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Intake

Intake is the act or process of taking something into a system, body, or enclosure, often referring to the introduction of fluids, air, food, or other substances.^[1] It can also denote the specific opening or structure through which this occurs, such as an inlet for air or water, or the quantity or amount taken in during that process.^[2] In various fields, the term encompasses critical functions: in engineering, it describes mechanisms like air intake systems in engines that channel fluid for operational efficiency.^[3] In automotive and mechanical engineering, intake systems are engineered to optimize the flow of air or fuel mixtures into combustion chambers, enhancing performance and efficiency while filtering out contaminants.^[4] These systems typically include components like air filters, manifolds, and valves, designed to handle pressure differentials and environmental factors.^[5] In civil and environmental engineering, intake structures serve as gateways for withdrawing water from sources like rivers or reservoirs, ensuring safe conveyance to treatment facilities while preventing debris entry.^[6] Overall, the concept of intake underscores the foundational role of input in sustaining mechanical and operational systems.

General Principles

Function in Fluid Systems

In fluid systems, an intake serves as the primary entry point for air or other fluids into combustion or propulsion systems, such as engines, where it ensures a controlled supply of the working fluid by regulating its volume, pressure, and temperature to optimize system performance. These principles also apply more broadly to other fluid-handling systems, such as water intakes in civil engineering or air intakes in ventilation, though specifics vary by application.^[4] This regulation protects the system from environmental contaminants like dust, rain, or ice while directing the fluid toward the combustion chamber or turbine, maintaining steady flow conditions essential for efficient energy conversion.^[4] Key physical principles govern intake operation, including Bernoulli's principle, which describes the inverse relationship between fluid velocity and pressure in the intake flow, allowing designers to predict and manage pressure drops as air accelerates through constrictions like manifolds or inlets.^[7] A critical metric is volumetric efficiency, defined as the ratio of the actual volume of air (or fluid) drawn into the cylinder during the intake stroke—measured at atmospheric conditions—to the engine's theoretical displacement volume, which quantifies how effectively the intake fills the combustion space and influences power output.^[8] The intake plays a vital role in combustion by delivering oxygen-rich air that mixes with fuel to sustain the chemical reaction, with excess air ensuring complete oxidation and minimizing emissions like unburned hydrocarbons.^[9] To prevent backflow of exhaust gases into the intake, which could dilute the charge and reduce efficiency, one-way valves—such as reed or poppet valves—direct unidirectional flow during the intake phase.^[9] The mass flow rate through the intake, a fundamental parameter for sizing and performance, is given by the equation

\dot{m} = \rho A v

where \dot{m} is the mass flow rate, \rho is the fluid density, A is the cross-sectional area of the intake, and v is the flow velocity; this relation highlights how adjustments in area or velocity directly impact the fluid delivery to the system.^[10] Historically, the function of controlled fluid intake was first recognized in late 18th-century steam engines, where mechanisms like throttling governors managed steam admission to cylinders for efficient expansion. By the early 1900s, these principles evolved to air intake systems in internal combustion engines, adapting governor controls to regulate air-fuel mixtures as steam power gave way to gaseous fuels.

