KEDIMA
Avioanele comerciale și sectorul aviatic în general se confruntă în zbor cu apariția turbulențelor, ceea ce impune modificări ale traiectoriei pentru a evita pe cât posibil pericolul, atât pentru aeronave cât și pentru pasageri.
Rezultate – Etapa I
Etapa 1 „Dezvoltarea bazei teoretice si a logisticii pentru demonstrarea metodei” cuprinde urmatoarele activitati:
Act 1.1 – Evaluarea metodelor de analiza si identificare a intensitatii turbulentei pentru diagnoza si prognoza de aviatie. State of the art;
Act 1.2 – Studiu teoretic al parametrilor de masurat in WT pentru evaluarea caracteristicilor de turbulenta (EDR, numar Richardson).
Act 1.3 – Elaborarea unui program general de incercari in WT pentru masurarea si calcularea EDR si Ri.
Act 1.4 – Achizitionare echipamente.
Act 1.5 – Diseminarea rezultatelor. Publicare lucrari, participare la conferinte nationale sau internationale.
Aceste activitati au fost realizate si, implicit, Obiectivele O1 si O7 aferente: O1. Tur de orizont al metodelor de diagnoza si prognoza a turbulentei utilizate in aviatie; O7. Diseminarea rezultatelor.
Turbulenta este un proces in cascada, prin care energia cinetica este transferata de la vartejuri mari la vartejuri mici, unde se disipa in caldura, iar rata transferului de la mare la mic este aceeasi cu rata de disipare in caldura in vartejurile cele mai mici.
(u ·∇)u, responsabil de generarea turbulentei, i.e., variatii continue si dezordonate ale marimilor fizice (viteza, pozitie, energie).Transferul de caldura si tensiunea de frecare in interiorul curgerii nu se pot masura direct, ci doar indirect, prin intermediul masurarii fluctuatiilor de viteza si de temperatura, si prin intermediul corelatiilor acestora.
Tabel 1: corespondențadintrenivelurile de intensitate (severitate) a fenomenului de turbulență și valorile parametrului EDR [m2/3/s], pentru aeronave de transport, de clasă medie* care se deplasează în condiții de zbor tipice (altitudine, viteza, greutate).
| ZERO | UȘOARĂ | MODERATĂ | SEVERĂ | MOG** | |
| conf. [18] | ≤ 0.15 | > 0.15 & ≤ 0.22 | > 0.22 & ≤ 0.34 | > 0.34 | > 0.22 |
| conf. ICAO 2001 [19] | ≤ 0.10 | > 0.10 & ≤ 0.30 | > 0.30 & ≤ 0.50 | > 0.50 | > 0.30 |
| conf. ICAO 2007 [17] | ≤ 0.10 | > 0.10 & ≤ 0.40 | > 0.40 & ≤ 0.70 | > 0.70 | > 0.40 |
| conf. ICAO2020 [20] | ≤ 0.10 | > 0.10 & ≤ 0.20 | > 0.20 & ≤ 0.45 | > 0.45 | > 0.20 |
| conf. [21] | ≤ 0.10 | > 0.10 & ≤ 0.30 | > 0.30 & ≤ 0.50 | > 0.50 | > 0.30 |
| conf. [22] | ≤ 0.14 | > 0.14 & ≤ 0.34 | > 0.34 & ≤ 0.54 | > 0.54 | > 0.34 |
| conf. [23] | ≤ 0.03 | > 0.03 & ≤ 0.07 | > 0.07 & ≤ 0.16 | > 0.16 | > 0.07 |
| conf. [24] | ≤ 0.14 | > 0.14 & ≤ 0.23 | > 0.23 & ≤ 0.46 | > 0.46 | > 0.23 |
| conf. [25] | ≤ 0.14 | > 0.14 & ≤ 0.20 | > 0.20 & ≤ 0.41 | > 0.41 | > 0.20 |
**MOG = „moderate or greater”, turbulențe de intensitate moderată sau mai mare
Diseminarea rezultatelor
1. New strategy for the safety and comfort of the passengers and aircraft crew during atmospheric turbulence – D. Enciu, I. Ursu, G. Tecuceanu, 7th European Conference on Structural Control (EACS 2022), 10-13 July 2022, Warsaw, Poland
Abstract
An airplane trip can be psychological terrifying for any traveler. If, during the flight, the airplane meets a turbulent air front, then the scenario is perfect for a Hollywood movie, and the panic among passengers increases proportionally with the severity of the turbulence. In this paper, a new approach of the turbulence mitigation methodology is proposed based on a solid background using an active control vibration. The experimental model is represented by a realistic, elastic airplane wing model controlled by an electric linear servoactuator. The mathematical model is completed by numerical simulations and experiments in the subsonic wind tunnel upgraded with a turbulence generator. The qualification of an emergent technology of this type will have double impact: for the passengers – safety and mental comfort increasing given by the significant reduction of the dynamic effects produced by the turbulent field; for the airplane – weight optimization based on the loads control generated by the atmospheric turbulence.
