James A. Liburdy

• Professor at Oregon State University

An experimental study was undertaken to evaluate the power extraction of an airfoil undergoing large amplitude pitching and heaving using a trailing edge flapping motion for the application of energy harvesting for steady flow over the airfoil. The airfoil was a NACA0015 design, pitching at the 1/3 chord position, with an actively controlled traili...

The purpose of this work is to provide empirical design models for low-pressure, subsonic Venturi nozzles. Experimentally validated simulations were used to determine the effect of nozzle geometry and operating conditions on the suction ratio (ratio of suction mass flow rate to motive mass flow rate) of low-pressure, subsonic Venturi nozzles, over...

A leading-edge vortex initiation criterion of an oscillating airfoil is shown to provide a means to predict the onset of leading-edge separation. This result is found to collapse the occurrence of separation during the oscillation cycle when scaled using the leading-edge shear velocity determined from the foil oscillating kinematic motion. This is...

Transition to turbulence in randomly arranged porous media is observed in nature and industrial applications. The flow characteristics of these flows during transition are not well identified. This work describes the parameters influencing on overall mixing during the transition process from the perspective of scale of vortical structures and dispe...

Pore-scale observation of vortical flow structures in porous media is a significant challenge in many natural and industrial systems. Vortical structure dynamics is believed to be the driving mechanism in the transition regime in porous media based on the pore Reynolds number, $Re_p$. To examine this assertion, a refractive-index matched randomly p...

The energy harvesting performance of a flapping airfoil is studied through discrete vortex model. Results are obtained for a thin flat airfoil that undergoes a sinusoidal flapping motion for reduced frequencies of k = fC/U∞ = 0.06–0.16 where f is the heaving frequency of the foil, C is the chord length and U∞ is the freestream velocity. The airfoil...

This study explores the feasibility of using the vortex impulse approach, based on experimentally generated velocity fields to estimate the energy harvesting performance of a sinusoidally flapping foil. Phase-resolved, two-component particle image velocimetry measurements are conducted in a low-speed wind tunnel to capture the flow field surroundin...

The effects of passive, inertia-induced surface flexibility at the leading and trailing edges of an oscillating airfoil energy harvester are investigated experimentally at reduced frequencies of k = fc/U∞ = 0.10, 0.14, and 0.18. Wind tunnel experiments are conducted using phase-resolved, two-component particle image velocimetry to understand the un...

The vortex dynamics and lift force generated by a sinusoidally heaving and pitching airfoil during dynamic stall are experimentally investigated for reduced frequencies of \(k = fc/U_{\infty } = 0.06{-}0.16\), pitching amplitude of \(\theta _0 = 75^\circ\) and heaving amplitude of \(h_0/c = 0.6\). The lift force is calculated from the velocity fiel...

The flow characteristics in the inertial Reynolds number regime are investigated in a mono-dispersed random pack porous media. Time-resolved particle image velocimetry (PIV) is used to visualize the velocity field in a low aspect ratio bed with 15 mm glass beads. An aqueous solution of Ammunium Thiocynante is used as the working fluid to facilitate...

Energy harvesting performance for a flapping foil device is evaluated to determine how activated leading edge motion affects the aerodynamic forces and the cycle power generated. Results are obtained for a thin flat foil that pitches about the mid-chord and operates in the reduced frequency range of k = fc/U of 0.06–0.10 and Reynolds numbers of 20,...

The influence of vortex dynamics on the force production of a heaving and pitching foil operating in the energy harvesting regime is studied experimentally using 2C-PIV. Results are obtained for reduced frequencies in the range of k = fc/U = 0.06 to 0.14. The flow induced vertical force-time history during cyclic operation is evaluated from PIV dat...

An experimental investigation is conducted to study the leading edge vortex (LEV) evolution of a simultaneously heaving and pitching foil operating in the energy harvesting regime. Two dimensional particle image velocimetry measurements are collected in a wind tunnel at reduced frequencies of k = fc/U = 0.05–0.20. Vorticity flux analysis is perform...

The aerodynamic performance of an oscillating pitching and plunging foil operating in the energy harvesting mode is experimentally investigated. Experiments are conducted in a closed-loop recirculating wind tunnel at Re of 24,000 to 48,000, and reduced frequencies (k) of 0.04 to 0.08. Foil kinematics are varied through the following parameter space...