Design Considerations

In the design of intake systems for fluid-handling applications, aerodynamic factors play a critical role in optimizing performance by minimizing pressure losses and enhancing flow efficiency. Smooth geometries, such as rounded inlet lips and gradual expansions, reduce turbulence and boundary layer separation, thereby lowering total pressure recovery penalties. Diffusion processes are incorporated to decelerate incoming air velocity while recovering static pressure, often achieving pressure recovery coefficients above 0.95 in well-designed diffusers through controlled area increases that prevent flow separation.^[11] Thermal management is essential to preserve air density and maximize charge mass, particularly in systems exposed to heat sources. Insulation materials, such as ceramic coatings or foam liners, are applied to intake ducts to limit heat transfer from adjacent hot components. In boosted configurations, intercoolers utilizing air-to-air or air-to-liquid heat exchangers reduce charge air temperatures post-compression, mitigating knock tendencies and enhancing volumetric efficiency without excessive pressure drops.^[12] Material selection influences durability, weight, and operational efficiency across diverse environments. Composite materials, including carbon fiber-reinforced polymers or nylon-based laminates, enable significant weight reductions compared to aluminum equivalents while maintaining structural integrity under vibrational loads in high-performance setups. For corrosive conditions, such as those involving saline exposure, materials like fiberglass-reinforced epoxies or stainless steel alloys (e.g., 316L) provide enhanced resistance to pitting and crevice corrosion. Design constraints require careful balancing of airflow requirements against secondary performance factors like acoustics and cleanliness. High flow rates, necessary for peak power, must be reconciled with noise attenuation using side-branch resonators or perforated inserts, which can suppress broadband intake noise by 10-20 dB across 100-500 Hz frequencies without exceeding 2-3% flow restriction.^[13] Filtration elements, typically pleated media or cyclonic separators, are integrated to capture particulates greater than 5-10 μm, achieving 95-99% removal efficiency while limiting pressure drops to under 1 kPa at rated flows to avoid compromising overall system throughput.^[14] Efficiency metrics quantify intake performance relative to theoretical ideals, guiding iterative design improvements. Intake efficiency is commonly expressed as the percentage of ideal mass flow achieved, often ranging from 85-98% in optimized systems, where deviations arise from frictional and separation losses in ducts and valves. Turbulent flow analysis relies on the Reynolds number (Re = \frac{\rho v D}{\mu}), where \rho is fluid density, v is velocity, D is characteristic diameter, and \mu is dynamic viscosity; values exceeding 10^4-10^5 indicate fully turbulent regimes prevalent in intake flows, necessitating CFD modeling for accurate loss predictions.^[15] A key challenge in intake design is throttle body sizing to align with operational RPM ranges, ensuring adequate airflow without excessive restriction at low speeds or surging at high speeds. Diameters are typically scaled to match peak engine demands—e.g., 40-60 mm for 1-2 L displacements—yielding volumetric efficiencies above 90% across 2000-6000 RPM, but mismatches can reduce efficiency by 5-15% due to choking or inertial mismatches.^[16]

Automotive Applications

Air Intake Manifolds

An air intake manifold is a component in internal combustion engines that distributes incoming air (or air-fuel mixture in carbureted systems) from the throttle body to the individual cylinders for combustion. In modern road vehicles, manifolds are designed to optimize airflow distribution, ensuring even cylinder filling to maximize efficiency and power output. There are two primary types: plenum-style manifolds, which use a large central chamber to provide uniform pressure and even distribution across all cylinders, suitable for a broad range of engine speeds; and tuned-length runner manifolds, which employ runners of specific lengths to create intake resonance pulses that enhance volumetric efficiency at particular RPM ranges, such as low-end torque or high-end power. Key components of an air intake manifold include the runners—tubular passages that channel air to each intake port—and integration with the throttle body, which regulates airflow volume based on accelerator input. Many advanced designs incorporate variable-length mechanisms, such as switchable runners or flaps, to adapt the intake path length dynamically; for instance, variable-length intake manifolds, such as BMW's DISA system introduced in 1992 or Honda's implementations in the 1990s, switch between short and long runners for improved performance across RPM bands. These mechanisms often rely on vacuum actuators or electronic solenoids controlled by the engine management system. The integration of fuel injection systems significantly influences manifold design. In port fuel injection (PFI), fuel is injected into the intake runners just before the intake valves, requiring manifolds with smooth, voluminous paths to promote thorough air-fuel mixing and prevent fuel puddling on cold walls. Conversely, direct injection (GDI) systems inject fuel directly into the combustion chamber, allowing manifolds to focus solely on air distribution without mixing concerns, often resulting in more compact designs with tuned acoustics for better charge motion. This shift has enabled higher compression ratios and efficiency in GDI engines but demands precise airflow management to avoid issues like incomplete cylinder filling. Performance impacts of intake manifold design are closely tied to charge filling efficiency, where the plenum volume plays a critical role. For naturally aspirated engines, rules of thumb suggest a plenum volume of approximately 80-150% of the engine displacement (V_p \approx 0.8 V_d to $1.5 V_d), depending on the design goals for RPM range and airflow distribution, ensuring sufficient air buffering to fill cylinders without excessive backpressure during intake strokes.^[17] This design enhances volumetric efficiency, potentially increasing torque by 5-10% in tuned systems compared to untuned ones, though actual gains depend on engine specifics and operating conditions. Tuned runners can further boost peak power by leveraging Helmholtz resonance, aligning pressure waves to ram additional air into cylinders at target RPMs. Common issues with air intake manifolds include vacuum leaks, often from cracked gaskets or loose connections, which disrupt pressure balance and cause uneven cylinder filling, leading to rough idling, misfires, or reduced power. In modern gasoline direct injection (GDI) systems, carbon buildup on intake valves—exacerbated by the absence of fuel washing over them—can restrict airflow, necessitating periodic cleaning or advanced designs like port injection hybrids to mitigate deposits. These problems, if unaddressed, can degrade fuel economy and increase emissions. The evolution of intake manifolds reflects advancements in materials and manufacturing. Early designs from the 1920s, such as those in Ford Model A engines, were typically cast iron for durability and heat retention to aid fuel vaporization in carbureted setups. By the 1990s, the adoption of plastic composites like nylon or glass-filled polymers became widespread, offering weight reductions of up to 50% compared to metal, lower costs, and better thermal insulation to maintain cooler intake air charges for density gains. This material shift, driven by emissions regulations and efficiency demands, has persisted into contemporary engines, with integrated sensors and active thermal management further enhancing performance.

