamic stability analysis. The impact of elevons deflection on the aircraft moment of inertia has been omitted. Practical implications The results of this research will be useful for the further design of small tailless unmanned aerial vehicles (UAVs). Originality/value This research reveals that in case of the analysis of small tailless UAVs, the impact of elevons deflection on stability derivatives is bigger than the impact of a Mach number. This impact should be taken into consideration, especially for a phugoid mode.

An angle-changeable tracked robot with human-robot interaction in unstructured environments

2020 ◽  
Vol 40 (4) ◽  
pp. 565-575
Author(s):  
Chengguo Zong ◽  
Zhijian Ji ◽  
Junzhi Yu ◽  
Haisheng Yu
Keyword(s):  
Control System ◽  
Design Method ◽  
Static Stability ◽  
Human Robot Interaction ◽  
Working Environment ◽  
Robot Interaction ◽  
Content Type ◽  
Mechanical Structure ◽  
Rugged Terrain ◽  
Interaction Control

Purpose The purpose of this paper is to study the adaptability of the tracked robot in complex working environment. It proposes an angle-changeable tracked robot with human–robot interaction in unstructured environment. The study aims to present the mechanical structure and human–robot interaction control system of the tracked robot and analyze the static stability of the robot working in three terrains, i.e. rugged terrain, sloped terrain and stairs. Design/methodology/approach The paper presents the mechanical structure and human–robot interaction control system of the tracked robot. To prevent the detachment of the tracks during obstacle navigation, a new type of passively adaptive device based on the relationship between the track’s variable angle and the forces is presented. Then three types of rough terrain are chosen to analyze the static stability of the tracked robot, i.e. rugged terrain, sloped terrain and stairs. Findings This paper provides the design method of the tracked robot. Owing to its appropriate dimensions, good mass distribution and limited velocity, the tracked robot remains stable on the complex terrains. The experimental results verify the effectiveness of the design method. Originality/value The theoretical analysis of this paper provides basic reference for the structural design of tracked robots.

Stability analysis of the experimental airplane powered by a pulsejet engine

2019 ◽  
Vol 91 (6) ◽  
pp. 843-850 ◽  
Author(s):  
Katarzyna Pobikrowska ◽  
Tomasz Goetzendorf-Grabowski
Keyword(s):  
Stability Analysis ◽  
Eigenvalue Problem ◽  
Dynamic Stability ◽  
Design Methodology ◽  
Aircraft Design ◽  
Static Stability ◽  
Computational Time ◽  
Aerodynamic Coefficients ◽  
Content Type ◽  
Practical Implications

Purpose This paper aims to present stability analysis of a small pulsejet-powered airplane. This analysis is a part of a student project dedicated to designing an airplane to test valved pulsejet engine in flight conditions. Design/methodology/approach The panel method was chosen to compute the airplane’s aerodynamic coefficients and derivatives for various geometry configurations, as it provides accurate results in a short computational time. Also, the program (PANUKL) that was used allows frequent and easy changes of the geometry. The evaluation of dynamic stability was done using another program (SDSA) equipped with means to formulate and solve eigenvalue problem for various flight speeds. Findings As a result of calculations, some geometry corrections were established, such as an increase of the vertical stabilizer’s size and a new wing position. Resulting geometry provides satisfactory dynamic and static stability characteristics for all flight speeds. This conclusion was based on criteria given by MIL-F-8785C specifications. This paper presents the results of the first and the final configuration. Practical implications The results shown in this paper are necessary for the continuation of the project. The aircraft’s structure was being designed in the same time as the calculations described in this paper proceeded. With a few modifications to make up for the changes of external geometry, the structure will be ready to be built. Originality/value The idea to design an airplane specifically to test a pulsejet in flight is a unique one. Most RC pulsejet-powered constructions that can be heard of are modified versions of already existing models. What adds more to the value of the project is that it is being developed only by students. This allows them to learn various aspects of aircraft design and construction on a soon-to-be real object.