The transient regime of flow through randomly packed porous media has been observed experimentally from steady inertial to turbulent flow. The accurate method of two component time-resolved particle image velocimetry is utilized in a randomly packed ordered array of spheres in which the refractive index of the solid phase is matched with the fluid...

Expanding gas such as in a piston–cylinder configuration is of considerable interest in power cycles in determining work during the process. In general, there can be considerable energy lost during expansion by heat transfer to the cylinder walls. This is a rather complex heat transfer process despite the rather simply geometry as the gas goes thro...

An experimental study was conducted to explore the effect of surface flexibility at the leading and trailing edges on the near-wake flow dynamics of a sinusoidal heaving foil. Mid-span particle image velocimetry measurements were taken in a closed loop wind tunnel at a Reynolds number of 25,000 and at a range of reduced frequencies (k = fc/U) from...

An experimental study was conducted to explore the effect of surface flexibility at the leading and trailing edges on the near-wake flow dynamics of a sinusoidal heaving foil. Midspan particle image velocimetry (PIV) measurements were taken in a closed-loop wind tunnel at a Reynolds number of 25,000 and at a range of reduced frequencies (k = fc/U)...

Spatio-temporal cooling of electronics using latent energy might be achieved by closely spaced, rapid departure of small bubbles. One means to achieve small diameters during boiling is to provide an additional upward force during bubble formation, such as that from vapor extraction. Experiments were conducted of bubble extraction using constant flo...

Obtaining highly-resolved velocity data from experimental measurements in porous media is a significant challenge. The goal of this work is to compare the velocity fields measured in a randomly-packed porous medium obtained from particle image velocimetry (PIV) with corresponding fields predicted from direct numerical simulation (DNS). Experimental...

The results of an experimental study to determine the smallest, dissipative scales of the turbulent flow in a randomly packed porous bed are presented and discussed. Particle Image Velocimetry was used to obtain time dependent two-dimensional velocity fields within the bed, which were then used to obtain turbulent statistical measures within the fl...

Both experimental and computational methods applied to the study of porous media flows are challenging due to the complex multi-phase geometry and ability to resolve scales over a reasonably large domain. This study compares experimentally obtained results based on refractive index matching of detailed velocity field vectors with those obtained usi...

This study examines the use of a passively actuated trailing edge of a thin wing during oscillation motion. The integration of a flexible trailing edge with an oscillating wing has the ability to alter the transient lift and drag characteristics, as well as the time averaged values. The results are obtained for a chord-length based Reynolds number...

There are several applications wherein high-heat-flux thermal transport is crucial to the reliable operation of devices, to increased efficiency of processes, and for miniaturization. Heat transport through microchannels provides an attractive method of removing such high heat fluxes. This chapter describes the basic theory of microchannel fluid fl...

A major detriment of two-phase microscale flow systems is a relatively high pressure drop, as well as the potential for flow instabilities. A possible mechanism to overcome these disadvantages is vapor extraction through a hydrophobic porous wall in the channel to reduce vapor content and suppress vapor expansion. The vapor extraction may occur eit...

An experimental study was undertaken to explore the evolution of flow structures and their characteristics within a randomly packed porous bed with particular attention to evaluating turbulent scalar dispersion. A low aspect ratio bed of 4.67 (bed width to spherical solid phase particle diameter) with fluid phase refractive index matched to that of...

Turbulent porous media flows are encountered in man-made systems such as catalytic bed reactors and advanced heat exchangers. Dispersion experienced by a scalar in these flows play an essential role in the overall efficiency and performance of these systems. In an effort to understand turbulent flows in such complex geometry, time resolved PIV meas...

Understanding the behavior of commercially available hydrophobic polymer membranes is important for applications where separating a gas (or vapor) from a two-phase mixture with liquid is beneficial. For example, in-situ vapor extraction can be used in microscale heat sinks to improve heat transfer and flow stability. In this paper, two working flui...

The pressure drop penalty of convective boiling flow in microchannels may be exceedingly large. A proposed method of reducing this penalty is to extract vapor locally along the channel. A potential consequence of this extraction is that the local void fraction reduction positively influences the local heat transfer coefficient. In this study, a one...