Induction Systems

Induction systems in automotive engines are responsible for drawing air into the combustion chamber, either through natural aspiration or forced induction methods, to support the engine's power output and efficiency. Natural aspiration relies on the vacuum created by the downward motion of pistons during the intake stroke to pull air into the cylinders, limited by atmospheric pressure, which is approximately 14.7 psi at sea level. This approach is simple and cost-effective but restricts engine performance at higher altitudes or under demanding conditions due to the fixed pressure ceiling. Forced induction technologies overcome these limitations by compressing intake air to increase its density and oxygen content, allowing for greater fuel combustion and higher power from the same displacement. Turbochargers, which are exhaust-driven compressors, were pioneered in automotive applications by Garrett AiResearch with designs introduced in 1962, harnessing waste exhaust energy to spin a turbine that drives the compressor. In contrast, superchargers are mechanically driven by the engine's crankshaft via belts, with Roots-type blowers dating back to the 1910s and used in early production vehicles like the 1918 Liberty aircraft engine adapted for cars. Turbochargers generally offer better fuel efficiency since they do not parasitically load the engine, while superchargers provide immediate throttle response but consume more power. Key components in forced induction systems include intercoolers, which cool the compressed air to further increase its density and prevent detonation, and wastegates, which regulate boost pressure by diverting excess exhaust flow around the turbine. Boost pressure P_b is defined as atmospheric pressure P_a plus the compressor pressure rise \Delta P, typically ranging from 5-20 psi in modern applications to balance power and reliability. Aftermarket tuning often involves cold air intakes to source cooler, denser ambient air from outside the engine bay, enhancing volumetric efficiency, while anti-lag systems in racing maintain turbine speed during off-throttle conditions by retarding ignition or injecting fuel into the exhaust. Despite their advantages, induction systems face challenges such as heat soak in hot environments, where elevated intake temperatures reduce air density and power, and the risk of engine knock from excessive boost, which is mitigated through electronic control unit (ECU) adjustments like ignition timing retard. Historical milestones include the 1962 Oldsmobile Jetfire, the first production turbocharged car featuring a Garrett turbocharger on its 3.5L Rocket V8, and the widespread adoption of turbocharging in diesel engines by the 1980s, driven by emissions regulations and efficiency demands in vehicles like the 1981 Mercedes-Benz 300SD. These developments have made forced induction standard in high-performance and downsized engines today.