2. On the evaluation of turbulence parameters in the Wind Tunnel – D. Enciu, I. Ursu, G. Tecuceanu, International Conference of Aerospace Sciences „AEROSPATIAL 2022”, 13-14 October 2022, INCAS, Bucharest, Romania
Abstract
Commercial aircraft and aviation, in general, face in flight the appearance of turbulent fields, which requires immediate changes in airplane trajectory in order to avoid as much as possible the danger to aircraft and passengers. Up until 2010, the International Civil Aviation Organization (ICAO) [1] considered AIREPs (an automated report of weather conditions encountered during flight) and PIREPs (pilot report about weather conditions encountered during flight) a turbulence intensity indicators. In order to avoid the subjectivity of those reports, which were dependent on the type of aircraft, air speed, pilot experience, the reaction of the crew and the movement of unsecured objects around the cabin, an in situ turbulence reporting algorithm based on ICAO standard EDR index (eddy dissipation rate) has been considered [2]. The EDR index is defined as the cubic root of the turbulence energy per unit time and mass [3]. In turbulent motion there is a cascading process, through which kinetic energy is transferred from the larger eddies to the lowest eddies, where it dissipates in heat, and the energy transfer rate from the larger eddies to a smaller ones is the same as the rate of energy dissipation in heat in the smallest eddies. This is how the process of dissipation and decay of fractal-generated turbulence takes place. The theoretical background is based on the Kolmogorov approach [4], [5]. The determination of the order of magnitude of the energy dissipation during the turbulent motion has as reference the procedure described in [6]. The intensity of turbulence will be identified in the INCAS subsonic wind tunnel (WT). The turbulence is produced by a passive turbulence generator [7]. A Big Data volume is in this way obtained and becomes the basis of statistical calculations for turbulence diagnosis and forecasting.
3. Towards improving passangers safety and comfort based on turbulence test in aerodynamic tunnel – D. Enciu, I. Ursu, The 8th Conference of the Sustainable Solutions for Energy and Environment (EENVIRO 2022), 16-20 October, UTCB, Bucharest, Romania
Abstract
First, the article outlines the elements of an ongoing research project, aiming to demonstrate that the basic ICAO standard EDR (Eddy Dissipation Rate) index of atmospheric turbulence intensity, defined as the cubic root of the turbulence energy per unit time and mass, can be measured and calculated in Wind Tunnel (WT) according to the basic Kolmogorov concept. This involves showing that EDR index calculated in WT, taking a sufficient number of velocity measuring points, can be an objective measure of turbulence intensity, independent of the body immersed in the fluid. Secondly, it is shown that these measurements are accompanied by intermediate active vibration control tests. For this purpose, a Turbulence Generator was built and installed in the WT and an intelligent wing model with implemented LQG active control was introduced in the WT. These two procedures, complementary in substance, aim to demonstrate the consistency of the flight approach based on the objectivity of this ICAO standard EDR index and the vibration reduction methodology in a turbulent atmospheric environment.
Rezultate – Etapa II
Etapa 2 a proiectului se numeste „Testarea, evaluarea si demonstrarea preliminara a metodologiei” si are in componenta urmatoarele activitati:
Act. 2.1 – Instalarea, calibrarea, si testarea echipamentelor hardware existente si achizitionate
Act. 2.2 – Dezvoltare software pentru achizitionare date si analiza
Act. 2.3 – O prima campanie de achizitie Big Data pentru mai multe viteze ale aerului la intrarea in WT, in absenta si in prezenta modelului de aripa
Act. 2.4 – Colectie de date si analiza, calculare EDR si Ri
Act. 2.5 – Comparatie intre datele EDR si Ri colectate in WT si cele din standardele de aviatie corespunzatoare unor tipuri de aeronave
Act. 2.6 – Diseminarea rezultatelor. Publicare lucrari, participare la conferinte nationale sau internationale.
Campania de măsurători desfășurată în prima etapă a proiectului a vizat stabilirea performanțelor necesare ale generatorului pasiv de turbulență și stabilirea parametrilor funcționali ai instalației de termoanemometrie, precum și reglajele inițiale ale tunelului aerodinamic pentru a găsi regiunea de curgere cu regimul turbulent disipativ, conform teoriei curgerii în spatele unui grilaj, și modul optim de explorare a regiunii de interes. Pentru aceasta a fost realizat un grilaj cu ochiuri pătrate, fixat perpendicular pe direcția curgerii în camera experimentala a tunelului subsonic.