An experimental study was undertaken to better understand the turbulent flow characteristics within a randomly packed porous bed. A relatively low aspect ratio bed (bed width to spherical solid phase particle diameter of 4.67) with the fluid phase refractive index matched to that of the solid phase was used to obtain time resolved particle image ve...

Low aspect ratio porous beds (bed width to bead diameter) have engineering applications such as catalytic reactors, combustors and heat exchangers. The nature of the packing within the bed and the influence of the near-wall region especially for randomly packed beds are expected to affect the velocity field and consequently the statistical characte...

Application of optical techniques such as PIV, PTV, and LDA for velocity field estimation in porous media requires matching of refractive indices of the liquid phase to that of the solid matrix, including the channel walls. The methods most commonly employed to match the refractive indices have been to maximize the transmitted intensity through the...

An experimental study on the turbulent flow characteristics in a randomly packed porous bed is presented and discussed. Time resolved PIV measurements, taken in specific pore spaces are used to evaluate transitional and developed turbulent flow statistics for pore Reynolds numbers from 54 to 3964. Three different regimes of steady laminar, transiti...

The present work shows the potential of using a diverging channel with in-situ vapor extraction as a means to reduce flow instability in microscale flow boiling. It has been shown that diverging channel helps stabilize convective boiling flow. In-situ vapor extraction is proposed as an alternative method that helps further stabilize flow boiling. T...

This study is an experimental investigation of the turbulent flow structure in randomly packed porous bed made with uniform sized spheres. Results are based on time resolved, two component PIV measurements in individual pore spaces of the bed. Data are presented for pore Reynolds number range of 54–3964. Three different flow regimes are identified,...

Direct numerical simulations were performed to study the effect of an elastically mounted trailing edge actuator on the unsteady ow over a plunging, thin airfoil at Reynolds num- ber of 14700 based on the chord length. The goal is to investigate potential benefits of ow-induced passive actuation of the trailing edge to the lift and drag characteris...

Inertial flows in porous media occur in both natural (e.g., at stream bed interfaces with the hyporheic zone) and engineered (e.g., near well bores or in packed-bed reactors) systems. There are a number of approaches for representing the inertial effects of flow in a porous medium, and most commonly these laws relate the pressure gradient to the sq...

The measurement of flow in porous media is challenging due to accessibility and large range of flow passage scales. The use of PIV requires matching of refractive indices of fluid and solid phases. Slight mismatches are shown to cause significant tracking errors. In gaining PIV data at discrete planar locations along the optical axis, variations oc...

The flow characteristics of distinct flow regimes in porous media and the evolution with Reynolds number is poorly understood at high Reynolds numbers. Typical means of measurement are MRI imaging, PTV and PIV, the latter two require refractive index matching. This study presents PIV measurements in a porous bed of spherical beads, for pore Reynold...

In the present study, spray cooling curves are presented for two micro-structured surfaces and are compared to smooth surface results. The micro-structured surfaces consisted of bio-inspired fractal-like geometries, denoted as grooves or fins, extending in a radial direction from the center to the periphery of a 37.8 mm circular disc. Depending on...

Experimental results of adiabatic boiling of water flowing through a fractal-like branching microchannel network are presented and compared to numerical model simulations. The goal is to assess the ability of current pressure loss models applied to a bifurcating flow geometry. The fractal-like branching channel network is based on channel length an...

Use of oscillatory actuation of the leading edge of a thin, flat, rigid airfoil, as a potential mechanism for control or improved performance of a micro-air vehicle (MAV), was investigated by performing direct numerical simulations and experimental measurements at low Reynolds numbers. The leading edge of the airfoil is hinged at 30% of the chord l...

Experimental measurements in a porous media flow are extremely challenging due to the highly three dimensional nature of the flow, probe access, the wide range of flow channel characteristic lengths and the wide dynamic range of velocities, especially at relatively high Reynolds number flow conditions. One method that has been used and is being fur...

This study examines the hydrodynamics and temperature characteristics of distilled deionized water droplets impinging on smooth and nano-structured surfaces using high speed (HS) and infrared (IR) imaging at We = 23.6 and Re = 1593, both based on initial drop impingement parameters. Results for a smooth and nano-structured surface for a range of su...

Spatial and temporal variations of channel wall temperature during flow boiling microchannel flows using infrared thermography are presented and analyzed. In particular, the top channel wall temperature in a branching microchannel silicon heat sink is measured non-intrusively. Using this technique, time-averaged temperature measurements, with a spa...

