Emerald | Aircraft Engineering and Aerospace Technology | Table of Contents http://www.emeraldinsight.com/0002-2667.htm Table of contents from the most recently published issue of Aircraft Engineering and Aerospace Technology Journal en-gb Tue, 29 Apr 2014 00:00:00 +0100 2013 Emerald Group Publishing Limited editorial@emeraldinsight.com support@emeraldinsight.com 60 Emerald | Aircraft Engineering and Aerospace Technology | Table of Contents http://www.emeraldinsight.com/common_assets/img/covers_journal/aeatcover.gif http://www.emeraldinsight.com/0002-2667.htm 120 157 Special issue devoted to second EASN workshop on flight physics and propulsion http://www.emeraldinsight.com/journals.htm?issn=0002-2667&volume=86&issue=3&articleid=17108078&show=abstract <strong>Abstract</strong><br /><br />Not available. Article literatinetwork@emeraldinsight.com (Thrassos Panidis) Tue, 29 Apr 2014 00:00:00 +0100 Flight Dynamics models used in different national and international projects http://www.emeraldinsight.com/journals.htm?issn=0002-2667&volume=86&issue=3&articleid=17108097&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - Aiming to demonstrate different computational models, data and stability results obtained in a wide number of projects of various aircraft –UAVs, general aviation and big passenger flying airliners in Blended Wing Body (BWB) configurations. Many details of modeling and computing are shown for unconventional configurations, namely for a BWB aircraft and for a tailless UAVs.<B>Design/methodology/approach</B> - Mathematical models for analysis of static and dynamic stability were built and investigated basing on equations of motion in the linearized form using the so-called ‘state variable’ model for a steady-state disturbed, generally asymmetric flight.<B>Findings</B> - Flight Dynamics models and associated computational procedures appeared to be useful both in a preliminary design phase and during the final assessment of the configuration at flight tests. It was also found that the difference between thresholds for static and dynamic stability conditions were equal to 9% of MAC in the case of BWB and 3% of MAC in the case of tailless UAV. <B>Practical implications</B> - Many useful information about aircraft dynamics can be easily obtained from computational analyses including time to half/double, periods of oscillation, undamped frequencies, damping ratio and many other. Stability analysis of different unconventional configurations will be easier and faster if an access to such configurations is available. <B>Originality/value</B> - This paper presents very efficient method of assessment the designing parameters, especially in an early stage of design process. In open literature there is a great number of data sets for classical configurations but it is hard to find anything for passenger BWB and tailless UAV. Stability computations are performed basing on equations of motion derived in the stability frame of reference fixed with one quarter of Mean Aerodynamic Chord (MAC). It can be considered as an original, not typical but very practical approach because values of stability and control derivatives do not change even if the centre of gravity is travelling. Article literatinetwork@emeraldinsight.com (Zdobyslaw Jan Goraj) Mon, 31 Mar 2014 00:00:00 +0100 Hybrid RANS-LES for active flow control http://www.emeraldinsight.com/journals.htm?issn=0002-2667&volume=86&issue=3&articleid=17108099&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - The work in this article presents numerical investigations of flow control with piezoelectric actuators on a backward facing step, and fluidic vortex generators on a NACA0015 aerofoil for the reattachment and separation control through the manipulation of the Reynolds stresses.<B>Design/methodology/approach</B> - The unsteady flow phenomena associated with both devices are simulated employing Spalart-Allmaras based hybrid RANS/LES models (DES, DDES and IDDES), using an in-house CFD solver. Results from these computations are compared with experimental observations enabling their reliable assessment through the detailed investigation of the Reynolds stresses and also the separation and reattachment.<B>Findings</B> - All the hybrid RANS/LES methods investigated in this article predict reasonable results for the BFS case, while only IDDES captures the separation point as measured in the experiments. The oscillating surface flow control method by piezoelectric actuators applied to the BFS case demonstrates that the Reynolds stresses in the controlled case decrease, and that a slightly nearer reattachment is achieved for the given actuation. The fluidic vortex generators on the surface of the NACA0015 case force the separated flow to fully reattach on the wing. Although skin friction is increased, there is a significant decrease in Reynolds stresses and an increase in lift to drag ratio.