Aerodynamics analysis of rotor’s impact on the aircraft in the tandem wing configuration

2018 ◽  
Vol 92 (3) ◽  
pp. 336-344
Author(s):  
Marcin Figat
Keyword(s):  
Stability Margin ◽  
Static Stability ◽  
Complex Model ◽  
Numerical Code ◽  
Aerodynamic Coefficients ◽  
Sideslip Angle ◽  
Content Type ◽  
Aerodynamic Analysis ◽  
Stability Derivatives ◽  
The Impact

Purpose This paper aims to present the results of aerodynamic calculation of the aircraft in tandem wing configuration called VTOL. A presented vehicle combines the capabilities of the classic aircraft and helicopters. The aircraft is equipped with two pairs of tilt-rotors mounted on the tips of the front and the rear wing. The main goal of the presented research was to find the aerodynamic impact of both pairs of tilt-rotors on aerodynamic coefficients of the aircraft. Moreover, the rotors impact on the static stability of the aircraft was investigated too. Design/methodology/approach The CFD analysis was made for the complete aircraft in the tandem wing configuration. The computation was performed for the model of aircraft which was equipped with the four sub-models of the front and rear rotors. They were modeled as the actuator discs. This method allows for computing the aerodynamic impact of rotating components on the aircraft body. All aerodynamic analysis was made by the MGAERO software. The numerical code of the software was based on the Euler flow model. The used numerical method allows for the quick computation of very complex model of aircraft with a satisfied accuracy. Findings The result obtained by computation includes the aerodynamic coefficients which described the impact of the tilt rotors on the aircraft aerodynamic. The influence of the angle of attack, sideslip angle and the change of rotor tilt angle was investigated. Evaluation of the influence was made by the stability margin analysis and the selected stability derivatives computation. Practical implications Presented results could be very useful in the computation of dynamic stability of unconventional aircraft. Moreover, results could be helpful during designing the aircraft in the tandem wing configuration. Originality/value This paper presents the aerodynamic analysis of the unconventional configuration of the aircraft which combines the tandem wing feature with the tilt-rotor advantages. The impact of disturbance generated by the front and rear rotors on the flow around the aircraft was investigated. Moreover, the impact of rotors configuration on the aircraft static stability was found too.

A dynamic vertical shading optimisation to improve view, visual comfort and operational energy

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mahdi Valitabar ◽  
Mohammadjavad Mahdavinejad ◽  
Henry Skates ◽  
Peiman Pilechiha
Keyword(s):  
High Performance ◽  
Parametric Design ◽  
Design Method ◽  
Building Energy ◽  
Natural Light ◽  
Visual Comfort ◽  
Content Type ◽  
Operational Energy ◽  
Discomfort Glare ◽  
The Impact

PurposeThe aim of this paper is to present a parametric design method to generate optimum adaptive facades regarding occupants' comfort and building energy criteria. According to the literature review, the following questions have arisen to address the research gaps: Is it possible to have the outside view throughout the whole year without discomfort glare by utilising adaptive solar facades (ASFs)? How can architects integrate both view quality and quantity into ASF design? What is the impact of dynamic vertical shading systems mounted on south facades on the outside view, occupants' visual comfort and operational energy? How can we evaluate the view quantity through multi-layer shading systems?Design/methodology/approachIn recent years, there is a surge in demand for fully glazed buildings, motivating both architects and scholars to explore novel ideas for designing adaptive solar facades. Nevertheless, the view performance of such systems has not been fully explored especially when it comes to the effect of dynamic vertical shading systems mounted on south facades. This fact clarifies the need to conduct more research in this field by taking into account the window view and natural light. Consequently, a simulation research is carried out to investigate the impact of a dynamic shading system with three vertical slats used on the south facade of a single office room located in Tehran, on both view quality and quantity, visual comfort and operational energy. The research attempts to reach a balance between the occupant's requirements and building energy criteria through a multi-objective optimisation. The distinctive feature of the proposed method is generating some optimum shading which could only cover the essential parts of the window area. It was detected from the simulation results that the usage of a dynamic vertical shading system with multi slats for south facades compared to common Venetian blinds can firstly, provide four times more view quantity. Secondly, the view quality is significantly improved through enabling occupants to enjoy the sky layer the entire year. Finally, twice more operational energy can be saved while more natural light can enter the indoor environment without glare. The final outcome of this research contributes toward designing high-performance adaptive solar facades.FindingsThis paper proposes a new metric to evaluate the view quantity through a multi-layer shading system. The proposed method makes it clear that the usage of dynamic vertical shading systems with multi-layers mounted on south facades can bring many benefits to both occupants and building energy criteria. The proposed method could (1) provide four times more view quantity; (2) improve view quality by enabling occupants to watch the sky layer throughout the whole year; (3) slash the operational energy by twice; (4) keep the daylight glare probability (DGP) value in the imperceptible range.Research limitations/implicationsThe research limitations that should be acknowledged are ignoring the impact of the adjacent building on sunlight reflection, which could cause discomfort glare issues. Another point regarding the limitations of the proposed optimisation method is the impact of vertical shading systems on users' visual interests. A field study ought to be conducted to determine which one could provide the more desirable outside view: a vertical or horizontal the view. Research on the view performance of ASFs, especially their impact on the quality of view, is sorely lacking.Originality/valueThis paper (1) analyses the performance of dynamic vertical shadings on south facades; (2) evaluates outside view through multi-layer shading systems; and (3) integrates both view quality and quantity into designing adaptive solar facades.