Experimental flow visualization in porous media is often conducted using optical techniques such as PIV and PTV for velocity field estimation and LIF for concentration field measurements. The porous bed is made optically accessible to laser light and imaging by matching refractive indices of the liquid phase to that of the solid matrix, including t...

The ability to perform particle image velocimetry (PIV) in porous media presents many challenges in order to minimize the inherent errors in the process. Index of refraction matching is one method to visualize the entire region of interest. One important question is the available signal to noise ratio when using an index of refraction technique tha...

The use of two phase cooling strategies for high power microelectronics has been being widely investigated in order to better control desired operating temperatures and to reduce the mass flow rates required for cooling. However, disadvantages arise when considering the potential for unstable flow conditions and high pressure drop penalties associa...

This study investigates the hydrodynamic characteristics of droplet impingement on heated surfaces and compares the effect of surface temperature when using water and a nanofluid on a polished and nanostructured surface. Results are obtained for an impact Reynolds number and Weber number of approximately 1700 and 25, respectively. Three discs are u...

Two-phase air–water flows in a microscale fractal-like flow network were experimentally studied and results were compared to predictions from existing macroscale void fraction correlations and flow regime maps. Void fraction was assessed using (1) two-dimensional analysis of high-speed images (direct method) and (2) experimentally determined using...

Droplet formation from a flexible nozzle plate driven by a prescribed-waveform excitation of a piezoelectric is numerically investigated using a computational fluid dynamics (CFD) model with the volume of fluid (VOF) method. The droplet generator with a flexible nozzle plate, which is free to vibrate due to the pressure acting on the plate, is mode...

Convective boiling and gas-liquid flows in branching microscale flow networks within disk-shaped heat sinks were studied experimentally. Void fraction and flow regime variations as a function of branch level were reported for gas-liquid flows and compared with existing void fraction correlations and regime maps, respectively. Two methods for assess...

This study focuses on the detection and characterization of vortices in low Reynolds number separated flow over the elliptical leading edge of a low aspect ratio, flat plate wing. Velocity fields were obtained using the time-resolved particle image velocimetry. Experiments were performed on a wing with aspect ratio of 0.5 for velocities of 1.1 m/s,...

The pressure drop of convective boiling flow may be reduced by extracting vapor locally since the entire generated vapor does not have to travel through the entire channel length. In this study, the theoretical model was developed to simulate a convective boiling flow through a fractal-like branching microchannel network with vapor extraction. The...

The flow structure around a low aspect ratio wing at low Reynolds numbers and a fixed angle of attack of 20° is discussed using flow visualization as well as Three-Component Time-Resolved Particle Image Velocimetry (3C TR PIV). Mean quantities and statistical measurements of velocity were obtained and used to describe the average and transient char...

Many applications would benefit from an understanding of the physical mechanism behind fluid movement on rough surfaces, including the movement of water or contaminants within an unsaturated rock fracture. Presented is a theoretical investigation of the effect of surface roughness on fluid spreading. It is known that surface roughness enhances the...

Controlling flow in an unsteady separating flow requires accurate information about the surface forces and the effect that vortical structures in the flow field have on those surface forces. A correlation between vortex passage and surface pressure is defined to determine appropriate locations for sensors on the surface of a square cylinder for con...

Micro-droplet formation from a passive vibrating micro-nozzle driven by a pulsed pressure wave is numerically simulated. The micro-nozzle is formed from an orifice in a thin walled plate that is allowed to freely vibrate due to the pressure loading on the plate. The analysis couples the fluid flow from the nozzle and the resultant droplet formation...

This study investigates the flow over a flat airfoil of low aspect ratio using experimental, time-resolved particle image velocimetry methods. The flow conditions are characterized by low Reynolds flow at two relatively high angles of attack, 15° and 20°. A high pass Gaussian filter was employed to help identify structures within the flow field. Al...

This study examines the ability to detect the dynamic interactions of vortical structures generated from a Helmholtz instability caused by separation over bluff bodies at large Reynolds number of approximately 104 based on a cross stream characteristic length of the geometry. Accordingly, two configurations, a square cylinder with normally incident...

Very complex flow structures occur during separation that can ap-pear in a wide variety of applications involving flow over a bluff body. This study examines the ability to detect the dynamic interactions of vortical struc-tures generated from a Helmholtz instability caused by separation over bluff bodies at large Reynolds number of approximately 1...

