![]() RE: Manifold design davefitz (Mechanical) 12 Jun 13 07:23Īm I missing the point entirely here? This seems like a trivially easy problem. Independent events are seldomly independent. A 10 psig manifold pressure would have around a +/- 25% rate of equality. That should produce outflows that vary by no more than +/- 15%. The square root of the difference between all manifold outlet differential pressures in a 7 foot length, even if vertical and immersed in water (3 psi) will not make a hill of beans difference to the flow across each orifice, as long as the pressure inside the manifold is somewhat high relative to the 3 psi, all flows will be nearly the same, high being only 20 psi. What controls the flow from a short manifold is the resistance to flow through each outlet, which is primarily controlled by the square root of the differential pressure across each outlet, Q = K dH^2. It's not going to happen in a short 7 ft long manifold. Frictional resistance between outlets must be much more than the pressure increase due to slowing flow in order to get any difference in outflow between similar outlets. Considering static pressure increase as velocity slows as fluid is removed at one outlet and less and less fluid moves to the next outlet, static pressures actually increase in the downstream direction within the manifold, except for those extremely long manifolds where the distances between outlets are so far apart the friction from flow between outlet to outlet begins to amount to something, or fluid is extremely viscous and friction loss/unit length is very high. Outflow from each will be almost the same. The plural of anecdote is not "data" RE: Manifold design cvg (Civil/Environmental) 11 Jun 13 19:52ĭrill equal holes at equal spacing. "Knowledge" is only found through the accumulation and analysis of data. "Prejudice" is having an opinion not supported by the preponderance of the data. "Belief" is the acceptance of an hypotheses in the absence of data. You could do equal hole sizes if you could turn your manifold horizontal, but you would still get more flow from the hole(s) closest to the source. If the manifold just has to be vertical, then I would enter it from the bottom and gradate the hole size (so that the first hole the water sees is the smallest hole at the highest pressure, and so forth until the top is the biggest hole at the lowest pressure). You could try to fake it by making the upper holes slightly larger, but that would give you some pretty unstable fluid dynamics. ![]() The pressure at the lowest hole is significantly higher than the pressure in the highest hole due to hydrostatic gradient. If you are looking for "kind of" uniform then it is possible, but not in your configuration. A microbar difference in resistance can completely change the flow. This can be seen in the attached diagram.First, flow is never uniform no matter what you do. Because of its position it should always read a negative pressure unless the turboĬharger is boosting pressure. The Manifold Pressure Sensor can be used for diagnostics as it measures the throttle performance, turbo performance and can be used to detect leaks in the inlet manifold. A fuel-injected engine may use a MAF sensor or a Pressure sensor- or sometimes even both. Is used to calculate air density and determine the engine's air mass flow rate, which in turn determines the required fuel delivery for perfect combustion. The sensor provides instant manifold pressure information to the engine's electronic control unit. Engines that use a pressure sensor are typically fuel injected. The Manifold Pressure Sensor is used in an engine's electronic control system.
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