The effects of Exhaust Gas Recirculation (EGR) through the dilution by carbon dioxide and water vapour on methane flames/oxygen-enriched air in the case of the pressurized premixed combustion encountered in gas turbines are studied. The chosen configuration is a confined swirled premixed flame with a constant swirl number (Sn = 0.90). The input parameters are the initial temperature, adiabatic flame

This paper presents the experimental results obtained in directly irradiated conical spouted and spout-fluid beds. A conical bed with a minimum and maximum inner diameter of 80 and 314.76 mm was filled with SiC particles and directly irradiated from the top with a beam-down reflector with a 2 kW Xe-lamp. The study examines the influence of the bed height and airflow rate on the temperature distribution

An experimental investigation on the flow topology over a rotor operating at low Reynolds numbers is presented. The feasibility of laminar to turbulent transition experiments over small rotors is demonstrated. Phase-locked infrared thermography coupled with simultaneous force and torque measurements were used to study a three bladed rotor with a NACA0012 aerofoil section set at a uniform angle of incidence

A hydraulic jump is a region of rapidly-varied flow that is extremely turbulent. While the one-dimensional continuity and momentum principles have been successfully applied to express the relationships between upstream and downstream conditions, the three-dimensional equations cannot be resolved without some complicated turbulence closure, often involving two phases, i.e. air and water. Based upon

The effectiveness of synthetic jet actuation on the wingtip vortices produced by an unswept, low aspect ratio, rectangular wing at a chord Reynolds number of 8.16×104is experimentally investigated. The synthetic jet is operated at different actuation frequencies and amplitudes in order to investigate five different control cases characterized by different momentum coefficients and dimensionless frequencies

Cavitation is likely to occur in micron clearance, which affects the efficiency and reliability of the fluid machinery. Due to the confinement effect and high-speed shearing, evolution process of cavitation bubbles takes on new characteristics in the confined clearance. In this paper, a visualized experimental apparatus was developed based on the structural characteristics of micron clearance. The

The interaction between an impacting droplet and liquid surface is complex and is strongly influenced by the liquid surface type and impact droplet factors such as its size and velocity. In this experimental study, the impacts of a single water droplet on various liquid surfaces were investigated. The diameter and velocity of the single water droplet were 2.0–3.2 mm and 0.26–3.73 m/s, respectively

In natural gas pipelines, temperature and pressure vary along the line, leading to liquid condensation in undulating sections of the pipelines. This phenomenon has a significant impact on the gas transportation efficiency and safety. In this study, an experimental investigation on liquid-carrying by a swirling flow in an undulating pipeline was carried out. As the condensate liquid would usually accumulate

Convection of a dielectric fluid confined in a differentially heated annulus with an inhomogeneous radial electric field is investigated under different gravity conditions. The annulus axis is aligned horizontally such that the so called “crescent shape pattern” of two axisymmetric convection cells develop when gravity is present. To apply different gravity conditions the experiment is placed in an

A wind tunnel experimental investigation of the separated flow over a back-facing ramp at 25° slant angle and equipped with an array of slotted synthetic jets (SJs) actuators for active flow control (AFC) has been conducted at height-based, h, Reynolds numbers between 9.41 × 103 ≤ Reh ≤ 2.55 × 104. Both the baseline, i.e. without control, and controlled cases were inspected by means of surface pressure

A high-speed chemiluminescence imaging diagnostic system has been developed and characterized for measuring species-specific properties of spherically expanding flames, with the objective of obtaining synchronized measurements of multiple flame properties from a single flame experiment. The imaging system comprises a high-speed camera coupled to a high-speed image intensifier and optical filters to

Understanding the air injection strategy of a ventilated supercavity is important for designing high-speed underwater vehicles wherein an artificial gas pocket is created behind a flow separation device to reduce skin friction. Our study systematically investigates the effect of flow unsteadiness on the ventilation requirements to form (CQf) and collapse (CQc) a supercavity. Imposing flow unsteadiness

Plasma-assisted combustion (PAC) is a potential method to improve the performances of aero-engine combustion chambers. A plasma-assisted combustion actuator (PACA) that operates without an additional air supply device was designed to improve the performance of the combustion chamber. To validate the feasibility of using the PACA to enhance the annular combustor performance, a plasma-assisted combustion

The aim of this paper is to characterize two-phase phenomena occurring for a rapid energy discharge in the fluid leading to explosive vapour expansion. This study was motivated by the lack of macro-scale experiments characterizing those transient phenomena at high reduced pressure. For that purpose, a complete test section was designed based on the Joule effect to deliver the energy discharge. CO2