<B>Originality/value</B> - The value of this article lies in the assessment of the hybrid RANS/LES models in terms of separation and reattachment for the cases of the backward facing step and NACA0015 wing, and their further application in active flow control. Article literatinetwork@emeraldinsight.com (Wei Wang, Spiridon Siouris, Ning Qin) Wed, 09 Apr 2014 00:00:00 +0100 The potential application method of magnetic levitation technology – as a ground-based power – to assist the aircraft take-off and landing processes http://www.emeraldinsight.com/journals.htm?issn=0002-2667&volume=86&issue=3&articleid=17108107&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - - present the first year results of the EU supported GABRIEL project on the possible use of magnetic levitation technology to assist the aircraft take-off and landing. <B>Design/methodology/approach</B> - Developing a radically new technology is a complex task. It is based on the extensive expert analysis, the use of technology identification evaluation and selection methods, the principle of the design philosophies, and the development of the radically new technologies. <B>Findings</B> - A possible solution of using the magnetic levitation technology to assist the aircraft take-off and landing was developed and defined including several original ideas, as the cart - sledge concept, or the unconventional climb principle. <B>Research limitations/implications</B> - This is a typical "out-of-the-box" project, without limitations on the developing new principles, technologies, but it is working on the development of a possible solution within the predictable technical and technological envelopes.<B>Practical implications</B> - The developed concept should assess, whether magnetic levitation technology for the aircraft take-off and landing is feasible, cost effective and safe. <B>Originality/value</B> - The GABRIEL concept is the first concept for using the magnetic levitation technology to assist the take-off and landing processes related to the commercial civil aviation. Article literatinetwork@emeraldinsight.com (Jozsef Rohacs, Daniel Rohacs) Tue, 29 Apr 2014 00:00:00 +0100 A novel approach for trajectory tracking of UAVS http://www.emeraldinsight.com/journals.htm?issn=0002-2667&volume=86&issue=3&articleid=17108136&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - Research on unmanned aircraft is improving constantly the autonomous flight capabilities of these vehicles in order to provide performance needed to employ them in even more complex tasks. The UAV Path Planner (PP) plans the best path to perform the mission. This is a waypoint sequence that is uploaded on the Flight Management System (FMS) providing reference to the aircraft Guidance Navigation and Control System (GNCS). The UAV GNCS converts the waypoint sequence in guidance references for the Flight Control System (FCS) that in turn generates the command sequence needed to track the optimum path.<B>Design/methodology/approach</B> - A new Guidance System (GS) is presented in this paper, based on the graph search algorithm Kinematic A* (KA*). The GS is linked to a Nonlinear Model Predictive Control (NMPC) system that tracks the reference path, solving on-line (i.e. at each sampling time) a finite horizon (state horizon) open loop optimal control problem with Genetic Algorithm (GA). The GA finds the command sequence that minimizes the tracking error with respect to the reference path, driving the aircraft toward the desired trajectory. The same approach is also used to demonstrate the ability of the guidance laws to avoid the collision with static and dynamic obstacles.<B>Findings</B> - The tracking system proposed reflects the merits of NMPC, successfully accomplishing with the tasks. As a matter of fact good tracking performance is evidenced and effective control actions provide smooth and safe paths, both in nominal and off-nominal conditions.<B>Originality/value</B> - The GNCS presented in this paper reflects merits of the algorithms implemented in the GS and FCS. As a matter of fact these two units work efficiently together providing fast and effective control in order to avoid obstacles in flight and go back to the desired path. KA* was developed from graph search algorithms. Maintaining their simplicity but improving their search logics, it represents an interesting solution for online re-planning. The results show that the GS uploads the collision avoidance path continuously during flight and it obtains straight forward the reference variables for the FCS thanks to the KA* model. Article literatinetwork@emeraldinsight.com (Luca De Filippis, Giorgio Guglieri, Fulvia Quagliotti) Tue, 29 Apr 2014 00:00:00 +0100 Bolt-joint structural health monitoring by method of electromechanical impedance http://www.emeraldinsight.com/journals.htm?issn=0002-2667&volume=86&issue=3&articleid=17108142&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - Some problems of the electromechanical impedance (EMI), especially its applications for structural health monitoring (SHM) of aircraft bolt-joints and innovated approach of EMI prediction at loosening of bolt-joints are presented in the paper. <B>Design/methodology/approach</B> - Experimental study includes the results of full-scale test of the Mi-8 helicopter tail beam, particularly, its bolt-joints of a beam with others parts of structure. One of the connecting frames of tail beam was equipped by piezoelectric transducers (PZT) glued on the