The effect of the damage on the aerodynamic characteristics of wing with respect to the three-dimensional effects
Soheila
Abdolahi Poor
عضو هیات علمی / پژوهشگاه هوافضا، وزارت علوم، تحقیقات و فناوری
author
Mahmoud
Mani
عضو هیات علمی / دانشکده مهندسی هوافضا، دانشگاه صنعتی امیرکبیر
author
text
article
2016
per
In this paper the flow on a finite wing with triangular damage is numerically and experimentally investigated to understand the influences of damage on the aerodynamic characteristics of wing. To study the effects of different span positions, the damage was considered in tip, middle and root position of the wing span. The aerodynamic coefficients and their increments due to damage were extracted and the results were compared to each other and also to the experimental results. Then flow visualizations were practiced to make evident the flow structure on the model and to help to understand the influences of each position of damage on the aerodynamic coefficients. There was the flow through the damage which was driven by the pressure difference between the upper and lower wing surfaces. The flow could take two forms dependent on the angle of attack. The first form was a "weak-jet" which formed an attached wake and resulted in small changes in force and moment coefficients. The second form resulted from increased incidence. This was the "strong-jet" where through flow penetrated into the free stream flow with large separated wake and reverse flow. The effect on the force and moment coefficients was significant in this case. Generally comparing to an undamaged model, increasing incidence for a damaged model resulted increase loss of lift coefficient, increased drag coefficient and more negative pitching moment coefficient.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
4
v.
2
no.
2016
7
19
http://www.astjournal.ir/article_17095_e63fba75a6f7ea49b1df774f240a686b.pdf
Evaluation of wing vortex behavior at high angles of attack by using laser visualization and numerical method
Mojtaba
Dehghan Manshadi
عضو هیات علمی / مجتمع دانشگاهی مکانیک و هوافضا، دانشگاه صنعتی مالک اشتر
author
Mehdi
Feizian
کارشناس ارشد / مجتمع دانشگاهی مکانیک و هوافضا، دانشگاه صنعتی مالک اشتر
author
Mehrdad
Bazazzadeh
عضو هیات علمی / مجتمع دانشگاهی مکانیک و هوافضا، دانشگاه صنعتی مالک اشتر
author
Mehdi
Eilbeigi
دانشجوی دکتری / مجتمع دانشگاهی مکانیک و هوافضا، دانشگاه صنعتی مالک اشتر
author
text
article
2016
per
In this study, the vertical flow on a sharp edged, 70 degrees swept back delta wing was experimentally investigated in a smoke tunnel, using laser sheet technique. Previous studies show that changing Reynolds number has little effect on the vortex structure of sharp edged delta wings, although the angle of attack has the major effect. Furthermore, Spalart Almaras model is used for numerical investigation on the delta wing. The effect of angle of attack on size and break-down location of the vortices on the wing was studied. The results show that increasing of the angle of attack increases the size of the vortices and the height of the vortex core to the wing surface as well. The bigger vortex on a delta wing leads to increasing the lift of the wing and it increases the maneuverability of the aircraft. Abrupt changes occur in the structure of the vortices at very high angles of attack which is designated as vortex break-down. The vortex break-down cause’s intense oscillation of the surface pressure of the wing and it decreases the aircraft maneuverability.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
4
v.
2
no.
2016
21
33
http://www.astjournal.ir/article_18619_cccaff212491d3a3dc4d989d5e8bd490.pdf
Robust active vibration suppression of a nonlinear flexible spacecraft
Maryam
Malekzadeh
عضو هیات علمی / دانشکدة فنی و مهندسی، دانشگاه اصفهان
author
text
article
2016
per
In this paper, attitude control and active vibration suppression of flexible spacecraft using piezoelectric patches as actuator and sensor is considered. Two inner and outer loop controllers are used (inner loop for controlling panel vibration and outer loop for controlling spacecraft attitude). Piezo patches and reaction wheel are used as inner and outer loop actuator respectively. In inner loop an optimal controller has been designed for suppression of panel vibration. In outer loop, two controller feedback linearization and composite controller (combine of feedback linearization and mu-synthesis) act on rigid hub to perform spacecraft maneuver. To evaluate the performance of the proposed controllers, an extensive number of simulations on a nonlinear model of the flexible spacecraft are performed. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, panel vibration suppression, sensitivity to measurement noise, environment disturbance and nonlinearity in large maneuvers. Simulation results confirm the ability of the active controller in tracking the attitude trajectory while damping the panel vibration. It is also verified that the perturbations, environment disturbances and measurement errors have only slight effects on the tracking and damping performances in the composite method.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
4
v.