Ahmed body; trailing vortices; aspect ratio; time-resolved PIV; spectral POD & The dynamic structures in the wake of the Ahmed body with a 25° slant angle were investigated. It is well established that the wake is dominated by two, counter rotating, streamwise vortex structures (C-pillar vortices). The influence these vortices have on the flow over the slant back was altered by modifying the width

High-spatial-resolution (HSR) two-component, two-dimensional particle-image-velocimetry (2C-2D PIV) measurements of a zero-pressure-gradient (ZPG) turbulent boundary layer (TBL) and an adverse-pressure-gradient (APG)-TBL were taken in the Laboratoire de Mécanique des Fluides de Lille (LMFL) High Reynolds number Boundary Layer Wind Tunnel. The ZPG-TBL has a momentum-thickness based Reynolds number Reδ2=δ2Ue∕ν=7

The influence of buoyancy on pressure oscillation amplitude and frequency was studied with two steam jet directions in the range of steam mass flux 8.34–50.13 kg/(m2·s) and water temperature 40–85 °C. At small steam mass flux, the steam bubble pattern of vertical downward jet is attached bubble regime because the direction of steam momentum and buoyancy are opposite. The pressure oscillation frequency

The flow patterns and the plug hydrodynamics of liquid–liquid two-phase flow in a small circular channel were experimentally investigated. Five distinct flow patterns, including droplet flow, slug flow, throat-annular flow, annular flow and stratified flow were observed in the silicone oil–water system. The flow pattern map was present systematically based on Re, We, water volume fraction and mixture

Lean combustion can greatly improve the thermal efficiency of gasoline engine. Increasing ignition energy and tumble level can effectively expand its application range. Optical glass liner was used to clearly observe the in-cylinder state. Particle image velocimetry(PIV) was used for quantitative evaluation of tumble modification. The integral tumble ratio of the high tumble intake port is 1.67 times

Time-resolved particle image velocimetry is implemented with a camera array and several laser sheets; this results in a multi-spatio-temporal scale system that is modular and flexible. The setup is optimized to capture global flow features, while locally resolving in space and time near the Kolmogorov scale. The apparatus relies extensively on machine vision CMOS cameras; they are inexpensive and stream

In this study, temperature field estimation was performed via time-of-arrival measurements of acoustic waves and using machine learning. An axisymmetric combustion field created by a McKenna burner was chosen as the measurement region. Electrical discharges served as the acoustic point source, and the acoustic travel times were measured using microphones installed along the periphery of the measurement

In this study, spark assisted compression ignition (SACI) combustion was investigated using PRF95 (a low reactivity high octane reference fuel of common commercial gasoline), a mixture of 95% isooctane (by volume) and 5% n-heptane (by volume) with a RON of 95 and compared with pure compression-ignition without spark. Characteristics like the cumulative heat release (CHR) and the heat release rates

Understanding condensation of CO2 is essential for e.g designing compact heat exchangers or processes involved in Carbon Capture and Storage. However, a consistent experimental campaign for condensation of CO2 on common materials is lacking. In this work, we present an experimental method and an associated laboratory setup for measuring the heat transfer properties of CO2 condensation on materials

As one fundamental flow structure, the vortex ring behind an impulsively starting disc can vividly characterize the vortex structure around the flapping flight and the drag-based paddling propulsions. In this paper, an elaborate experiment is performed to investigate the formation of the vortex rings (termed as DVR) by using digital particle image velocimetry (DPIV), as well as by investigating the

Experiments were conducted to measure condensation heat transfer of steam-ethanol mixtures on a horizontal smooth tube. Heat flux and vapor-to-surface temperature difference were accurately measured over a wide range of mass concentration of ethanol (0.001%, 0.005%, 0.01%, 0.025%, 0.05%, 0.1%, 0.5% and 1.0%.) at atmospheric pressure. The present work extends earlier data of Murase et al. (2007) and

The aim of this study was to investigate the effects of installing the grooved and smooth control cylinder upstream of a circular bare cylinder with a focus on the heat transfer and the flow structure behind the bare cylinder. The Reynolds number based on the bare cylinder diameter (D = 50 mm) is Re = 5 000. Control cylinder has a constant diameter as d = 25 mm. Flow characteristics and heat transfer

The initial spreading phenomena of oil droplets on a partially wettable surface under various surrounding pressures was conducted through an experimental investigation outlined in this study. The gauge pressure of the surrounding medium was varied stepwise in the range from atmospheric pressure to 30 MPa. Upon contact with the surface, spreading alters the total energy of the system. The timescale

A spherical particle with a diameter of 25.4 mm and density of 2640 kg/m3 was launched vertically upward toward the free surface of calm water. The Froude number of the particle passing through the water surface was varied. The dependence of the Froude number on the particle motion and water surface behavior was investigated from the instant the particle crossed the water surface until it attained

