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48-598: [REDACTED] Look up choke in Wiktionary, the free dictionary. Not to be confused with Choking . Choke may refer to: Entertainment [ edit ] Albums and songs [ edit ] Choke (album) , a 1990 album by the Beautiful South "Choke" (I Dont Know How But They Found Me song) , a 2017 song from the album 1981 Extended Play Choke (Kiss It Goodbye EP) , 1999 "Choke" (Sepultura song) , from

96-1034: A x {\displaystyle c_{s}^{*}={\sqrt {\gamma {\frac {p}{\rho ^{*}}}}}={\sqrt {{\frac {2}{\mu }}C_{P}T}}=v_{max}} , where ρ ∗ {\displaystyle \rho ^{*}} is the density at the critical cross-section. We can now obtain the pressure p {\displaystyle p} as: p = ρ ∗ c s ∗ 2 γ = m ˙ A ∗ c s ∗ γ {\displaystyle p={\frac {\rho ^{*}{c_{s}^{*}}^{2}}{\gamma }}={\frac {\dot {m}}{A^{*}}}{\frac {c_{s}^{*}}{\gamma }}} , taking in account that ρ ∗ c s ∗ A ∗ = m ˙ {\displaystyle \rho ^{*}c_{s}^{*}\,A^{*}={\dot {m}}} . Now remember that we have neglected gas velocity upstream, that

144-494: A 2001 song from the album Echo Park by Feeder "Choke", a 2006 song from the album I Choose Noise by Hybrid "Choke", a 2007 song from the album Aneurythm by Living Syndication "Choke", a 2009 song from the album Sorry for Partyin' by Bowling for Soup "Choke", a 2013 song from the album The Devil Put Dinosaurs Here by Alice in Chains "Choke", a 2016 song from the album Oh My My by OneRepublic "Choke",

192-455: A 2009 song from the album Sorry for Partyin' by Bowling for Soup "Choke", a 2013 song from the album The Devil Put Dinosaurs Here by Alice in Chains "Choke", a 2016 song from the album Oh My My by OneRepublic "Choke", a 2021 song by the Warning "Choke", a 2022 song from the album True Power by I Prevail Film and television [ edit ] Choke (2008 film) ,

240-413: A 2021 song by the Warning "Choke", a 2022 song from the album True Power by I Prevail Film and television [ edit ] Choke (2008 film) , a film based on the novel by Chuck Palahniuk Choke (2011 film) , a Canadian animated short film Choke (1999 film) , a documentary about Rickson Gracie 's preparation for the 1995 Vale Tudo Fighting Championship Choke (2001 film) ,

288-410: A Canadian band Choke (novel) , a 2001 novel by Chuck Palahniuk Choke , a 1995 novel by Stuart Woods Other uses [ edit ] Choke (electronics) , an inductor used to block signals of particular frequencies An inductor of any type, sometimes referred to as a choke Choke (firearms) , a tapered constriction of a shotgun barrel's bore at the muzzle end Choke (horse) ,

336-408: A choke Choke (firearms) , a tapered constriction of a shotgun barrel's bore at the muzzle end Choke (horse) , a condition in horses in which the esophagus is blocked Choke (sports) , a failure to win games at a crucial moment Choking , obstruction of airflow into the lungs Chokehold , a grappling hold on the neck Choked flow , a restriction of fluid flow under pressure, in which

384-403: A condition in horses in which the esophagus is blocked Choke (sports) , a failure to win games at a crucial moment Choking , obstruction of airflow into the lungs Chokehold , a grappling hold on the neck Choked flow , a restriction of fluid flow under pressure, in which the fluid reaches sonic flow Choke point , a constriction in a conduit or transport system, e.g. a narrowing of

432-490: A film based on the novel by Chuck Palahniuk Choke (2011 film) , a Canadian animated short film Choke (1999 film) , a documentary about Rickson Gracie 's preparation for the 1995 Vale Tudo Fighting Championship Choke (2001 film) , a psychological thriller directed by John M. Sjogren Choked (film) , a 2020 Indian drama film "Choke" ( Glee ) , an episode of Glee Choke. , 2004 Canadian film Other entertainment [ edit ] Choke (band) ,

480-433: A further decrease in the downstream pressure environment for a fixed upstream pressure and temperature. For homogeneous fluids, the physical point at which the choking occurs for adiabatic conditions is when the exit plane velocity is at sonic conditions; i.e., at a Mach number of 1. At choked flow, the mass flow rate can be increased only by increasing the upstream density of the substance. The choked flow of gases

528-425: A mixture of subsonic and supersonic flow, or (if the back pressure is low enough) just supersonic flow. Because the shock is no longer perpendicular to the flow near the nozzle walls, it deflects the flow inward as it leaves the exit producing an initially contracting jet. This is referred as overexpanded flow because in this case the pressure at the nozzle exit is lower than that in the ambient (the back pressure)- i.e.

