Humrutha G

Bio: Humrutha G is an academic researcher from Indian Institute of Technology Kharagpur. The author has contributed to research in topics: Boundary layer & Supersonic speed. The author has an hindex of 2, co-authored 4 publications receiving 25 citations.

Review of Computational Fluid Dynamics Studies on Jets

Abstract: The present work reviews the CFD studies carried out in the last more than fifty years to understand the uncontrolled and controlled jet characteristics. The chronological evolution of investigations on jets are reviewed, however they are presented according to their relevance in the discussion. The study also highlights the complexities involved in adaptive turbulence models in a realistic simulation of free jets. These complexities are largely due to entrainment of jets, large perturbations present at low Reynolds numbers in subsonic jets and strong wave interactions in jets exiting at supersonic Mach numbers from convergent-divergent nozzles. The accurate capturing of these perturbations, shock-cell structures in jets poses a real challenge in the CFD analysis. The complexities of capturing shock and expansion waves accurately in supersonic jets, is the critical step in the simulation.

Near-Field Effectiveness of the Sub-Boundary Layer Vortex Generators Deployed in a Supersonic Intake

Abstract: In aircraft engines operating at high Mach numbers, it is exigent to reduce the magnitude of flow speed from supersonic to subsonic before entering the burner, to accomplish a proficient ignition. It is accomplished by a progression of oblique shocks as well as a normal shock wave in supersonic intakes. However, the advantage of shock enabled compression in intakes does not come independent but with colossal losses due to shock-boundary layer interactions, which includes intake unstart and an abrupt thickening/separation of the boundary layer. Controlling these interactions by boundary layer control using micro-vortex generators (MVGs) has gained prominence. In the present study, an attempt is made to control the interactions at the shock impact point in a Mach 2.2 mixed compression intake. Two types of MVGs; a conventional configuration and an innovative ramped-vane configuration were experimentally investigated by varying the MVG heights as 600, 400, and 200 μm. Also, the near-field effects of MVGs are quantified in terms of static pressure variation in the internal flow. It is found that the innovative MVGs of height 200 μm leads to favorable pressure drop in both the upstream and downstream region, due to enhanced flow mixing near the boundary layer.

Bridging between eddy-viscosity-type and second-order turbulence models through a two-scale turbulence theory

Abstract: A gap between eddy-viscosity-type and second-order models is bridged using the results of a two-scale direct-interaction approximation developed for the study of turbulent shear flows. This work provides a method for incorporating the findings from models of eddy-viscosity-type into second-order models, and vice versa. Specifically, the effect of helicity controlling energy-cascade processes is incorporated into a second-order model. Then, a higher-order eddy-viscosity-type expression for the Reynolds stress is derived through the application of an iterative approximation to the second-order model

Control of a Supersonic Inlet in Off-Design Conditions with Plasma Actuators and Bleed

Abstract: Supersonic inlets are a key component of present and future air-breathing propulsion systems for high-speed flight. The inlet design is challenging because of several phenomena that must be taken under control: shock waves, boundary layer separation and unsteadiness. Furthermore, the intensity of these phenomena is strongly influenced by the working conditions and so active control systems can be particularly useful in off-design conditions. In this work, a mixed compression supersonic inlet with a double wedge ramp is considered. The flow field was numerically investigated at different values of Mach number. The simulations show that large separations appear at the higher Mach numbers on both the upper and lower walls of the duct. In order to improve the performances of the inlet two different control strategies were investigated: plasma actuators and bleed. Different locations of the plasma actuator are considered in order to also apply this technology to configurations with a diverter which prevents boundary layer ingestion. The potential of the proposed solutions is investigated in terms of total pressure recovery, flow distortion and power consumption.