To clear the effects of the hydrodynamic interactions among neighboring vapor bubbles on the saturated pool boiling heat transfer, artificial nucleation sites with several cavity arrangements were manufactured on the substrate surface and measured liquid temperatures near heated substrate by a miniature thermocouple probe with 10 kHz. The surface temperature of heated substrate was measured by an infrared

This paper presents an experimental study to explore the feasibility of utilizing a swirling inverse diffusion flame (IDF) jet for impingement heating. The investigation concentrates on the impinging flame structure and impingement heat transfer. The effects of air swirling, the air jet Reynolds number, Rea, the global equivalence ratio, Φ, and the non-dimensional burner-to-plate distance, H/da, on

This study experimentally investigates the axial heat transfer of the secondary flow in the cylindrical annular gap around a flywheel within a canned reactor coolant pump, belonging to the Taylor-Couette (TC) flow. A dynamic method based on the transient temperature responses of the TC flow to the input thermal waves, where the axial heat transfer coefficient is determined by the amplitude decay and

Motivated by the importance of spray evaluation of viscous bioliquids prior to their deployments in combustion devices for heat and power generation, an aqueous surrogate was developed using water, glycerol, and a surfactant for nozzle design and optimization purposes. It provides a safe, clean, and transparent alternative for the spray characterization of bioliquids in a laboratory environment, compatible

Variations in fluid temperature are the most important error source in hot-wire anemometer measurements and must sometimes be compensated for. Although many temperature compensation schemes have been proposed over the years, no consensus seems to be reached regarding correction methods. In this paper new precision measurements on heat transfer from heated wires have confirmed that, provided the fluid

The turbulent strain rate generated by a pair of 25.4 mm tall and 12.7 mm wide (W) rectangular strips at a Reynolds number based on the strip width of 8500 was measured using a 3D hotwire probe in a wind tunnel. The strips were placed side-by-side separated by 3 W, 2 W, and 1 W. The convective heat transfer enhancement, denoted by the normalized Nusselt number (Nu/Nu0), was correlated with turbulence

A robust and easy-to-apply automatic static mask generation technique for PIV images is described. The technique is used after background removal operations and requires an image ensemble with sufficient number of single-frame or double-frame PIV images. The technique does not require any prior knowledge of the flow, illumination conditions, the bounding surface, or static object geometry. The technique

The present work is aimed at analyzing changes in the interfacial temperature distribution and interfacial heat flux distribution during sessile droplet evaporation. In particular, two kinds of nonintrusive measurement techniques, temperature-sensitive paint (TSP) and infrared imaging were used simultaneously. TSP was used to capture the interfacial temperature distribution, and then a one-dimensional

CHF is the maximal limit of heat flux in boiling heat transfer, therefore, it is a crucial parameter that has a fundamental impact on the security and economy of the nuclear system. An experimental investigation was carried out in the present study to identify the dominant CHF mechanism in a narrow rectangular channel at different gap sizes (2 mm and 3 mm). The visualization experiments were performed

Mechanisms for controlling the shock wave boundary layer interaction (SWBLI) by a plasma actuator array are investigated by two experiments. Low-frequency and high-frequency actuation modes are compared. The experimental results yield valuable insights into the control mechanism of SWBLI using a surface arc plasma actuator array. The schlieren snapshots and the mean and root mean square error of the

This experimental investigation discusses the effectiveness of shortfin mako shark skin to passively control turbulent boundary layer separation. Experiments were conducted in a water tunnel facility with the shark skin specimens mounted on a smooth flat plate subjected to an adverse pressure gradient. The two skin specimens have shark scales with different sizes, shapes, and bristling angles. The

The local phase distribution of adiabatic air-water two-phase flow in churn-turbulent to annular flows was experimentally investigated using the Two-Sensor Droplet-Capable Conductivity Probe (DCCP-2). The experiments were performed in a 2.54 cm inner diameter vertical round pipe at downward flows. Twelve flow conditions in churn-turbulent to annular flows were chosen for the current study. The inlet

The maldistribution in the parallel multiple channels commonly leads to a reduction in the efficiency of heat exchangers and even causes the equipment to suffer the risk of failure. The distribution of gas–liquid two-phase slug flow when moving through the parallel multiple channels is still an unresolved problem and limited by the lack of experimental data. This work presents an experimental study

The magnitude of surface heat flux and its accurate estimation are very crucial owing to their applicability in impulsive thermal loads for high-speed flights. The correctness of such heat flux is associated with the implications from highly responsive thermal sensors in ground-based aerodynamic studies. In the present study, the performance effectiveness of an indigenous, in-house-made coaxial thermal

Condensation of steam at a low mass flux inside an inclined tube was experimentally investigated to aid the optimal design of air-cooled passive heat exchangers for advanced LWRs. While varying downward inclination angle from 0 to 90°, the heat transfer coefficient monotonically improved by more than 15% while previous studies that have used refrigerants have reported that the optimal angle is between