Aviation Applications

Subsonic Intakes

Subsonic intakes are designed for aircraft operating at speeds below Mach 1, where the primary goal is to efficiently capture and decelerate incoming air with minimal drag and maximal pressure recovery to supply the engine. These inlets typically feature a smooth, diverging internal geometry that diffuses the airflow, converting kinetic energy into pressure while avoiding flow separation. Podded installations, common under the wings of commercial airliners, and buried configurations within the fuselage or wing roots minimize external drag through streamlined shapes and rounded lip profiles that promote attached flow. For instance, the Boeing 737 series employs podded turbofan engine inlets with rounded lips, introduced in the 1960s, to achieve low drag during cruise at Mach 0.7–0.8.^[18]^[19] Flow conditioning within subsonic intakes relies on divergent sections to enhance pressure recovery, often incorporating features like screens or louvers to mitigate foreign object damage (FOD) from debris ingestion, particularly on rough runways. These elements ensure uniform flow distribution to the engine face, reducing distortion and maintaining efficiency across operating conditions. The performance of such intakes is quantified by the total pressure recovery coefficient, defined as \pi = \frac{P_{t2}}{P_{t1}}, where P_{t2} is the total pressure at the engine face and P_{t1} is the freestream total pressure; for subsonic operations, values exceeding 0.95 are typical to minimize losses. Applications span piston engines in general aviation and turbofan engines in commercial jets, where the intake must handle varying mass flow demands without significant spillage drag.^[20]^[21] Altitude variations affect subsonic intake performance due to decreasing air density, which can alter the inlet's capture area effectiveness and boundary layer behavior; variable geometry mechanisms, such as adjustable ramps or throats, are sometimes employed to optimize diffusion and prevent stall at high altitudes. Additionally, bleed air extracted from the engine compressor is routed through the inlet lips for thermal anti-icing, heating surfaces to evaporate supercooled droplets and prevent ice buildup during flight in icing conditions. Validation of these designs occurs through wind tunnel testing at Mach numbers up to 0.8, simulating cruise conditions to measure pressure recovery, drag, and flow uniformity under controlled Reynolds numbers and turbulence levels.^[22]^[23]

Supersonic Intakes

Supersonic intakes, also known as inlets, are critical components in high-speed aircraft propulsion systems, designed to efficiently capture and decelerate incoming air from Mach numbers exceeding 1 while managing shock waves to minimize losses in total pressure and maximize engine performance. Unlike subsonic intakes that prioritize smooth diffusion, supersonic designs focus on shockwave control to compress the airflow through a series of oblique and normal shocks, reducing the Mach number to subsonic levels before reaching the engine compressor. This process is essential for aircraft operating at Mach 1 to 3 or higher, such as fighter jets and reconnaissance planes, where improper shock positioning can lead to significant efficiency reductions or engine surge.^[20] Shock control in supersonic intakes is achieved through external compression, internal compression, or mixed configurations, each tailored to specific speed regimes and aircraft requirements. External compression inlets, such as the ramp-based designs on the McDonnell Douglas F-15 Eagle introduced in the 1970s, generate oblique shocks outside the duct using fixed or movable wedges to slow the flow with minimal boundary layer interference, achieving higher pressure recovery at moderate supersonic speeds up to Mach 2.5. In contrast, internal compression occurs entirely within the inlet duct via converging walls, but it risks stronger shock-boundary layer interactions; mixed compression, as employed in the Lockheed SR-71 Blackbird's inlets, combines external oblique shocks with internal normal shocks for optimized performance at sustained Mach 3+ cruise, balancing compression efficiency and stability.^[24]^[25]^[26] To adapt across varying flight conditions, many supersonic intakes incorporate variable geometry features, including movable ramps, cones, or spikes that adjust shock positions for Mach numbers from 1 to 3 or beyond, along with bypass doors to divert excess airflow during subsonic transitions or off-design points. For instance, the F-15's intake ramps pivot via hydraulic actuators controlled by the central air data computer, optimizing shock angles based on speed, altitude, and angle of attack to maintain stable engine operation. Similarly, the SR-71's axisymmetric spike translates forward and aft to position the terminal normal shock, while the Concorde's rectangular intakes use adjustable ramps and auxiliary doors for efficient supersonic cruise at Mach 2. The bypass mechanisms, such as spill doors, prevent spillage drag by redirecting supercritical flow around the inlet, ensuring the captured airflow matches engine demand.^[27]^[28]^[29] Performance in supersonic intakes is evaluated primarily through total pressure recovery, which quantifies energy preservation across shocks, and additive drag from spillage, where excess air spills over the lip, increasing external drag coefficients by up to 0.05-0.1 at off-design conditions. Without optimization, total pressure recovery can degrade to 0.2-0.4 at Mach 2 due to cumulative shock losses, compared to near 1.0 in subsonic diffusion; optimized multi-ramp designs achieve 0.6-0.8 by using weaker oblique shocks iteratively. The recovery across an initial normal shock, as a baseline for terminal shock analysis, is calculated using normal shock relations:

\frac{P_{t2}}{P_{t1}} = \left[ \frac{(\gamma + 1) M_1^2}{(\gamma - 1) M_1^2 + 2} \right]^{\gamma / (\gamma - 1)} \left[ \frac{\gamma + 1}{2 \gamma M_1^2 - (\gamma - 1)} \right]^{1 / (\gamma - 1)}

where \gamma is the specific heat ratio (typically 1.4 for air) and M_1 is the upstream Mach number; full inlet recovery requires chaining this with oblique shock relations for multi-shock systems. For example, at M_1 = 2, recovery drops to approximately 0.721, highlighting the need for oblique pre-compression to approach 0.85 overall. Spillage drag, arising from mismatched capture area, adds 10-20% to total aircraft drag at low mass flow ratios below 0.8.^[30]^[31]^[32] Key challenges in supersonic intake design include buzz instability during startup or unstart events, where shock oscillations at frequencies of 10-100 Hz cause pressure fluctuations up to 50% of dynamic pressure, potentially leading to engine surge or structural fatigue. Buzz arises from unsteady shock-boundary layer interactions or acoustic feedback in the duct, mitigated by bleed slots or porous walls to stabilize the shear layer. Additionally, extreme thermal loads from shock heating—reaching 800-1200°F at Mach 3—necessitate heat-resistant materials like titanium alloys, as in the SR-71, where inlet spikes and cowls were fabricated from titanium to withstand aerodynamic heating without ablation.^[33]^[34]^[26] The historical development of supersonic intakes traces back to Axis powers' World War II research on ramjet and early jet propulsion, laying groundwork for oblique shock theory. Post-war, Cold War advancements refined these concepts in U.S. and Soviet programs, culminating in operational jets like the F-15 (1976) with external ramps and the SR-71 (1966) with mixed compression. The Anglo-French Concorde, first flown in 1969, integrated variable ramp intakes for civilian supersonic transport, achieving Mach 2 cruise with 0.75 pressure recovery through refined shock management.^[31]

Industrial and Other Applications

Marine Engine Intakes

Marine engine intakes are specifically engineered to operate in harsh maritime environments, where exposure to saltwater, high humidity, and wave action poses unique challenges compared to land-based systems. These intakes must supply clean, dense air to the engine while preventing water ingress, corrosion from salt particulates, and contamination that could impair combustion efficiency or cause mechanical failure. Key adaptations include elevated air inlets, robust filtration, and integration with cooling systems that leverage seawater without compromising engine integrity.^[35]^[36] Seawater integration in marine exhaust systems, which interfaces with intake designs, employs wet exhaust configurations to mix cooling water with exhaust gases, reducing temperatures and noise. Gooseneck risers, typically stainless steel or composite, elevate the exhaust outlet above the waterline to prevent siphoning or backflow of seawater into the engine when it is idle or in reverse, a critical safeguard against hydrolock.^[37]^[38] Flame arrestors, mandatory on gasoline-powered marine engines since 1940 per U.S. Coast Guard regulations, are installed in the intake path to quench backfires and prevent ignition of fuel vapors, enhancing safety by dispersing flames away from the vessel.^[39]^[40] These components ensure reliable operation in wet conditions without allowing corrosive seawater to enter the combustion chamber. Air sourcing for marine engines relies on above-waterline scoops, snorkels, or vented grilles positioned high on the hull or superstructure to draw in ambient air while avoiding sea spray and waves. In rough seas, downflooding prevention is achieved through elevated intake heights—often exceeding the vessel's static waterline by at least 0.5 meters—and mist eliminators or vane separators that trap moisture and salt-laden droplets, directing them to drain while allowing dry air to pass.^[41]^[42] This design minimizes the risk of water ingestion during heeling or pitching, as seen in stormy conditions where waves could otherwise flood lower intakes.^[43]^[44] Diesel engines, predominant in marine propulsion, feature oversized air filters to capture salt particulates prevalent in coastal and offshore air, with airborne salt concentrations reaching up to 30,000 particles per cubic foot even far from shore. These filters, often reusable foam or rigid elements, protect turbochargers and cylinders from abrasive wear and corrosion. Turbochargers commonly incorporate seawater-cooled aftercoolers, which use raw seawater to chill compressed intake air, increasing its density by up to 20% and boosting power output while mitigating thermal stress in humid environments.^[45]^[46]^[47]^[48]^[49] Performance in marine settings requires adjustments for high humidity, which reduces effective air density and volumetric efficiency. The effective density \rho_{eff} accounts for water vapor displacement of oxygen using the formula:

\rho_{eff} = \rho_{dry} \left(1 - 0.378 \frac{P_v}{P - P_v}\right)

where \rho_{dry} is dry air density, P_v is water vapor pressure, and P is total atmospheric pressure; this correction can lower density by 5-10% in tropical conditions, necessitating tuned intake lengths or intercooling to maintain power.^[50] International Maritime Organization (IMO) standards under MARPOL Annex VI, effective from 2000 with Tier I NOx limits (e.g., 17.0 g/kWh for low-speed engines), have driven intake optimizations for cleaner combustion, including high-quality air filtration to reduce particulates and support low-emission technologies like exhaust gas recirculation. Subsequent tiers (II in 2011, III in 2016 for ECAs) further influence designs by promoting water injection into intake air to lower NOx formation. Amendments adopted in 2025 to MARPOL Annex VI and the NOx Technical Code, effective from 2028, introduce multiple engine operational profiles (MEOP) to enhance compliance flexibility, further influencing intake system designs for emission controls.^[51]^[52]^[53] Examples illustrate these adaptations: Outboard motors, such as Yamaha's F70-F200 series, use pulse-tuned long intake manifolds—durable plastic tracts that leverage pressure waves for precise air delivery, enhancing torque at low RPMs without spray intrusion. In contrast, inboard marine diesels often employ silencer-based intakes with no housing for minimal restriction or washable foam filters for easy maintenance in saltwater, prioritizing volume over fine filtration in larger vessels.^[54]^[55]^[56]

Gas Turbine Intakes

Gas turbine intakes for industrial applications serve to deliver clean, conditioned ambient air to the compressor inlet, ensuring optimal engine performance while mitigating environmental contaminants and weather-related risks. These systems are critical in stationary power generation, where they must handle high airflow rates—such as 587 kg/s for a GE MS9001F unit—while minimizing pressure losses that can reduce output by up to 0.5% per 1 inH₂O of additional drop.^[57]^[58] Design principles emphasize uniform velocity distribution, achieved through computational fluid dynamics (CFD) modeling, and elevation of intake housings to at least 20 feet to halve ground-level dust ingestion.^[57]^[58] Key components include weather hoods, inertial separators, multi-stage filtration banks, and ducting, often integrated into filter houses for compactness in space-constrained sites like offshore platforms. Inertial separators remove up to 99% of particles larger than 10 microns, while weather hoods limit inlet velocity to 650 ft/min (3.3 m/s) to prevent rain ingress.^[58] Filtration systems typically feature two to three stages: coarse prefilters (e.g., MERV 8-11 per ASHRAE 52.2) for larger debris, followed by high-efficiency filters (e.g., E10-E12 per EN 1822) that reduce dust loading to as low as 1 kg/year in controlled environments.^[59]^[58] Self-cleaning pulse-jet mechanisms, used in 80-90% of modern installations, extend filter life to about two years in dusty regions like the Middle East by automatically removing accumulated particulates.^[57] Industrial gas turbines face challenges from site-specific contaminants, such as desert sand (up to hundreds of ppm during storms) causing erosion on particles over 20 microns, or coastal salt aerosols leading to hot corrosion and fouling that can diminish power output by 10-15%.^[57]^[59] High humidity in offshore settings exacerbates liquid carryover, increasing pressure drops to 750-1000 Pa, while low temperatures below -22°F (-30°C) risk icing that blocks airflow.^[59] Solutions incorporate evaporative coolers achieving 85% effectiveness to lower inlet temperatures by 21°F (12°C) at 100°F (38°C) ambient, boosting output, and anti-icing via compressor bleed air heated to 500-750°F (260-400°C).^[57] For corrosive environments, hydrophobic E12 filters and stainless steel construction minimize salt ingress to 0.0000018 ppbw, extending maintenance intervals from 4 weeks to 6 months.^[59] Performance optimization relies on life-cycle cost analysis, comparing systems like prefilter-only setups (0.5-1.5 inH₂O loss, 5% annual power degradation) against two-stage high-efficiency configurations (2-4 inH₂O loss but only 1.5% degradation and net 1.5% power gain despite added drop).^[58] In offshore applications, low-velocity designs (2.5-3.5 m/s) prioritize E12 filtration for reliability, weighing 24,500 kg but reducing unplanned downtime through fewer washes (every 8760 hours versus 4380).^[59] Overall, effective intake systems enhance availability to 85% (7446 hours/year) and cut operational expenses by up to $1.6 million over 15 years via reduced fouling and maintenance.^[58]

