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International Review of Aerospace Engineering - October 2010 (Vol. 3 N. 5) - Papers

Sustainable Air Traffic Management System Development Methodology
A Parametric Investigation of flow through an Annular Curved Diffuser
Integral Backstepping Controller for an Autonomous Helicopter
Incorporating Industry-Recognized Safety Practices into a University-Level Technology Curriculum
Dynamic Pressure for Gas Turbine Engine Condition Monitoring
Multiquadric Approximation for Geodetic Location by Airborne Camera
Autonomous Flight Trajectory Control on Loiters with Actuator Saturation
Delay of Stall in a Radial Diffuser Using Throttle Rings

International Review of Aerospace Engineering - Papers

Sustainable Air Traffic Management System Development Methodology
by Arnaldo Valdés R., Gómez Comendador V., Pérez Sanz L.

Vol. 3. n. 5, pp. 238-248

Abstract - The objective of this paper is to present a methodology to evaluate the status of the Air Traffic Management (ATM) system in terms of the relationship between the offered capacity and the traffic demand, identifying weakness areas and proposing solutions. The first part of the methodology relates to the characterization and evaluation of the current system, while the second part analyzes the system development limit. The following general criteria are established to define the methodological framework: use of Air Traffic Control (ATC) sectors as analysis unit, consideration of network effects, tactical focus, relative character of the analysis, objectivity and a high level assessment for assumptions on the human and Communications, Navigation and Surveillance (CNS) elements. The steps followed start with definition of indicators and metrics, like the nominal criticality or the nominal efficiency of a sector; scenario characterization; network effects analysis to study the relations among the constitutive elements of the ATC system; diagnostic by means of a “System Status Diagram”; analytical study of the ATC system development limit; and finally, formulation of conclusions and proposal for improvement. This methodology was employed by the Spanish Air Navigation Service Provider in the frame of the Spanish Airspace Capacity Sustainability Program, although it could be applied elsewhere.

Keywords: Air Traffic Management (ATM), Capacity and demand balance, Airspace capacity, airspace efficiency.

A Parametric Investigation of flow through an Annular Curved Diffuser
by P. K. Sinha, A. N. Mullick, B. Halder, B. Majumdar

Vol. 3. n. 5, pp. 249-256

Abstract - In the present investigation the distribution of mean velocity, static pressure and total pressure are experimentally studied on an annular curved diffuser of 30° angle of turn with an area ratio of 1.25 at Reynolds number 2 x 105 based on inlet diameter and mass average inlet velocity. The velocity distribution shows high velocity fluids shifted and accumulated at the concave wall of the exit section due to the combined effect of velocity diffusion and centrifugal action. It also indicates the possible development of secondary motions between the concave and convex walls of the test diffuser. The experimental results then were numerically validated with the help of Fluent, which shows a good agreement between the experimental and predicted results. Based on the validated result a series of parametric investigations are conducted with same centre line length and inlet diameter but with different area ratios varying from 1.15 to 3.5. From the parametric investigation it is observed that static pressure recovery increases up to an area ratio of 2.86 and beyond this the pressure recovery decreases steadily. The coefficient of total pressure loss almost remains constant with the change in area ratio for similar inlet conditions.

Keywords: Annular curved diffuser, k-ε model, Fluent solver.

Integral Backstepping Controller for an Autonomous Helicopter
by K. Zemalache Meguenni, M. Tahar, M. R. Benhadria, Y. Bestaoui

Vol. 3. n. 5, pp. 257-267

Abstract - In this paper, we present the result of nonlinear control technique applied to an autonomous quad-rotor helicopter called X4-flyer. By using Backstepping procedure, we can stabilize the engine in hovering and generate its trajectory. Moreover, for rejecting external load disturbance, two controls are presented, PI-Backstepping which is the combination between PI and Backstepping into the so-called Integral Backstepping, and the second is Backstepping with an estimator. We studied the robustness of the used controllers in the presence of disturbances. We presented the case of the disturbances with wind influence. This allows to prove the effectiveness of the proposed control law.

Keywords: Autonomous quadrotor Helicopter, Backstepping Controller, planning algorithm.