Transformation paths and influencing factors of tacit knowledge into explicit knowledge in real estate companies: a qualitative study

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Guodong Ni ◽  
Ziyao Zhang ◽  
Zhenmin Yuan ◽  
Haitao Huang ◽  
Na Xu ◽  
...  
Keyword(s):  
Knowledge Management ◽  
Real Estate ◽  
Tacit Knowledge ◽  
Influencing Factors ◽  
Explicit Knowledge ◽  
Design Method ◽  
Structured Interviews ◽  
Content Type ◽  
Knowledge Resources ◽  
Tacit Knowledge Management

PurposeThe purpose of this paper is to figure out the paths about transformation of tacit knowledge into explicit knowledge, i.e. tacit knowledge explicating (TKE) in real estate companies, and determine the influencing factors of TKE in Chinese real estate companies to enable enterprises make better use of their knowledge resources.Design/methodology/approachThe study adopted an exploratory design method using thematic analysis and grounded theory, and semi-structured interviews were conducted to collect data. The interviewees consisted of employees in different positions, who come from Chinese real estate companies with different ranking ranges and different knowledge management levels. Data collection was divided into two rounds for the identification of transformation paths and influencing factors.FindingsThis study has shown that 11 paths about TKE divided into solidified organization process and construction of organizational infrastructure go into effect within the real estate companies. Factors influencing TKE in real estate companies concern three main categories: organizational distal factors, contextual proximal factors and individual factors, including 21 subordinates in total. Furthermore, correlation between TKE paths and influencing factors is established.Research limitations/implicationsResearch results may lack generalizability due to the method adopted. Therefore, researchers are encouraged to verify the outcomes of this research.Practical implicationsThis research provides a new idea and solutions for the tacit knowledge management in real estate companies.Originality/valueTo the best of the authors’ knowledge, this study is the first to systematically identify paths and the influencing factors of TKE in real estate companies, contribute to the incipient but growing understanding of achievement of “tacit to explicit” and enrich the corporate tacit knowledge management literature.

A new jig-shape optimization method for the high aspect ratio wing

2018 ◽  
Vol 91 (1) ◽  
pp. 124-133
Author(s):  
Zhe Yuan ◽  
Shihui Huo ◽  
Jianting Ren
Keyword(s):  
Aspect Ratio ◽  
Shape Optimization ◽  
High Aspect Ratio ◽  
Optimization Design ◽  
Design Method ◽  
Aircraft Design ◽  
Optimization Method ◽  
Attack Angle ◽  
Structural Deformation ◽  
Content Type