Pentru măsurarea simultana a doua componente ale vitezei curgerii in sufleria subsonica s-a folosit sistemul de termoanemometrie de precizie DANTEC StreamLine Pro, cu doua canale independente si o sonda x cu fir cald de tip 55R51. Aceasta are doua filamente orientate la 90 de grade unul față de celălalt și la 45 de grade față de curgere.
Pentru explorarea curgerii s-a folosit un sistem de traversare care efectuează o scanare în adâncime în sensul curgerii (aval) de un generator de turbulență montat în camera experimentală. Generatorul pasiv de turbulenta a generat o turbulență cvasi-omogenă în camera experimentală și a permis verificarea ipotezelor de lucru. Măsurătorile efectuate au demonstrat apariția unei turbulențe controlate, suficient de intense, la viteze de lucru de 15, 20 și 30 m/s.
Pentru procesarea datelor s-a scris si utilizat o funcție MATLAB care primește ca date de intrare două componente ale vitezei, axială și laterală, și calculează valorile pentru vâscozitatea cinematică a aerului la diferite temperaturi pe baza unei curbe interpolate din valori standard tabelate, precum și energia cinetică turbulentă a curgerii, ε, numărul Reynolds raportat la dimensiunea ochiurilor grilajului, și indicele de turbulență a curgerii.
In concluzie, campaniile de teste din suflerie s-au materializat intr-o cantitate prodigioasa de date (big data), care, prin prelucrare in cursul Etapei urmatoare, vor permite definirea si probarea teoriei lui Kolmogorov a turbulentei si vor marca un pas semnificativ spre intelegerea metricii EDR ca parametru independent de influenta fluid-structura.
Diseminarea rezultatelor
1. Articol WoS
A. Toader, I. Ursu, D. Enciu, G. Tecuceanu, Towards nonconservative conditions for equilibrium stability. Applications to switching systems with control delay, Communications in Nonlinear Science and Numerical Simulation, 121 (2023) 107188
2. WoS Proceedings
D. Enciu, I. Ursu, Towards improving passengers safety and comfort based on turbulence tests in aerodynamic tunnel, IOP Conference Series: Earth and Environmental Science, 1185 012007
3. BDI Proceedings
I. Ursu, A. Toader, G. Tecuceanu, D.Enciu, Input-to-state stability of a time-invariant system with control delay and additive disturbances, Proceedings in Applied Mathematics and Mechanics 2023;e202300152.
4. Input-to-state stability of a time-invariant system with control delay and additive disturbances – I. Ursu, A. Toader, G. Tecuceanu, D. Enciu, 93rd Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM 2023), 30 May – 2 June 2023, Dresden, Germany
Abstract
We consider a class of linear time invariant systems with control delay and additive disturbances. A state predictive feedback method is first applied to compensate the actuator delay. In this way, a closed loop system free of delay is achieved. It allows to ensure input-to-state-stability of the closed loop system. Applications are given for the lateral-directional stability of an airplane with two controls, on the aileron and on the rudder, in correlation with compliance with some regulatory flight conditions.
5. On the stability of a time-invariant linear system with time-delay and disturbances with application to aerospace engineering – D. Enciu, I. Ursu, A. Toader, 30th Annual Conference on Applied and Industrial Mathematics (CAIM 2023), 14 – 18 September 2023, Iasi, Romania
Abstract
The beauty of the mathematical equations is highlighted by presenting a practical, real application in controlling the flight stability of an airplane in a turbulent atmospheric field. This paper presents a linear mathematical model with actuator delay in the control chain and external disturbances. The time-delay is compensated by applying a state predictive feedback method and the perturbation is treated according to the basic Kolmogorov concept.
6. A Model for Turbulent Flow Energy Dissipation – practical aspects of turbulent flow investigations – C. Stoica, I. Ursu, D. Enciu, A. –M. Panait, the 40th “Caius Iacob” Conference on Fluid Mechanics and its Technical Applications, 19 – 20 October 2023, Bucharest, Romania
Abstract
Abstract. This paper describes the authors recent practical explorations of turbulent flow physics, aiming to model the energy dissipation in accordance with the Kolmogorov theory. A simple experiment consisting in a static turbulence generating grid installed in the Subsonic Wind Tunnel at INCAS and a hot wire two filament probe coupled with a thermal probe mounted on a computer-controlled positioning system was used to scan the resulting turbulent flow. The chosen station points behind the grid, at two different heights (distances from the tunnel floor) and three airspeeds were set up so that the flow is explored in all its interesting regions- the chaotic turbulent, the dissipative quasi-ergodic and the outside flow, not masked by the turbulence generating grid. The final purpose of the work was to find the region where the ergodic assumption applies and for that region to compute the EDR – Eddy Dissipation Rate – as a measure of the behavior of uniformly turbulent flow. Turbulent flow modelling is important in order to mitigate the problems it poses to general aviation when occurring in free flight. Turbulence, especially of the so-called “clear air “type, is almost impossible to detect and generates extraneous structural loading on airframes, reducing their working life and MTBF – Mean Time Between Failures. Understanding, predicting and accurately measuring the phenomenon and its effects is therefore of the greatest importance to general aviation. The work is drafted in support of the activities in the KEDIMA project and describes part of the practical exploration phase, namely the data gathering procedure. Data collected in this measurement campaign will be used to test the fit to a Kolmogorov turbulent flow model and to calculate a most important parameter, the Eddie Dissipation Rate.