surface of the frame near the bolts. The bolts’ loosening was investigated by using of the EMI technology. In analytical study the 2D model of a constrained PZT is proposed. In contrast with existing model the modal decomposition analysis is used as an universal mean to express the dynamic properties and dynamic responses of both the transducer and the host structure. This approach together with the finite element modal analysis allows simulating of any complex system ‘PZT- host structure’. <B>Findings</B> - It was demonstrated that loosening of the bolt-joint produces a significant and statistically stable change of EMI metric. Presumably both the small shift of resonance frequencies and the EMI magnitude and resistance change is caused mainly by damping variation at the bolt-joint loosening. The bolt-joint of the MI-8 helicopter with the EMI measurement system was simulated by using of the developed 2D model. Simulation results satisfactory correspond to test. The developed 2D model can be easy transformed also to the 3D one.<B>Practical implications</B> - The results of research can be used for implementation in the structural health monitoring of bolt-joints and others aerospace structural components. <B>Originality/value</B> - The new experimental results on aircraft real bolt-joint were obtained Especially significant is the original 2D model of the electromechanical impedance, based on the modal decomposition method, which can significantly improve the accuracy and realistic description of the dynamic interaction between PZT and structure, as well as the dynamic response to the appearance of structural damage. Article literatinetwork@emeraldinsight.com (Igor Pavelko, Vitalijs Pavelko, Sergey Kuznetsov, Ilmars Ozolinsh) Tue, 29 Apr 2014 00:00:00 +0100 Experimental and numerical investigation of a swirl stabilized premixed methane/air flame http://www.emeraldinsight.com/journals.htm?issn=0002-2667&volume=86&issue=3&articleid=17108074&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - The purpose of this paper is to assess the validity of Weller's b-? flamelet model for practical swirl stabilized combustion applications.<B>Design/methodology/approach</B> - Swirl stabilized premixed flame behavior is investigated utilizing an atmospheric combustor test rig. Swirl number of the flow is 0.74 with a cold flow Reynolds number of 19400 based on the hydraulic diameter at the inlet pipe. Operating condition corresponds to an equivalence ratio of 0.7 at a thermal load of 20.4 kW. Reacting flow was seeded with TiO2 particles and velocity distribution at the center plane was measured utilizing PIV technique. These results serve as a validation dataset for numerical simulations. An open source CFD code library (OpenFOAM) is used for numerical computations. These unsteady RANS computations were performed at the same load condition corresponding to experimental data. Parallel numerical simulations were carried out on 128 processor cores. In order to resolve turbulence Menter's k-? SST model was utilized, flame behavior on the other hand was described by Weller's b-? flamelet model. A block structured all hexahedral mesh was used.<B>Findings</B> - It is observed that two counter rotating vortices in the main recirculation zone is responsible from flame stabilization. Weak secondary recirculation zones are also present at the sides above the dump plane. Flame front location was inferred from Mie scattering images. Experimental findings show that the flame anchors both on the tip of the center body and also at the rim of the outlet pipe. Numerical simulations capture the complex interactions between the flame and the turbulent flow. These results qualitatively agree with the flame structure observed experimentally.<B>Practical implications</B> - Swirl stabilized combustion systems are used in many practical applications ranging from aeroengines to land based power generation systems. There are implications regarding the understanding of these combustion systems. <B>Originality/value</B> - The paper provides experimental insight into the application of a combustion model for a flame configuration of practical interest. Article literatinetwork@emeraldinsight.com (Onur Tuncer, Bertan Kaynaroglu) Tue, 29 Apr 2014 00:00:00 +0100 Propeller disk presented by distribution of velocities http://www.emeraldinsight.com/journals.htm?issn=0002-2667&volume=86&issue=3&articleid=17108081&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - The purpose of this simulation is to describe turbulent fluid flow through a symmetrical tube with a propeller disk set inside it.<B>Design/methodology/approach</B> - The Navier-Stokes equations with the model of turbulence (k,omega) are used to describe this problem in space and time. The propeller disk is represented by the distribution of the vector of velocities along its radius. The main purpose is to describe boundary conditions at the inlet, at the outlet, and special compatible conditions for the simulation of the propeller disk on the both its sides. A one-side modification of the Riemann problem is used for the boundary value conditions. Total pressure and total density values, and the angle of attack equal to zero are to be used preferentially at the inlet whereas pressure should be used at the outlet. At the back side of the propeller disk, it is advantageous to use total density and total pressure distribution coming from the distribution of axial velocities on the disk and the total state values at the inlet, and extra added velocities of rotation. At the front side of the propeller disk, it is preferable to use the distribution of flowing mass known from the state values computed on the disk.