Model-based stagnation pressure control in a supersonic wind tunnel

Upravljanje parametrima strujanja u aerotunelima je oblast intenzivnog istraživanja poslednjih godina, sa ciljem poboljšanja kvaliteta i efikasnosti rada aerotunelskih instalacija. Ovaj rad predstavlja pokušaj da se doprinese boljem razumevanju upravljanja zaustavnim pritiskom u supersoničnim instalacijama prekidnog dejstva. Razmotrena je strategija upravljanja zaustavnim pritiskom u aerotunelu T-38 Vojnotehničkog instituta u Beogradu. Poboljšani matematički model supersoničnih aerotunelskih instalacija je predložen i primenjen na aerotunel T-38. Tačnost sa kojom matematički model predviđa odziv instalacije u uslovima supersoničnog strujanja demonstrirana je poređenjem podataka iz simulacija i eksperimenata. Matematički model je upotrebljen za uvođenje izmenjenog algoritma upravljanja u polazni upravljački sistem aerotunela T-38. Aerotunelski eksperimenti su potvrdili predviđanja modela u pogledu smanjenja vremena uspostavljanja strujanja i povećanja raspoloživog vremena za merenje, čime je postignuto značajno poboljšanje efikasnosti rada aerotunela.The flow parameters control in wind tunnels is an area of intense research in recent years, with the aim of improving quality and efficiency of the wind tunnel operation. In this paper, an attempt is made to contribute to a better understanding of the stagnation pressure control in supersonic blowdown-type facilities. The stagnation pressure control strategy in the VTI Belgrade T-38 wind tunnel is discussed. An improved mathematical model for a supersonic wind tunnel is suggested and applied to the T-38 facility. Comparisons of simulation and experimental data are made to demonstrate accurate prediction of the facility response in supersonic flow conditions by the mathematical model. The model is used to incorporate a modified feedforward control in the original T-38 wind tunnel control system. The actual wind tunnel tests confirm model-predicted decrease of flow stabilization time and increase of available measurement time, bringing significant improvement in the wind tunnel operation efficiency

Model-based stagnation pressure control in a supersonic wind tunnel

Upravljanje parametrima strujanja u aerotunelima je oblast intenzivnog istraživanja poslednjih godina, sa ciljem poboljšanja kvaliteta i efikasnosti rada aerotunelskih instalacija. Ovaj rad predstavlja pokušaj da se doprinese boljem razumevanju upravljanja zaustavnim pritiskom u supersoničnim instalacijama prekidnog dejstva. Razmotrena je strategija upravljanja zaustavnim pritiskom u aerotunelu T-38 Vojnotehničkog instituta u Beogradu. Poboljšani matematički model supersoničnih aerotunelskih instalacija je predložen i primenjen na aerotunel T-38. Tačnost sa kojom matematički model predviđa odziv instalacije u uslovima supersoničnog strujanja demonstrirana je poređenjem podataka iz simulacija i eksperimenata. Matematički model je upotrebljen za uvođenje izmenjenog algoritma upravljanja u polazni upravljački sistem aerotunela T-38. Aerotunelski eksperimenti su potvrdili predviđanja modela u pogledu smanjenja vremena uspostavljanja strujanja i povećanja raspoloživog vremena za merenje, čime je postignuto značajno poboljšanje efikasnosti rada aerotunela.The flow parameters control in wind tunnels is an area of intense research in recent years, with the aim of improving quality and efficiency of the wind tunnel operation. In this paper, an attempt is made to contribute to a better understanding of the stagnation pressure control in supersonic blowdown-type facilities. The stagnation pressure control strategy in the VTI Belgrade T-38 wind tunnel is discussed. An improved mathematical model for a supersonic wind tunnel is suggested and applied to the T-38 facility. Comparisons of simulation and experimental data are made to demonstrate accurate prediction of the facility response in supersonic flow conditions by the mathematical model. The model is used to incorporate a modified feedforward control in the original T-38 wind tunnel control system. The actual wind tunnel tests confirm model-predicted decrease of flow stabilization time and increase of available measurement time, bringing significant improvement in the wind tunnel operation efficiency

Stagnation pressure transient control in a supersonic blowdown wind tunnel test facility

Research in the area of wind tunnel flow parameters control has been intensified in recent years, in an attempt to improve quality and efficiency of the wind tunnel operation. In this paper, stagnation pressure transient control in a supersonic blowdown-type wind tunnel is considered, with the aim of increasing available measurement time and bringing improvement in the operation efficiency. The stagnation pressure control strategy in the VTI Belgrade T-38 wind tunnel is analyzed. A mathematical model of a blowdown wind tunnel is developed and applied to the T-38 test facility. The model is used to incorporate a modified stagnation pressure transient control in the original T-38 control system, in order to establish the required stagnation pressure with the shortest possible settling time. The actual wind tunnel tests confirm model-predicted decrease of the pressure settling time and increase of available measurement time, bringing significant improvement in the facility operation efficiency

Laser beam effects on Cu and Ti in vacuum and in the air

Ti and Cu samples were exposed in ambient atmosphere and vacuum (0.66 mPa) to single pulse (0.2-2.6 J) ruby laser radiation in the Q-switch (30 ns) and free generation regimes (150 mu s). Acoustic recordings during irradiation were carried out and the resulting damage was analyzed by light and scanning electron microscopy. In contrast to vacuum conditions, it is observed in the air that the damaged area was much larger due to plasma effects and also that cracking of the Ti samples and oxidation of the Cu samples occurred

Damage characteristics of laser-material interaction in AlLiCuMg alloys

The hardening of two-component alloys of AlLi type is achieved by thermal precipitation, and of much practical importance are the three-component alloy group AlMgLi and multi-component AlLiCuSiMg. They possess lower values for specific weight and higher values for Young’s modulus compared to conventional aluminum alloys. Therefore, owing to their widely extended application in aircraft industry, an attempt for investigating and improving their characteristics is reasonable. In this paper an AlLiCuSiMg alloy was exposed to ruby-laser radiation, λ = 0.694 μm, 2x10exp(–6) s and 3x10exp(–8) s pulsing, and energy variations from 0.14 to 2.6 J. Scanning electron microscopy analysis of the structure has shown defined damages in the tested material. Shallow and deep craters have been observed and crater diameters have been determined. The main purpose of this investigation is to determine the differences of micro-damages in the material as a function of thermomechanical treatment. The influence of time dependent power densities (energies) was also studied.Navedeni su: Editors [https://www.gruppofrattura.it/ocs/index.php/ICF/ICF8/paper/viewFile/3892/4498