References

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https://www.merriam-webster.com/dictionary/intake
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INTAKE | definition in the Cambridge English Dictionary
the amount of something such as food, breath, or a liquid that is taken in by someone or something: the intake of fuel in a vehicle, a deep intake of breath.
[3]
INTAKE definition in American English - Collins Dictionary
An intake is an opening through which fluid enters a duct or channel, usually the air inlet of an engine. It is important to ensure that solid objects do not ...
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intake noun - Definition, pictures, pronunciation and usage notes
intake · . [uncountable, countable] the amount of food, drink, etc. · . [countable + singular or plural verb, uncountable] the people who are allowed to enter ...
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An intake system is defined as a structure designed to protect against environmental elements such as snow and rain, while facilitating airflow.
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What are Intake Structures? 8 Types of Intake Structures
Intake structures collect water from surface sources like rivers and convey it to treatment plants. They are masonry or concrete structures.
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the place or opening at which a fluid is taken into a channel, pipe, etc. an act or instance of taking in. an intake of oxygen. something that is taken in.
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[PDF] summary of subsonic -d - NASA Technical Reports Server (NTRS)
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Concorde air intakes
The air in-take is rectangular in cross section and is of variable geometry in that it embodies two moving ramps in the top surface.
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[PDF] a variable-geometry axisymmetric supersonic inlet with telescoping ...
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[36]
Normal Shock Wave Equations
M1^2 = [(gam - 1) * M^2 + 2] / [2 * gam * M^2 - (gam - 1)] · Tt1 / Tt0 = 1 · T1 / T0 = [2 * gam * M^2 - (gam - 1)] * [(gam - 1) * M^2 + 2] / [(gam + 1)^2 * M^2].
[37]
[PDF] Supersonic Inlets - DTIC
Greater flexibility of operation is achieved if the compres¬ sion through the oblique shock takes place externally. The shock attached to the tip of a central ...
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[PDF] Design and Analysis Tool for External-Compression Supersonic Inlets
Jan 8, 2012 · The inlets incorporated a throat slot at the end of the external diffuser ramps to reduce the adverse effects of shock/ boundary layer ...Missing: principles | Show results with:principles
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[PDF] Analysis of Buzz in a Supersonic Inlet
Buzz in a supersonic inlet occurs at mass flows below engine operation, and the buzz cycle consists partly of spike buzz, an unsteady oscillation.Missing: challenges thermal
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External-Compression Supersonic Inlet Free from Violent Buzz
It is designed to have plenty of narrow flush slots that are widely distributed along the compression surface.
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Engine Room Air Intake Grilles - Marine Air Flow
Engine room air intake grilles stop salt mist by using vanes to trap moisture, drawing it out of the air and preventing damage.Missing: scoops snorkels
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The Simple Truth About Marine Engine Maintenance
Jun 8, 2015 · In their quenchless drive for combustion air, big diesels will pull in salt water along with salt air unless the boat has proper baffles, or ...
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Marine Exhaust Risers: Purpose, Design, and Maintenance Guide
Preventing Water Ingress: A well designed riser prevents cooling water ... prevent water from siphoning back into the exhaust system when the engine is off.
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Installing a Wet Exhaust Gooseneck - SV Ramble On
The wet exhaust gooseneck is designed to prevent seawater from backflowing into your engine. Especially when your exhaust outlet sits close to or below the ...