SECTION 10

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576-404: A near-instantaneous deceleration of the flow to subsonic speed. This subsonic flow then decelerates through the remainder of the diverging section and exhausts as a subsonic jet. In this regime if you lower or raise the back pressure you move the shock wave away from (increase the length of supersonic flow in the diverging section before the shock wave) the throat. If the p b is lowered enough,

624-532: A psychological thriller directed by John M. Sjogren Choked (film) , a 2020 Indian drama film "Choke" ( Glee ) , an episode of Glee Choke. , 2004 Canadian film Other entertainment [ edit ] Choke (band) , a Canadian band Choke (novel) , a 2001 novel by Chuck Palahniuk Choke , a 1995 novel by Stuart Woods Other uses [ edit ] Choke (electronics) , an inductor used to block signals of particular frequencies An inductor of any type, sometimes referred to as

672-454: A road Choke valve , a valve used to control the fuel-air mixture in internal combustion engines Chokecherry , a suckering shrub or small tree, a species of bird cherry Choke Yasuoka (born 1973), wheelchair racer See also [ edit ] Chowk (disambiguation) (pronounced "choke"), in Hindi-Urdu, is a place where paths intersect Artichoke (or 'chokes), vegetable using

720-650: A specific individual gas. The relationship between the two constants is R s = R / M where M is the molecular weight of the gas. If the upstream conditions are such that the gas cannot be treated as ideal, there is no closed form equation for evaluating the choked mass flow. Instead, the gas expansion should be calculated by reference to real gas property tables, where the expansion takes place at constant enthalpy. The minimum pressure ratios required for choked conditions to occur (when some typical industrial gases are flowing) are presented in Table 1. The ratios were obtained using

768-566: Is a place where paths intersect Artichoke (or 'chokes), vegetable using the flower head Sunchoke , vegetable using the tuber Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Choke . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Choke&oldid=1254946242 " Category : Disambiguation pages Hidden categories: Short description

816-404: Is different from Wikidata All article disambiguation pages All disambiguation pages choke [REDACTED] Look up choke in Wiktionary, the free dictionary. Not to be confused with Choking . Choke may refer to: Entertainment [ edit ] Albums and songs [ edit ] Choke (album) , a 1990 album by

864-456: Is different from Wikidata All article disambiguation pages All disambiguation pages Choked flow Choked flow is a fluid dynamic condition associated with the Venturi effect . When a flowing fluid at a given pressure and temperature passes through a constriction (such as the throat of a convergent-divergent nozzle or a valve in a pipe ) into a lower pressure environment

912-675: Is pressure at the critical section must be essentially the same or close to the stagnation pressure upstream P 0 ≈ p {\displaystyle P_{0}\approx p} , and A ∗ ≈ A {\displaystyle A^{*}\approx A} . Finally we obtain: m ˙ = γ P 0 A ( 2 μ C P T 0 ) − 1 / 2 {\displaystyle {\dot {m}}=\gamma \,P_{0}\,A\,\left({\frac {2}{\mu }}C_{P}\,T_{0}\right)^{-1/2}} as an approximate equation for

960-401: Is referred to as the 'design condition'. Finally, lowering the back-pressure even further creates a new imbalance between the exit and back pressures (exit pressure greater than back pressure), figure 1g. In this situation (called 'underexpanded') expansion waves (that produce gradual turning perpendicular to the axial flow and acceleration in the jet) form at the nozzle exit, initially turning

1008-436: Is the specific heat ratio of the gas. The minimum pressure ratio may be understood as the ratio between the upstream pressure and the pressure at the nozzle throat when the gas is traveling at Mach 1; if the upstream pressure is too low compared to the downstream pressure, sonic flow cannot occur at the throat. Notes: The flow through a venturi nozzle achieves a much lower nozzle pressure than downstream pressure. Therefore,

SECTION 20

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1056-444: Is the enthalpy of gas, C P = γ γ − 1 R {\displaystyle C_{P}={\frac {\gamma }{\gamma -1}}R} - molar specific heat at constant pressure, with R {\displaystyle R} being the universal gas constant, T {\displaystyle T} - absolute temperature. If we neglect the initial gas velocity upstream, we can obtain