This study focuses on the dynamics of water and nanofluids droplet surface impingement. Droplets are generated by a piezoelectric driven droplet generator. A high-speed-high-resolution camera is used to record droplets impacting on a smooth heated silicon surface. Droplet impact velocity, spreading diameter, spreading height and dynamic contact ang...

Quantitative measurement of channel wall temperature in two-phase microchannel flows using infrared thermography is discussed. In particular, the top channel wall temperature of a branching microchannel silicon heat sink is presented. Quantitative temperature measurements require several considerations in the design and fabrication of the heat sink...

This study evaluates flow instability and void fraction in a fractal-like branching microchannel network. The flow network is characterized by set branching ratios for channel length and width of 1/2 and 2, respectively, and features five branching levels. The hydraulic diameter of the channels ranged from 308μm at the inlet to 143μm at the outlet....

In this study the flow characteristics over a fixed surface, flat, low aspect ratio thin wing are investigated. Of interest is the dynamic separation process for a range of angle of attacks, and chord Reynolds numbers, particularly the time dependent nature of the vortex development, convection and interactions. Angle of attack is varied from 14 to...

Based on predictions of lower pressure drop penalties in fractal-like branching channels compared to parallel channels, an experimental investigation of two-phase void fraction variations was performed. The flow network, mimicking flow networks found in nature, was designed with a self-similar bifurcating channel configuration and etched 150 μ m in...

Fractal-like branching channels are proposed for a number of microscale applications, including heat sinks, heat exchangers, absorbers, desorbers, and micro-mixers. Based on model predictions, the benefit of fractal-like channel designs is a lower pressure drop than parallel straight channels for a given flow rate, when compared to an equal channel...

The flow structure generated by circular and oblate shaped nozzles for an impinging confined 7-by-7 jet array is investigated. Instantaneous velocity fields, obtained from Digital Particle Image Velocimetry (DPIV) along the crossflow direction are analyzed using Proper Orthogonal Decomposition (POD). Also, a vortex detection algorithm is used to lo...

This study examines the generation of large scale vortices caused by flow separation from a flat wing at various angles of attack. Time-resolved particle image velocimetry is used to determine the evolution and convective characteristics of the large scale structures. A rectangular airfoil with aspect ratio of 0.5 is used and data are collected at...

Successive droplet impingement onto a solid surface is numerically investigated using a CFD multiphase flow model (VOF method). The main focus of this study is to better understand the hydrodynamics of the non-splash impingement process, particularly the effect of a dynamic contact angle and fluid properties along with the interaction between succe...

This is a work in progress. The objective of the present work is to develop techniques for assessing velocity deficits in branching microchannel networks. Liquid velocity distributions were acquired using μPIV in gas-liquid flows through the initial branch in a fractal-like branching microchannel flow network. Gas interface velocities were determin...

For a piezoelectric stack (PZT) driven droplet generator, the driving waveform and driving frequency effects on liquid filament shape and droplet characteristics have been studied. A lumped element model (LEM) is developed to study the acoustic-mechanical behavior and the volumetric rejection of the droplet generator. Based on the LEM, the PZT disp...

This study focuses on the detection and characterization of vortices in low Reynolds number separation flow over the elliptical leading edge of a flat plate airfoil. Velocity fields were obtained using Time Resolved Particle Image Velocimetry (TRPIV). The Reynolds number based on chord length ranged from 14,700 to 66,700. Experiments were performed...

Increases in pressure due to vapor generation during boiling in microchannels can be reduced by extraction of vapor at its point of inception. Ultimately, this local vapor extraction decreases the pressure drop required to drive the flow through the microchannel network within the heat sink. Indeed, by lowering the overall flow rate by vapor extrac...

Area-averaged void fraction images of convective boiling in a branching channel heat sink were acquired with a high speed high resolution camera at a rate of 1,000 frames per second for one second. Data sets are limited by the buffer size of the camera. Test conditions include a flow rate of 30 g/min, 30 W of energy added, and a subcooling of appro...

The concept of a confined thin film to enhance the desorption process is based on a reduced mass diffusion resistance. A wide thin film is formed into a microchannel by using a porous membrane as one wall of the channel enabling vapor extraction along the flow. Heat added to the channel results in vapor generation and subsequent extraction through...