2
no.
2016
35
44
http://www.astjournal.ir/article_18727_fcc132dc06ace0fa5c6deb1c6149d380.pdf
Modeling of a lateral comb capacitive micro accelerometer system behavior for 1g acceleration
Manigheh
Zakeri
عضو هیات علمی / دانشکدة مهندسی فناوریهای نوین، دانشگاه تبریز
author
Majid
Siami
کارشناس ارشد مهندسی مکاترونیک / دانشکدة مهندسی فناوریهای نوین، دانشگاه تبریز
author
Saeed
Lamei
دانشجوی کارشناسی ارشد مهندسی مکاترونیک / دانشکدة مهندسی فناوریهای نوین، دانشگاه تبریز
author
text
article
2016
per
In this paper, behavior of a lateral comb capacitive micro accelerometer including system noise, sensitivity, and response time has been modeled and improved. Also, dynamic behavior of system has been studied based on three different functions of the input acceleration including the constant, step, and impulse functions. Hence, at first system has been investigated based on the constant input acceleration function and the simulation results has been verified with the experimental results of the existed research. Following, the improved distance between the capacitor plates has been obtained based on the minimum amount of the system total noise. Additionally, sensitivity of system has been maximized by evaluation of the proof mass amount and considering the maximum possible displacement between capacitor plates, as a constraint, to avoid connection of the electrodes. Results show that the distance between capacitor plates was reduced by 90% and the length and width of proof mass were increased by 41.5%. Eventually, sensitivity of the system was doubled. In addition, response time of the system was decreased, significantly. Also, the results of choosing different input functions for input acceleration including the impulse and step functions show that the input function is an effective factor of the model based designing. It changes both the amount of the designing parameters and prediction of the system performance.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
4
v.
2
no.
2016
45
54
http://www.astjournal.ir/article_18858_3b56e37696f2f8e722de0eb43effcc8a.pdf
An experimental investigation in effects of thermal fatigue and constant bending loading on failure of a sample of thermal barrier coatings
Mohammad
Sadeghi
کارشناس ارشد / دانشکدة مهندسی مواد و متالورژی، دانشگاه علم و صنعت ایران
author
Hoseyn
Ebrahimi
کارشناس ارشد / دانشکدة مهندسی مکانیک، دانشگاه خواجه نصیرالدین طوسی
author
Hoseyn
Arabi
عضو هیات علمی / دانشکدة مهندسی مواد و متالورژی، دانشگاه علم و صنعت ایران
author
Ali Reza
Mirhabibi
عضو هیات علمی / دانشکدة مهندسی مواد و متالورژی، دانشگاه علم و صنعت ایران
author
Soheil
Nakhodchi
عضو هیات علمی / دانشکدة مهندسی مکانیک، دانشگاه خواجه نصیرالدین طوسی
author
Hoseyn
Badrrezayi
کارشناس / شرکت مهندسی ساخت و توربین مپنا (توگا)
author
text
article
2016
per
In this study, the effects of thermal cyclic loading in the presence of a constant mechanical load were evaluated experimentally on failure of thermal barrier coatings. For this purpose, specimens of Inconel 617 with approximate dimensions of 100×10×6.2 mm that coated by two-layered thermal barrier coatings include a Ni22Cr10Al1Y bond coat and ZrO2.8wt%Y2O3 using air plasma spraying (APS), were considered. These specimens were tested under low cycle thermal fatigue experiment with maximum temperatures of 1000oC, 1100oC and 1170oC for thermal cycles and constant bending loads of 4500 Nmm, 6000 Nmm, 7500 Nmm and with no load by using a made test rig with the ability of four point bending load. In a thermal cycle, a specimen heating time was 10 minutes and cooling time was 5 minutes approximately. The results obtained in this study, showed that different loads change thermal barrier coatings failure mechanisms and service life cycles of coating reduce exponentially by rising maximum temperature of thermal cycle. Also increases in mechanical load have significant effect on the reduction of thermal barrier coatings life during thermal fatigue loading.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
4
v.