Abstract The formation and evolution of volumetric flow structures from a rectangular orifice synthetic jet ( AR = 10 , Re = 550 , Sr = 0.0117 , and L o = 0.0855 m ) impinging on a flat plate is investigated using phase-locked single-camera light-field particle image velocimetry (LF-PIV). An impinging plate is located 24 orifice widths away from the rectangle orifice and this volumetric flow data is

Abstract Flow dynamics of a two-dimensional liquid sheet injected transversely into a subsonic airstream was comprehensively investigated. An injector with an aspect ratio of 90 and a thickness of 0.35 mm was used to produce the two-dimensional liquid flow. Experimental visualizations were used to identify the main features of the liquid sheet in crossflow. Tests were conducted for a wide range of

Abstract We report a systematic experimental study to characterise the isothermal flow-field within a vortex-based solar cavity receiver with an open aperture. Measurements were performed using particle image velocimetry for a fixed flow rate through the inlet jets to achieve Reynolds number of ReD = 11800. A range of flowrates through the outlet were assessed for a fixed inlet flow rate, including

Abstract We experimentally explored the distinct effects induced by the geometry of various axisymmetric orifices in the near and intermediate regions of jets at a Reynolds number of Re ≈ 10 5 based on the diameter, d = 10 mm, of the orifices. The orifices inspected had thicknesses of ∊ / d = 0.2 , 1 and 2 and divergence angles of θ = 0 ∘ , 20 ∘ and 45 ∘ . High-speed planar particle image velocimetry

Abstract An experimental study of a simple NACA 0012 airfoil fitted with two different flap profiles was carried out to characterize their aerodynamic and aeroacoustic performance. The airfoil with a flap deflection angle of β = 10 ° was tested for a wide range of angles of attack at a chord-based Reynolds number of Re c = 2.6 × 10 5 . The aerodynamic lift and drag measurements show improved lift-to-drag

The denoising of Lagrangian trajectories based on regularized B-spline is investigated. The aim is to find systematic criteria for optimization of algorithms used in 4D-PTV in order to optimize the quality of 4D-PTV measurements of turbulent flows as well as high-order of turbulence statistics. We introduce and adapt to this context two innovative tuning strategies which are commonly used in the Tikhonov

Natural convection heat transfer from three isothermally heated horizontal cylinders submerged in water in a triangular arrangement is investigated. Two configurations, named here as one over two and two over one, are characterised for three cylinder spacings (S = 2, 3 and 4 cylinder diameters) and Rayleigh number conditions (Ra = 2×106, 4 × 106 and 6 × 106). Combined local heat flux measurements and

The current work presents a study of qualitative relationships between the flow unsteadiness, induced by nozzle geometry variation, and non-equilibrium condensation behavior at high temporal scales for supercritical carbon dioxide (sCO2) flow. A closed sCO2 loop facility is used to drive a supercritical carbon dioxide flow through a rectangular converging–diverging channel. As the flow traverses through

The combustion of an oxygen/paraffin hybrid rocket motor was experimentally characterized. Firing tests were conducted for different oxidizer mass fluxes ranging from 2.47 to 3.40 g/ (cm2·s). Variations in temperature and H2O partial pressure at the nozzle exit were diagnosed using mid-infrared tunable diode laser absorption spectroscopy (TDLAS) based on H2O absorption near 2.5 μm. Three H2O absorption

Coupling structures of buoyancy induced thermal convection in two immiscible layers with and without weak background rotation were investigated in laboratory experiments using a glycerol solution and a silicon oil as the test fluids. A cylindrical vessel was employed to yield three-dimensional (3D) development of the two-layer convection, and the influence of background rotation on convective motion

In this study, the placement of a micro-vortex generator (VG) upstream of the film cooling hole is proposed to improve the film cooling performance. The film cooling effectiveness and flow characteristics at three blowing ratios (M = 0.2, 0.4, and 0.8) are measured by using pressure-sensitive paint (PSP) and particle image velocimetry (PIV), respectively. The results indicate that the VG upstream of

Two-phase pressure drop is studied in a transparent cross-corrugated channel for uniform and non-uniform gas–liquid distribution. Both uniform and non-uniform distribution are created by injecting air and water through different numbers of nozzles directly into the channel. The frictional pressure drop clearly indicates the impact of maldistribution. The single channel is pivot-mounted to allow horizontal

Hydraulic jumps occur commonly in natural channels and energy dissipation systems of hydraulic structures in the violent transition from supercritical to subcritical flows. They are characterised by large flow aeration, high turbulence and strong fluctuations of the free surface and the jump toe. For free surface measurements, fast-sampling, fixed-point instruments such as acoustic displacement meters