High-lift airfoils operating at low Reynolds numbers are governed by laminar boundary-layer behavior, in which laminar separation bubbles significantly influence lift generation and overall aerodynamic performance. In the existing literature, laminar separation bubbles are generally considered an inherent feature of low-Reynolds-number operation and are often associated with reduced...
Quantitative infrared thermography (QIRT) is employed for non‑intrusive, area‑wide temperature measurements in high‑speed aerodynamic facilities, where accurate surface‑temperature data are essential for determining local heat‑flux densities. A series of wind‑tunnel experiments at the Mach 6 flow condition of the Ludwieg-Tube facility Göttingen (RWG) regarding a 2D shock wave impinging on a...
Infrared thermography (IR) is often used in aerothermal testing of turbine components as a non-intrusive technique for accurate measurements of blade surface temperature. Subsequently, measured surface temperatures can be used to derive heat transfer coefficients, adiabatic wall temperatures, and metal and cooling effectiveness.
Recently, an IR system has been successfully deployed to...
A variety of experimental techniques has been developed to analyse the aerodynamics of immersed bodies, classified based on their measurement principles. Specifically, phenomena like transition and separation have been observed through different experimental techniques, such as oil flow visualization, the use of pressure and temperature sensitive paint, Particle Image Velocimetry and Infrared...
Thermal imaging offers a unique opportunity to study gas/vapour–liquid mass transfer processes and liquid-phase hydrodynamics. In this work, we develop quantitative infrared thermography (QIRT)-based methods for the study of flowing liquid films under absorption and distillation conditions.
Depending on the system under study, the thermographic outcomes are two-fold. For semi-transparent...
The aerodynamics and heat transfer of a vehicle is strongly impacted by the development of the boundary layer. In particular, the transition from laminar to turbulent leads to increased heat transfer and aerodynamic drag. In hypersonic regime, this phenomenon needs to be carefully evaluated to ensure vehicles reliability.
The use of computational techniques alone is not always reliable in...
Wind turbine rotor blades are continuously exposed to harsh environmental impacts such as erosion and contamination during operation. Even small-scale surface disturbances can induce premature laminar–turbulent transition of the aerodynamic boundary layer, leading to significant performance losses. Therefore, a measurement method is needed to detect emerging local disturbances on the rotor...
INTRODUCTION
Interest in unmanned aerial vehicle (UAV) technology has been rapidly growing given its applicability across a wide range of fields, including disaster risk management, agricultural monitoring, and commercial services.
UAVs tipically employ small-scale propellers operating at low Reynolds, making them susceptible to the detrimental effects of Laminar Separation Bubbles...
The efficiency of vapor compression cycles (VCC) such as those used in aeronautical Environmental Control Systems (ECS) is heavily dependent on the performance of the evaporator. A critical technical challenge related to the latter is the maldistribution of two-phase refrigerant flow within the header and channels, which can lead to thermal losses of up to 30%. With the pressing transition...
Jet impingement is a widely used forced convection technique characterized by a stagnation region and a radially developing wall jet, which can markedly thin the thermal boundary layer near the stagnation region and produce locally high heat transfer rates [1]. It is applied in systems with high heat fluxes and tight thermal constraints, including gas turbines, electronics [2], and grinding...
Infrared thermography has emerged as a key diagnostic technique for measuring heat transfer on rotating turbine components under engine-representative conditions, where conventional techniques are often limited. In the Oxford Turbine Research Facility (OTRF), UK national engine-representative high-pressure turbine test facility, an infrared thermography methodology has been developed to enable...
This study presents experimental results on non-stationary thermal and gas-dynamic processes emerging from the interaction of a plane shock wave (Mach 2.0–4.5) with axisymmetric blunt-cylinder models (sphere-blunted cylinder and a flat-nosed cylinder) in a shock tube channel.
The research employed combined high-speed optical and infrared diagnostics. Gas-dynamic structures were visualized...
Spray cooling is a high-performance thermal management technique capable of dissipating extremely high heat fluxes while enabling compact system designs. It is regarded as a key enabling technology in applications where conventional air or single-phase liquid cooling is no longer sufficient, including power electronics and high-performance computing, aerospace and defense systems, high-power...
The paper presents cooling system based on the Indirect Regenerative Evaporative Cooling concept. The developed prototype of the IREC system for electronics cooling is presented. Cooling relies on forced convection, where air is significantly cooled through evaporation. The system features two types of channels - dry and wet, through which the cooled air and moist air circulate. Water is...
InfraRed Thermography (IRT) enables real-time, non-contact thermal inspection without harming the object or producing hazardous radiation and provides two-dimensional temperature distributions to detect early signs of structural irregularities, supporting continuous structural health monitoring across various industries. While thermal imaging can reveal the presence of damages, it is extremely...
The broad applicability and effectiveness of impinging synthetic jets (SJs) in thermal management have motivated extensive efforts to refine their design through systematic examination of key parameters, including stroke length and Reynolds number [1–2]. Earlier investigations [3–4] have demonstrated that nozzle geometry plays a significant role in determining the heat transfer of impinging...
An experimental and numerical study of high-speed gas-dynamic and thermal processes is carried out, which are realized during the simultaneous interaction of the plane shock wave (SW) and its co-flow with 1) shock tube test camera walls 2) the combined pulsed (submicrosecond) volume discharge in the test camera 3) the axisymmetric sphere-blunted cylinder model after volume discharge...
Reducing skin-friction drag in turbulent flows remains a central challenge in fluid mechanics due to its direct impact on energy consumption in aerodynamic and hydrodynamic applications. Drag reduction strategies are commonly divided into active and passive techniques. Active methods require an external energy input and include flow control approaches such as fluid injection, suction, and wall...
High-lift capability remains a key requirement for aircraft during take-off and landing, traditionally achieved through passive high-lift devices such as slats and flaps that, over the years, have undergone continuous refinement, leading to increasingly efficient but also mechanically complex systems [1]. Active flow-control concepts, such as circulation control (CC), offer a lighter and...