2
no.
2016
55
64
http://www.astjournal.ir/article_18916_e05ca08c6c6d4ef08edb7d0f50dcb7f1.pdf
Parametric analysis of transient performance of a turbojet engine based on nonlinear aero-thermodynamic modeling approach
Mohamad
Faraji
کارشناس ارشد / مجتمع دانشگاهی هوافضا، دانشگاه صنعتی مالک اشتر
author
Mehdi
Jahromi
عضو هیات علمی / مجتمع دانشگاهی هوافضا، دانشگاه صنعتی مالک اشتر
author
Jamasb
Pirkandi
عضو هیات علمی / مجتمع دانشگاهی هوافضا، دانشگاه صنعتی مالک اشتر
author
Mostafa
Mahmoodi
عضو هیات علمی / مجتمع دانشگاهی هوافضا، دانشگاه صنعتی مالک اشتر
author
text
article
2016
per
The present study deals with the parametric analysis of a turbojet engine performance based on transient aero-thermodynamic governing equations. The required dynamic model developed in Simulink environment. From the complex factors affecting on transient performance, three factors including rotor dynamic, volume dynamic and heat soakage is presented in the model. To validate the model results, a deceleration operation from 100% to 70% of the design rotor speed is carried out and rotational speed, thrust, turbine inlet temperature and turbine exhaust gas temperature of the present model results were compared with commercial program GSP. The results show the ability of the model to simulate the transient performance so that the maximum percentage error is less than 4 percent in thrust prediction. Then in the transient response of the engine acceleration from 70% to 100% of the rotor speed, three different rate of fuel consumption is studied. The results indicate that with sudden acceleration, temperature overshoot at the inlet to the turbine and the occurrence of compressor surge can be harmful, such that the engine acceleration during 2.5 (s) can increase turbine inlet temperature to about 21 K with respect to reference value.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
4
v.
2
no.
2016
65
76
http://www.astjournal.ir/article_18994_c06df599b771e96ec81da3346625bc61.pdf
Using statistical and artificial intelligence approach to predict the exhaust gas temperature of a micro gas turbine engine
Roozbeh
Riazi
عضو هیات علمی / دانشکدة علوم و فنون نوین، دانشگاه تهران
author
Iman
koleini
کارشناس ارشد / دانشکدة علوم و فنون نوین، دانشگاه تهران
author
Shidvash
Vakilipour
عضو هیات علمی / دانشکدة علوم و فنون نوین، دانشگاه تهران
author
Bahram
Tarvirdizadeh
عضو هیات علمی / دانشکدة علوم و فنون نوین، دانشگاه تهران
author
Hadi
Veisi
عضو هیات علمی / دانشکدة علوم و فنون نوین، دانشگاه تهران
author
Hadi
Zare
عضو هیات علمی / دانشکدة علوم و فنون نوین، دانشگاه تهران
author
text
article
2016
per
To study the relation between the amount of Exhaust Gas Temperature (EGT) as the output quantity of an experimental gas turbine engine and the parameter of engine rotational speed (RPM), as its input quantity, two different data mining approaches were employed in the present work. Artificial Neural Network (ANN) and Multiple Polynomial Regression (MPR) techniques were used to predict the nonlinear relation between the input and output of the engine. The related experiments were already performed by using an experimental micro gas turbine engine with an engine rotational speed in the range of 0 ~ 108000 RPM. The results show that, in general, both the ANN and MPR approaches have good predicting capability for estimating exhaust gas temperature values. Also the results of using the ANN and MPR approaches show that the degree of agreement between the predicted and measured values of exhaust gas temperature is higher for the case of employing the ANN approach. In other words, the ANN has better predicting capability for estimation of exhaust gas temperature than the MPR method.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
4
v.
2
no.
2016
77
94
http://www.astjournal.ir/article_19196_c1b8f71368593a93d47c739318b11829.pdf