Undergraduate Thesis

In my undergrad senior year, I completed a "Thesis" equivalent to six (06) credit hours titled "Transonic Aerodynamics with Airfoil Cascade".

Abstract

In modern-day’s high-performance turbomachines require to experience higher load with reduced number of stages, thus leading their operating condition in transonic flow field phenomena.   Due to  high  loading  within  airfoil  cascades,  air  velocity  transitions  from  transonic  to supersonic condition, leading the generation of shock-waves within the flowfield. These shock waves could interact with the airfoil surface boundary layer and cause unsteady boundary layer separation.  In fact, SBLIs occur when a shock wave and a boundary layer converge and since both can be found in almost every supersonic flow, these interactions are quite expected. SBLI is also the reason of flow unsteadiness.  Shock Induced Oscillations (SIO), aerodynamic instabilities, high Cycle Fatigue failure (HCF) and so on are the detrimental consequences of this unsteady shock wave boundary layer interaction.In recent years, many investigations have been conducted to familiarize with the flow behavior of the transonic condition, but considering an isolated airfoil.  Therefore, little information is known about the airfoil cascade. The goal of the present research is to analyze and to understand the transonic flow phenomena in a circular arc airfoil cascade using numerical computation. A Reynolds averaged Navier-Stokes (RANS) solver was used to provide airfoil surface pressures,overall performance from wake characteristics and so on.  Attention is to be paid on the embedded shock wave structure and an accurate simulation of the SWBLI. The numerical studies were performed for Pressure Ratios of 0.76, 0.74, 0.72 and 0.70.  Fluctuating pressure histories are recorded at different locations in the flow field.   For different pressure ratios, peak RMS of pressure oscillation (prms/q0) is calculated and its location is identified.

Mesh 

Key Findings:

•  A complete unsteady nature is found with time and pressure ratio.

• The interrupted shock wave oscillation suggests that it is of Tijdeman B type shock.

• Positions of the shock wave show a cyclic nature related to the unsteady shock oscillation.With the change of Pressure Ratio (PR) there is a variation of the positions of the shock generation.

• The flow field reveals the the variation of the type of shock generation.

• The region of shock movement increases with the decrease of PR.

• The flow field remains undisturbed from the leading edge to the certain location of x/c=0.56 in all cases.

Current Research 

Currently, I have been working with several research works, two of them have been published in the  International Conference on Mechanical, Industrial and Materials Engineering (ICMIME) 2017, organised by Rajshahi University of Engineering & Technology. My current research work includes:

• Observation of unsteady shock behavior around a biconvex circular arc airfoil with circular cavities on it in a channel 

• Numerical analysis of shock oscillation around a biconvex circular arc airfoil by incorporating a bump on it in a channel 

• Transonic aerodynamics of airfoil cascade for different Angle of Attack (AoA), what is previously done for zero degree of AoA in my thesis work.