1104-455: Is useful in many engineering applications because the mass flow rate is independent of the downstream pressure, and depends only on the temperature and pressure and hence the density of the gas on the upstream side of the restriction. Under choked conditions, valves and calibrated orifice plates can be used to produce a desired mass flow rate. If the fluid is a liquid, a different type of limiting condition (also known as choked flow) occurs when

1152-481: The venturi effect acting on the liquid flow through the restriction causes a decrease of the liquid pressure beyond the restriction to below that of the liquid's vapor pressure at the prevailing liquid temperature. At that point, the liquid partially flashes into bubbles of vapor and the subsequent collapse of the bubbles causes cavitation . Cavitation is quite noisy and can be sufficiently violent to physically damage valves, pipes and associated equipment. In effect,

1200-525: The Beautiful South "Choke" (I Dont Know How But They Found Me song) , a 2017 song from the album 1981 Extended Play Choke (Kiss It Goodbye EP) , 1999 "Choke" (Sepultura song) , from the album Against , 1998 Choke , a 2019 EP by Poppy "Choke", a 1996 song from the album First Band on the Moon by the Cardigans "Choke", a 1997 song from the album Double Plaidinum by Lagwagon "Choke",

1248-546: The absolute pressure in stagnant upstream source vessel. When the gas velocity is choked, one can obtain the mass flowrate as a function of the upstream pressure. For isentropic flow Bernoulli's equation should hold: h + v 2 2 = C P T μ + v 2 2 = c o n s t {\displaystyle h+{\frac {v^{2}}{2}}={\frac {C_{P}T}{\mu }}+{\frac {v^{2}}{2}}=const} , where h {\displaystyle h} -

1296-433: The album Against , 1998 Choke , a 2019 EP by Poppy "Choke", a 1996 song from the album First Band on the Moon by the Cardigans "Choke", a 1997 song from the album Double Plaidinum by Lagwagon "Choke", a 2001 song from the album Echo Park by Feeder "Choke", a 2006 song from the album I Choose Noise by Hybrid "Choke", a 2007 song from the album Aneurythm by Living Syndication "Choke",

1344-414: The below expression: The above equations calculate the steady state mass flow rate for the pressure and temperature existing in the upstream pressure source. If the gas is being released from a closed high-pressure vessel, the above steady state equations may be used to approximate the initial mass flow rate. Subsequently, the mass flow rate decreases during the discharge as the source vessel empties and

1392-414: The criterion that choked flow occurs when the ratio of the absolute upstream pressure to the absolute downstream pressure is equal to or greater than ( [ γ + 1 ] / 2 ) γ / ( γ − 1 ) {\displaystyle ([\gamma +1]/2)^{\gamma /(\gamma -1)}} , where γ {\displaystyle \gamma }

1440-473: The downstream pressure at all. All other terms are constants that depend only on the composition of the material in the flow. Although the gas velocity reaches a maximum and becomes choked, the mass flow rate is not choked . The mass flow rate can still be increased if the upstream pressure is increased as this increases the density of the gas entering the orifice. The value of C d {\displaystyle C_{d}} can be calculated using

1488-415: The downstream pressure falls below a critical value p ∗ {\displaystyle p^{*}} . That critical value can be calculated from the dimensionless critical pressure ratio equation where γ {\displaystyle \gamma } is the heat capacity ratio c p / c v {\displaystyle c_{p}/c_{v}} of

Choke - Misplaced Pages Continue

1536-416: The downstream pressure is reduced below the critical pressure. Cunningham (1951) first drew attention to the fact that choked flow does not occur across a standard, thin, square-edged orifice. In the case of upstream air pressure at atmospheric pressure and vacuum conditions downstream of an orifice, both the air velocity and the mass flow rate become choked or limited when sonic velocity is reached through

1584-406: The flow has been expanded by the nozzle too much. A further lowering of the back pressure changes and weakens the wave pattern in the jet. Eventually the back pressure becomes low enough so that it is now equal to the pressure at the nozzle exit. In this case, the waves in the jet disappear altogether (figure 1f), and the jet becomes uniformly supersonic. This situation, since it is often desirable,

1632-416: The flow pattern in the diverging section does change as you lower the back pressure further. As p b is lowered below that needed to just choke the flow, a region of supersonic flow forms just downstream of the throat. Unlike in subsonic flow, the supersonic flow accelerates as it moves away from the throat. This region of supersonic acceleration is terminated by a normal shock wave. The shock wave produces

1680-418: The flow speed everywhere in the nozzle. When the back pressure, p b , is lowered enough, the flow speed is Mach 1 at the throat, as in figure 1b. The flow pattern is exactly the same as in subsonic flow, except that the flow speed at the throat has just reached Mach 1. Flow through the nozzle is now choked since further reductions in the back pressure can't move the point of M=1 away from the throat. However,