Incorporating Industry-Recognized Safety Practices into a University-Level Technology Curriculum
by Sergey Dubikovsky, Thomas A. Goodrich, Ronald Sterkenburg

Vol. 3. n. 5, pp. 268-273

Abstract - In today’s competitive markets, it’s not enough for universities to provide students with an understanding of the theoretical aspects of engineering and technology; it’s important for students to enter the workforce with practical engineering and technology experience and skills. In order to fully educate and equip students, it has become important for universities to revise curricula to include courses that teach and develop planning, design, teamwork, communication, and manufacturing skills. Similarly, if students are to be able to transition smoothly to the workplace, they need to learn and internalize the safety practices that not only protect production workers and end-users from harm, but also protect a company’s bottom line against costly accidents and production delays. This paper examines a collegiate aviation course designed to achieve these objectives.

Keywords: Interdisciplinary, senior design projects, hands-on education, undergraduate research.

Dynamic Pressure for Gas Turbine Engine Condition Monitoring
by G. Rinaldi, I. Stiharu, M. Packirisamy, V. Nerguizian, R. Jr. Landry

Vol. 3. n. 5, pp. 274-283

Abstract - The use of dynamic pressure measurement as a diagnostic tool for gas turbine engine condition monitoring is presented. Dynamic pressure representations are shown for engine RPM, blade condition and blade-tip-clearance. The dynamic pressure is depicted as a time dependent periodic signal generated by the passing of blades beneath the sensor. The representative results show good potential for implementing the dynamic pressure approach for gas turbine engine condition monitoring. A micro-electro-mechanical-systems microphone is proposed, due to its excellent sensitivity, as the principal component of the sensor for measuring dynamic pressure in gas turbine engines. Bench-top experiments are conducted using an axial fan for measuring RPM, blade condition and surge. Field-tests to measure the engine RPM of a General Electric J-85 engine are described. Bench-top and field-test results demonstrate that dynamic pressure based diagnostics are well suited for in situ condition monitoring of gas turbine engines.

Keywords: Gas turbine engine, Condition monitoring, Dynamic pressure, MEMS.

Multiquadric Approximation for Geodetic Location by Airborne Camera
by André Silva, José Novais, K. Bousson

Vol. 3. n. 5, pp. 284-289

Abstract - The present paper addresses a method for surface reconstruction and a vision based system for position estimation and camera control, for an unmanned aerial vehicle. A theory for response surface approximation was developed to interpolate a given set of data for application in surface reconstruction and geodetic location by focus of a camera for aerial surveillance. To lock the camera in the estimated location, it is necessary to control the orientation of its focus during the flight mission using a nonlinear control method. The system can guide the camera to any point on the Earth surface or to any other point location using quaternion methods, regardless of the direction and dynamics of the disturbances that the aircraft may have.

Keywords: Multiquadrics, surface reconstruction, robust camera control, quaternions.

Autonomous Flight Trajectory Control on Loiters with Actuator Saturation
by Albano S. Q. Constante, Alessandro A. Santos, K. Bousson

Vol. 3. n. 5, pp. 290-296

Abstract - This paper deals with the problem of autonomous flight trajectory control with actuator saturation using a nonlinear feedback control method based on Lie derivatives for the navigation of unmanned aerial vehicles (UAVs). The aim of the paper is to design a trajectory control method that enables an unmanned aircraft to navigate on any of the NATO’s STANAG 4586 loiters as a continuous trajectory. The method was successfully validated on these standardized loiters for a moderate size unmanned aircraft.

Keywords: Navigation, Trajectory Guidance & Control, UAV, Nonlinear Control, Lie Derivatives, STANAG 4586, Loiters, Actuator Saturation.

Delay of Stall in a Radial Diffuser Using Throttle Rings
by Saad A. Ahmed

Vol. 3. n. 5, pp. 297-303

Abstract - Centrifugal compressors/blowers are widely used in many industrial applications. However, the operation of such compression systems is limited at low-mass flow rates by self-excited flow instabilities which could result in rotating stall or surge of the machine. These instabilities will limit the flow range in which the compressor or the blower can operate, and will also lower their performance and efficiency. Experimental techniques were used to investigate a model of radial vaneless diffuser at stall and stall-free operating conditions. The speed of the impeller was kept constant, while the mass flow rate was reduced gradually to study the steady and unsteady operating conditions of the compressor. Additional experiments were made to investigate the effects of reducing the exit flow area on the inception of stall. The results indicate that the instability in the diffuser was successfully delayed to a lower flow coefficient when throttle rings were attached to either one or both of the diffuser walls (i.e., to reduce the diffuser exit flow area). The results also showed that an increase of the blockage ratio improves the stability of the system (i.e., the critical mass flow rate could be reduced to 50 % of its value without blockage). The results indicate that the throttle rings could be an effective method to control stall in radial diffusers.

Keywords: stall, throttle rings, centrifugal compressor, radial diffuser.