بررسي عددي تاثير مكان قراردهي عملگر پلاسمايي در افزايش كارايي ايرفويل

THE NUMERICAL STUDY OF THE EFFECT OF PLASMA ACTUATOR PLACEMENT ON INCREASING AIRFOIL EFFICIENCY

تواناييِ كنترل جريان، يكي از نيازهاي اساسي در علم مكانيك سيالات است كه پيوسته توسط محققين دنبال مي‌شود. يكي از روش هاي نوين در اين حيطه استفاده از عملگرهاي پلاسمايي است كه به‌‎وسيله‌ي تزريق ممنتوم به لايه‌ي مرزي، سبب تاخير در وقوع پديده‌ي جدايش مي‌شود. هدف از اين بررسي، كنترل جريان عبوري از روي ايرفويل NLF0414 به‌كمك عملگر پلاسمايي است. براي اين منظور، ابتدا مدل‌‌سازي ايرفويل به هر دو صورت عددي و تجربي تحت شرايط كاملاً مشابه و زاويه‌ي حمله‌ي 18 درجه انجام مي گيرد. در مرحله‌ي بعد، محل قرارگيري عملگر بر روي سطح ايرفويل در ميزان به تاخير انداختن پديده‌ي جدايش به‌صورت عددي بررسي مي‌شود. نتايج نشان مي دهد كه حضور عملگر پلاسمايي درست در نوك ايرفويل بيشترين تاثير را در به تاخير انداختن پديده‌ي جدايش داشته و سبب افزايش 100% نسبت ضريب نيروي برا به ضريب نيروي پسا (بازده ايرفويل) در اين زاويه‌ي حمله‌ي مي‌شود.

The plasma actuator is one of the newest devices in flow control techniques which can delay separation by inducing external momentum to the boundary layer of the flow. The purpose of this paper is to simulate a NLF0414 airfoil, both experimentally and numerically, in the presence of the body force vector induced by a specific plasma actuator. For this reason, the simulation is done, both numerically and experimentally, for a NLF0414 airfoil with compressible 25m/s velocity airflow in two different cases: with no plasma actuator located on the airfoil and with body force produced by a plasma actuator located on the top of the airfoil, in order to investigate the effect of plasma on the flow passing over it and its effect on postponing separation flow on the airfoil. Simulation of the flow over an airfoil with the presence of a plasma actuator shows that the numerical distribution of induced body force by the actuator, which is calculated by the Suzen et al. model, is in good correlation with experimental results. The results also indicate that, by employing a plasma actuator, the airfoil characteristics improved obviously and caused more lift and less drag coefficient in the airfoil compared with cases with no plasma actuator. The results also show that the presence of a plasma actuator on the top surface of the airfoil and exactly at the tip of the airfoil transferred the separation point from x=16 mm to x=90 mm in 18 degrees of the angle of attack, which means that using the plasma actuator before the separation point on the top surface of the airfoil can delay the separation point about 74 mm. The growth of the aerodynamic efficiency of the airfoil by using a plasma actuator is so considerable, as it caused a 100% increase in the ratio of lift to drag coefficient and the efficiency of the airfoil at the same angle of attack.