Purpose Computational efficiency is always the major concern in aircraft design. The purpose of this research is to investigate an efficient jig-shape optimization design method. A new jig-shape optimization method is presented in the current study and its application on the high aspect ratio wing is discussed. Design/methodology/approach First, the effects of bending and torsion on aerodynamic distribution were discussed. The effect of bending deformation was equivalent to the change of attack angle through a new equivalent method. The equivalent attack angle showed a linear dependence on the quadratic function of bending. Then, a new jig-shape optimization method taking integrated structural deformation into account was proposed. The method was realized by four substeps: object decomposition, optimization design, inversion and evaluation. Findings After the new jig-shape optimization design, both aerodynamic distribution and structural configuration have satisfactory results. Meanwhile, the method takes both bending and torsion deformation into account. Practical implications The new jig-shape optimization method can be well used for the high aspect ratio wing. Originality/value The new method is an innovation based on the traditional single parameter design method. It is suitable for engineering application.

scholarly journals Multiscale, thermomechanical topology optimization of self-supporting cellular structures for porous injection molds

2019 ◽  
Vol 25 (9) ◽  
pp. 1482-1492
Author(s):  
Tong Wu ◽  
Andres Tovar
Keyword(s):  
Topology Optimization ◽  
Mechanical Performance ◽  
Mechanical Load ◽  
Design Method ◽  
Three Dimensional ◽  
Optimization Method ◽  
Cellular Structures ◽  
Injection Mold ◽  
Computationally Efficient ◽  
Content Type

Purpose This paper aims to establish a multiscale topology optimization method for the optimal design of non-periodic, self-supporting cellular structures subjected to thermo-mechanical loads. The result is a hierarchically complex design that is thermally efficient, mechanically stable and suitable for additive manufacturing (AM). Design/methodology/approach The proposed method seeks to maximize thermo-mechanical performance at the macroscale in a conceptual design while obtaining maximum shear modulus for each unit cell at the mesoscale. Then, the macroscale performance is re-estimated, and the mesoscale design is updated until the macroscale performance is satisfied. Findings A two-dimensional Messerschmitt Bolkow Bolhm (MBB) beam withstanding thermo-mechanical load is presented to illustrate the proposed design method. Furthermore, the method is implemented to optimize a three-dimensional injection mold, which is successfully prototyped using 420 stainless steel infiltrated with bronze. Originality/value By developing a computationally efficient and manufacturing friendly inverse homogenization approach, the novel multiscale design could generate porous molds which can save up to 30 per cent material compared to their solid counterpart without decreasing thermo-mechanical performance. Practical implications This study is a useful tool for the designer in molding industries to reduce the cost of the injection mold and take full advantage of AM.

A cradle-to-cradle analysis in the toner cartridge supply chain using fuzzy recycling production approach

2019 ◽  
Vol 30 (2) ◽  
pp. 329-345 ◽  
Author(s):  
Chun-Wei Lin ◽  
Shiou-Yun Jeng ◽  
Ming-Lang Tseng ◽  
Raymond Tan
Keyword(s):  
Evaluation System ◽  
Design Method ◽  
Environmental Law ◽  
Integrated Approach ◽  
Life Cycles ◽  
Green Product ◽  
Production Plan ◽  
Content Type ◽  
The Usa ◽  
Cradle To Cradle

Purpose The purpose of this paper is to develop an integrated approach for a green product cradle-to-cradle (C2C) fuzzy recycling production planning model. Design/methodology/approach This paper applies the failure mode and effects analysis technique and Taguchi experimental design method, develops a green product C2C performance evaluation system that considers the fuzzy impacts of environmental laws and regulations, green goodwill, and environmental efficiency of targeting countries, and decides both the optimal green production plan and estimated optimal life cycles. Findings This study compares the different degree of maturity in environmental regulations, and various recycling situations are simulated to demonstrate the successful applicability of the proposed model as well as the incentive policy for Taiwan, the USA and Bangladesh. Originality/value Previous studies failed both to develop a holistic recycling production plan which is able to consider both the optimal combination of recycled components used and final green products produced with the maximum total resultant sales profit and to consider the potential failure phenomenon of recycled components adopted in the final product. Furthermore, most prior studies ignored the influence of environmental law, goodwill of the product and the efficiency of recycling mechanism of the community.

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