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Backfire Flame Arrestors - Boat Ed
Backfire flame arrestors prevent gasoline vapor ignition during engine backfires, dispersing flames outside the vessel, and are required on powerboats (except ...
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Marine Safety: A Guide to Flame Arrestors for Vessel Protection
May 12, 2025 · Flame arrestors are crucial for safety in marine applications. They prevent the spread of fire, protect personnel and equipment, ...
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Intake Grille Demo - Marine Air Flow
Nov 27, 2018 · See how our mist eliminator (or intake grilles) work with this video demo showcasing how effective our grilles are at keeping out salt mist and spray.<|separator|>
[48]
Engine air intake snorkel above the PH? - Trawler Forum
Nov 8, 2019 · The snorkels I see are like a J with the opening facing down and provide the engine with fresh air directly into the air filter element. I'm ...
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Examining Ship Engine Failures on Stormy Seas
Mar 25, 2019 · Would there be a future need for air/water separators to prevent seawater from reaching the engine intake manifolds? Or could the occurrence be ...Missing: rough | Show results with:rough
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[PDF] SAFETY GUIDE -Final to press.cdr - FAO Knowledge Repository
To prevent waves from flooding into the boat in rough weather and with a full load, the downflooding height must be sufficient to prevent the boat from being ...
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Marine diesel air filters, or the lack thereof. - Sailboat Owners Forums
Nov 20, 2012 · Even far out at sea, airborne particulate are and remain in the range of 30,000 particles per cu. ft.
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https://www.imo.org/en/OurWork/Environment/Pages/Index-of-MEPC-Resolutions-and-Guidelines-related-to-MARPOL-Annex-VI.aspx
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https://www.dnv.com/news/2025/imo-mepc-83-ghg-requirements-approved-taking-effect-from-2028/
[54]
https://global.yamaha-motor.com/business/outboards/products/4st/l4-200-115/
[55]
https://yamahaoutboards.com/outboards/115-30-hp/70-50-hp
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Equations - Air Density and Density Altitude - Wahiduddin's Web
Jan 21, 2023 · To find the actual vapor pressure, simply multiply the saturation vapor pressure by the percentage and the result is the actual vapor pressure.Missing: effective | Show results with:effective
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IMO Marine Engine Regulations - Emission Standards - DieselNet
Overview of emission and fuel requirements for marine engines under the IMO MARPOL Annex VI convention.Missing: intake | Show results with:intake
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L4 200-115ps - Outboards | Yamaha Motor Co., Ltd.
The VCT, which advances and retards the camshaft timing according to the engine rpm, the electronically controlled single throttle system and a pulse tuned long ...
[59]
70-50 HP 1L Midrange Outboard Motors
It then enters each cylinder through individual long intake tracks, which are 'pulse tuned' to provide air at the precise volume and timing for maximum density ...
[60]
5 Types of Diesel Engine Air Intakes - MARINE DIESEL BASICS
The five types are: replaceable paper filter, reusable rigid filter, washable foam filter, intake silencer, and air intake with no filter or housing.Missing: inboard | Show results with:inboard
[61]
[PDF] GER-3419A - Gas Turbine Inlet Air Treatment - GE Vernova
Inlet systems for cold climates are designed to protect the gas turbine from damage due to icing and to keep the machine running with minimum effect on ...
[62]
[PDF] Guideline for Gas Turbine Inlet Air Filtration Systems
The selection of the inlet filtration system is an important part of the design of a gas turbine. Poor quality inlet air can significantly impact the operation, ...<|control11|><|separator|>
[63]
[PDF] Gas Turbine Air Filtration Systems For Offshore Applications
All Gas Turbine (GT) inlet filters are designed to deal with the common types of contaminants such as; sand, dust and soot. Operation in the marine environment ...