<B>Findings</B> - This set of boundary conditions allows to simulate air flow twisting behind the propeller / fan including corresponding pressure increase. The advantage of this approach is possibility to solve axial cuts of air ducts.<B>Practical implications</B> - The advantage of this approach is possibility to solve axial cuts of air ducts. Similarly, it is possible to solve air flow around the engine nacelle of propeller aircraft. By this approach it is possible to separate the design of axial cut air duct from the propeller solution.<B>Originality/value</B> - This approach has been used for new air duct designed on the operating conditions with Star-CCM+ solver. Article literatinetwork@emeraldinsight.com (Nikola Žižkovský, Jaroslav Pelant, Martin Kyncl) Tue, 29 Apr 2014 00:00:00 +0100 Formulation of the optimization problem for engine mount design – tractor propeller case http://www.emeraldinsight.com/journals.htm?issn=0002-2667&volume=86&issue=3&articleid=17108129&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - The engine mount design optimization problem requires a selection of the most important parameters, which influence on the final solution. The presented work is focused on creation of the mathematical model for optimization problem and methodology for selection the most important parameters<B>Design/methodology/approach</B> - Two tiers optimization algorithm was considered. First geometry of engine mount is optimized taking into account the sum of load, next the weight is minimized<B>Findings</B> - Several parameters were selected as the essential set of factors for the engine mount design and for optimization in order to get the minimal weight for the system of engine and engine mounting design<B>Research limitations/implications</B> - As a case study the single turboprop engine attached to the front part of fuselage - the so-called tractor propeller configuration - was considered<B>Practical implications</B> - The paper contains the proposal of methodology, which is going to be used in ESPOSA project to optimize the new designed engine mount<B>Originality/value</B> - This paper presents the new developed methodology, that could be useful within engine mount design Article literatinetwork@emeraldinsight.com (Tomasz Goetzendorf-Grabowski) Tue, 29 Apr 2014 00:00:00 +0100 Multiple objective optimization of the power unit for a very light jet http://www.emeraldinsight.com/journals.htm?issn=0002-2667&volume=86&issue=3&articleid=17108083&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - The purpose of this paper is to propose a solution of the engine bypass ratio choice problem of a Very Light Jet (VLJ) class aircraft using the multiple objective optimization method.<B>Design/methodology/approach</B> - The work focuses on the choice of one of the most essentials parameters of the jet engine, that is its bypass ratio. The work presents the methodology of the optimal designing using the multi-task character of the matter which is based on the mathematic model of optimization in the concept of the set theory. In order to make an optimal choice of the chosen parameter a complete computational model of an aircraft was made (aerodynamic, power unit, performance and cost) and then the method allowing to choose the bypass ratio was selected regarding multiple estimating criteria of the obtained solutions. The presented method can be used at the concept design state for determining the chosen and most important technical parameters of the aircraft.<B>Findings</B> - The way to design a competing aircraft is to choose its design parameters, including the power unit, by using the advanced methods of multiple objective optimization. The main aim of the work was to demonstrate a method of selection chosen parameters of the transport aircraft at the preliminary design stage. The work focuses on the choice of bypass ratio of the jet engine of the Very Light Jet. The method could be helpful at preliminary design stage of a new aircraft to selection another design parameters.<B>Research limitations/implications</B> - The exemplary calculations were made for 50 different transport tasks in order to take into account different performance conditions of the aircraft. The presented method can be used at the concept design state for determining the chosen and most important technical parameters of the aircraft.<B>Practical implications</B> - The work shows a practical possibility to implement the proposed method. The presented method could be helpful at preliminary design stage of a new aircraft to selection its design parameters. The results of the analyses are a separate point for further research and studies.