7. The stability of a linear time-invariant system with control delay. Application to the stability of the aircraft control chain in conditions of atmospheric turbulence – A. Toader, D. Enciu, I. Ursu, 20th International Conference on Informatics in Control, Automation and Robotics (ICINCO 2023), 12-16 November 2023, Rome, Italy
Abstract
A class of time-invariant linear systems with control delay and additive disturbances is considered. Through a predictive state feedback method, the control delay is compensated, reaching a closed-loop system without delay. Based on a theorem of F. Mazenc, S.-I. Niculescu, M. Krstic, stability is ensured in the presence of disturbances. The application is made on the control chain of an airplane, in the presence of Dryden-type atmospheric turbulence.
8. An innovative method to evaluate the Eddy Dissipation Rate (EDR) in a subsonic wind tunnel – preliminary results of KEDIMA project – A. A. Radu, A. –M. Panait, I. Ursu, invited lecture, Ovidius University of Constanța, 07 November 2023
Abstract
Turbulence means random, unpredictable – chaotic fluid flow. This fluid motion is characterized by nonlinearity, vorticity, diffusivity, and energy dissipation. When it shows up in the atmosphere, turbulence becomes an aviation hazard. Over the course of time, it has been the most dangerous and difficult to tackle hazard, being the leading weather-related cause of aircraft accidents and incidents. The Eddy Dissipation Rate (EDR) is an aircraft-independent measure of turbulence intensity and it is defined as the cube root of the dissipation rate of turbulence kinetic energy. The larger the EDR is, the stronger the turbulence is. EDR is a parameter used to determine the amount of energy lost by the viscous forces in the turbulent flow and it represents the transmission rate of the disturbance energy from the larger-scale vortex to the smaller-scale vortex. It has become the atmospheric turbulence metric required by the International Civil Aviation Organization (ICAO) for routine turbulence reporting. One of the major objectives of KEDIMA project is to determine the EDR values in a subsonic wind tunnel. The experimental set-up encompassed a propeller, a grid, a hot-wire probe and temperature sensors. The analysis performed here relied on hot-wire data taken downstream of the grid in a flow with nominal mean velocities of 15, 20, and 30 m/s. These are preliminary results for KEDIMA project.
Rezultate – Etapa III
Etapa 3 a proiectului se numeste „Masuratori finale si analiza rezultatelor” si are in componenta urmatoarele activitati:
Act. 3.1 – A doua campanie de achizitie Big Data si finalizarea testelor de determinare a indicilor de intensitate a turbulentei
Act. 3.2 – Aplicare de control activ inteligent neuro-fuzzy
Act. 3.3 – Diseminarea rezultatelor. Publicare lucrari, participare la conferinte nationale sau internationale
In cea de-a doua campanie de masuratori, in sufleria subsonică INCAS București, a fost instalată macheta unei aeronave, iar în spatele ei, au fost amplasate sonde cu fir cald. Sondele cu fir cald au măsurat curgerea turbulentă a aerului, turbulența fiind generată de întreaga suprafață a machetei. Pentru fiecare viteza masurata au fost achiziționate seturi de date care ulterior au fost prelucrate și analizate statistic.
Pe modelul unei aripi inteligente instalate in tunelul aerodinamic se ilustrează o abordare, din perspectiva inteligenţei artificiale, a unui algoritm de control, utilizând reţeaua neuronală cea mai simplă − perceptronul elementar −. S-a luat in considerare un model matematic cu doua moduri, cele de baza, de incovoiere si de torsiune
Diseminarea rezultatelor – Articole WoS
1.1 D. Enciu, A. Toader, I. Ursu (2024) Further results on the input-to-state stability of a linear disturbed system with control delay, Mathematics, vol. 12, pp. 634, https://doi.org/10.3390/math12050634, IF 2.4
1.2. I. Ursu, G. Tecuceanu, D. Enciu, A. Toader, I. Nastase, M. Arghir, M. Calcea, A smart wing model: from designing to testing in wind tunnel with turbulence generator, Aerospace, under review