1728-488: The flower head Sunchoke , vegetable using the tuber Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Choke . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Choke&oldid=1254946242 " Category : Disambiguation pages Hidden categories: Short description

1776-439: The fluid reaches sonic flow Choke point , a constriction in a conduit or transport system, e.g. a narrowing of a road Choke valve , a valve used to control the fuel-air mixture in internal combustion engines Chokecherry , a suckering shrub or small tree, a species of bird cherry Choke Yasuoka (born 1973), wheelchair racer See also [ edit ] Chowk (disambiguation) (pronounced "choke"), in Hindi-Urdu,

1824-432: The fluid velocity increases. At initially subsonic upstream conditions, the conservation of energy principle requires the fluid velocity to increase as it flows through the smaller cross-sectional area of the constriction. At the same time, the venturi effect causes the static pressure, and therefore the density, to decrease at the constriction. Choked flow is a limiting condition where the mass flow cannot increase with

1872-439: The gas and where p 0 {\displaystyle p_{0}} is the total (stagnation) upstream pressure. For air with a heat capacity ratio γ = 1.4 {\displaystyle \gamma =1.4} , then p ∗ = 0.528 p 0 {\displaystyle p^{*}=0.528p_{0}} ; other gases have γ {\displaystyle \gamma } in

1920-429: The higher upstream density. The choked velocity is a function of the upstream pressure but not the downstream. Although the velocity is constant, the mass flow rate is dependent on the density of the upstream gas, which is a function of the upstream pressure. Flow velocity reaches the speed of sound in the orifice, and it may be termed a sonic orifice . Assuming ideal gas behavior, steady-state choked flow occurs when

1968-418: The mass flowrate. The more precise equation for the choked mass flow rate is: The mass flow rate is primarily dependent on the cross-sectional area A {\displaystyle A} of the nozzle throat and the upstream pressure P {\displaystyle P} , and only weakly dependent on the temperature T {\displaystyle T} . The rate does not depend on

Choke - Misplaced Pages Continue

2016-413: The orifice. Figure 1a shows the flow through the nozzle when it is completely subsonic (i.e. the nozzle is not choked). The flow in the chamber accelerates as it converges toward the throat, where it reaches its maximum (subsonic) speed at the throat. The flow then decelerates through the diverging section and exhausts into the ambient as a subsonic jet. In this state, lowering the back pressure increases

2064-407: The pressure in the vessel decreases. Calculating the flow rate versus time since the initiation of the discharge is much more complicated, but more accurate. The technical literature can be confusing because many authors fail to explain whether they are using the universal gas law constant R, which applies to any ideal gas or whether they are using the gas law constant R s , which only applies to

2112-427: The pressure ratio is the comparison between the upstream and nozzle pressure. Therefore, flow through a venturi can reach Mach 1 with a much lower upstream to downstream ratio. The flow of real gases through thin-plate orifices never becomes fully choked. The mass flow rate through the orifice continues to increase as the downstream pressure is lowered to a perfect vacuum, though the mass flow rate increases slowly as

2160-402: The range 1.09 (e.g. butane) to 1.67 (monatomic gases), so the critical pressure ratio varies in the range 0.487 < p ∗ / p 0 < 0.587 {\displaystyle 0.487<p^{*}/p_{0}<0.587} , which means that, depending on the gas, choked flow usually occurs when the downstream static pressure drops to below 0.487 to 0.587 times

2208-413: The shock wave sits at the nozzle exit (figure 1d). Due to the long region of acceleration (the entire nozzle length) the flow speed reaches its maximum just before the shock front. However, after the shock the flow in the jet is subsonic. Lowering the back pressure further causes the shock to bend out into the jet (figure 1e), and a complex pattern of shocks and reflections is set up in the jet that create

2256-609: The ultimate gas velocity as follows: v m a x = 2 μ C P T {\displaystyle v_{max}={\sqrt {{\frac {2}{\mu }}C_{P}T}}} In a choked flow this velocity happens to coincide exactly with the sonic velocity c s ∗ {\displaystyle c_{s}^{*}} at the critical cross-section: c s ∗ = γ p ρ ∗ = 2 μ C P T = v m

2304-412: The vapor bubble formation in the restriction prevents the flow from increasing any further. All gases flow from higher pressure to lower pressure. Choked flow can occur at the change of the cross section in a de Laval nozzle or through an orifice plate . The choked velocity is observed upstream of an orifice or nozzle. The upstream volumetric flow rate is lower than the downstream condition because of

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