<B>Originality/value</B> - The work shows a practical possibility to implement the proposed approach for design problems at early stages of a product development. Article literatinetwork@emeraldinsight.com (Andrzej Robert Majka) Tue, 29 Apr 2014 00:00:00 +0100 Simplified thermo-fluid model of an engine cowling in a small airplane http://www.emeraldinsight.com/journals.htm?issn=0002-2667&volume=86&issue=3&articleid=17108118&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - An aircraft engine system is composed of different elements operating at various temperatures and in conjunction with the composite nacelle creates a region with high intensity of heat transfer to be covered by the cooling/ventilation systems. Therefore a thermal analysis, accounting for the complex heat transfer modes, is necessary in order to verify that an adequate cooling is ensured and that temperatures of the nacelle are maintained within the operating limits throughout the whole aircraft’s flight.<B>Design/methodology/approach</B> - Simplified numerical simulations of conductive, convective and radiative heat transfer in the engine bay of the small airplane I-23 in a tractor arrangement were performed for different air inlets and outlets configurations and for varying conditions existing at air inlets during the flight. The model is based on the control volume approach for heat and fluid flow as well as for thermal radiation and on k-epsilon turbulence model.<B>Findings</B> - The flow and temperature distributions inside the cowling were determined and high-temperature spots on the internal side of the nacelle and on other airplane systems located close the turboprop engine and the exhaust system were found. The thermal radiation was found to play the key role in heat transfer inside the engine bay. Optimal configuration of air inlets and outlets was determined.<B>Practical implications</B> - The obtained results will help in future studies on ventilation and cooling systems and will contribute to selection of materials for parts of the engine bay and the nacelle as well as in developing solutions for reducing temperature inside the cowling of the airplane I-23.<B>Originality/value</B> - A complete simplified thermo-fluid model of heat transfer inside the engine bay of the airplane I-23 was developed. Additionally influence of the thermal radiation on temperature distribution at the nacelle was investigated. Article literatinetwork@emeraldinsight.com (Piotr Lapka, Miroslaw Seredynski, Piotr Furmanski, Adam Dziubinski, Jerzy Banaszek) Tue, 29 Apr 2014 00:00:00 +0100 The preliminary design of the air-intake system and the nacelle in the small aircraft-engine integration process http://www.emeraldinsight.com/journals.htm?issn=0002-2667&volume=86&issue=3&articleid=17108124&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - The results of preliminary design and optimisation of the air-intake system and the engine nacelle have been presented. The work was conducted as part of an integration process of turboprop engine in a small aircraft in tractor configuration.<B>Design/methodology/approach</B> - The preliminary design process was performed using a parametric, interactive design approach. The parametric model of the aircraft was developed using the PARADES™ in-house software. The model assumed a high level of freedom concerning shaping all the components of aircraft important from the point of view of the engine integration. Additionally, the software was used to control the fulfilment of design constraints and to analyse selected geometrical properties. Based on the developed parametric model, the preliminary design was conducted using the Interactive Design and Optimisation methodology. Several concepts of the engine integration were investigated in the process. All components of the aircraft propulsion system were designed simultaneously to ensure their compliance with each other. <B>Findings</B> - The concepts of the engine integration were modified according to changes in the design and technological constraints in the preliminary design process. For the most promising configurations, CFD computations were conducted using commercial RANS solver FLUENT™ (ANSYS). The simulations tested the flow around the nacelle and inside the air-delivery system which consists of the air-intake duct, the foreign-particles separator and the auxiliary ducts delivering air to the cooling and air-conditioning systems. The effect of the working propeller was modelled using the Virtual Blade Model implemented in the FLUENT code. The flow inside the air-intake system was analysed from the point of view of: minimisation of pressure losses in the air-intake duct, the quality of air stream delivered to the engine compressor, and the effectiveness of the foreign-particles separator.<B>Practical implications</B> - Based on results of the CFD analyses, the final concept of the turboprop engine integration has been chosen.<B>Originality/value</B> - The presented results of preliminary design process are valuable to achieve the final goal in ongoing project. Article literatinetwork@emeraldinsight.com (Jerzy ZÓLTAK, Wienczyslaw STALEWSKI) Tue, 29 Apr 2014 00:00:00 +0100