The vortical structure associated with a streamwise 45° inclined pulsed jet in a crossflow is investigated. Using Stereo-PIV data, a vortex detection algorithm and Proper Orthogonal Decomposition (POD), this study exposes the interaction of longitudinal vortices rollup in the jet shear layers and a large spiral rollup known as the counter rotating...

Microbubble drag reduction has been observed in high Reynolds number turbulent flows. The interaction of microbubbles with the viscous sublayer seems to be of interest. In this study a microchannel on the order of 100 microns was used to simulate the shear rate of the near-wall region of a high Re flow. The interaction of the fluid flow with microb...

Sonic anemometers–thermometers (SATs) are robust instruments used in numerous research and analytical micrometerological studies. The accuracy and precision of the measured mean and turbulent fluctuations of wind speed and temperature are unknown across a range of ambient conditions and among different model SATs. Here, we compared quantities from...

The flow and heat transfer characteristics of confined jet array impingement with crossflow is investigated. Discrete impingement pressure measurements are used to obtain the jet orifice discharge flow coefficient. Digital particle image velocimetry (DPIV) and flow visualization are used to determine the flow characteristics. Two thermal boundary c...

A micropump was developed for a fluidic system that requires fluid transport in the 100+ μL/min flow range. The constraints on the design included the ability to control the flow rate over a reasonable range of flow rates, operate at fairly high pressure loads, and non-contact of the working fluid with the pump actuation system. The design was base...

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Single-phase and two-phase flows in microscale fractal-like branching flow networks are studied using a one-dimensional model that includes variable property and developing flow effects. Pressure drop, pumping power, changes in the bulk fluid temperature and a performance parameter are reported for mass flow rates ranging from 25 to 500 g/min and w...

The oscillatory free-surface displacement in an orifice periodically driven at the inlet is studied. The predictions based on a potential flow analysis are investigated in light of viscous and large curvature effects. Viscous effects near the wall are estimated, as are surface viscous energy loss rates. The curvature effect on the modal frequency i...

A sensitive biosensor (cytosensor) has been developed based on color changes in the toxin-sensitive colored living cells of fish. These chromatophores are highly sensitive to the presence of many known and unknown toxins produced by microbial pathogens and undergo visible color changes in a dose-dependent manner. The chromatophores are immobilized...

A computational model is developed to study the effects of alumina layer formation on an ablative surface, when exposed to high temperature particle laden gas flow. The one-dimensional model is developed taking into consideration the thermal loading, particle loading and the temperature dependence of the thermo-physical properties of alumina. A ful...

The diffusion and flow development characteristics of two co-flowing, laminar streams in a high aspect ratio rectangular micro-channel have been examined. A long, thin splitter plate initially separates the two streams such that fully developed flow in each of the two channels is established prior to merging. The co-flowing micro-channel has an asp...

An experimental study is presented in which ammonia is desorbed from a binary mixture of ammonia and water using a network of microscale fractal-like branching channels. The objectives of the study are (1) to determine feasibility of desorption by boiling the fluid mixture inside a microchannel array, and (2) to quantify the rate of desorption as a...

A scheme to achieve high desportion rates in a microscale system has been conceived based on the use of a hydrophobic porous membrane forming one wall of a high aspect ratio channel. To accomplish desorption, vapor is drawn through the membrane, during the addition of heat, as the binary mixture flows along the channel. The channel geometry is desi...

A computational study is presented of the heat transfer performance of a micro-scale, axisymmetric, confined jet impinging on a flat surface with an embedded uniform heat flux disk. The jet flow occurs at large, subsonic Mach numbers (0.2 to 0.8) and low Reynolds numbers (419 to 1782) at two impingement distances. The flow is characterized by a Knu...

Micro-fluid mixing is an important aspect of many of the various micro-fluidic systems used in biochemical production, biomedical industries, microenergy systems and some electronic devices. Active or highly effective passive mixing techniques are often required. In this study, two pulsed injectors are used to actively enhance mixing in a high aspe...

The effectiveness of a direct fire penetrator projectile equipped with an actively controlled rain air actuation mechanism is investigated through dynamic simulation. The ram air control mechanism consists of a rotary sleeve valve which directs air flow from an inlet in the center of the nose to side ports. The coupled dynamics of the projectile, i...