Dear experts: How to determine the negative pressure generated by the jet at the nozzle outlet?

Bernoulli's equation can be used, the original outlet pressure = the negative pressure of the flowing mixed gas + the flow rate of the mixed gas. Note that the mixed gas flow rate is not the exit velocity of the nozzle. The flow rate of the mixed gas can be deduced from the nozzle outlet flow rate and the mixing ratio.

Thank you for the help on the 2nd floor! But it feels wrong, at least the unit is wrong. Flow rate and pressure obviously have different units.

The first floor talks about energy balance, which can be slightly modified.: The static pressure energy of the original outlet pressure = the static pressure energy of the negative pressure of the flowing mixed gas + the kinetic energy generated by the flow rate of the mixed gas. P1=P2+U2 * U2/(2pg)

It’s not solved yet! If "The second floor is right", I will assume that the flow rate of the mixed gas is 60m/s, and the original outlet pressure is 60KPa. What is the negative pressure at the nozzle outlet?

Thank you also for the help on the 4th floor! There is nothing wrong with using the principle of energy conservation. However, "static pressure energy" has a parameter called volume, and this parameter cannot be determined at all. There is a pipe in front of the nozzle. The actual pipe can be long or short (that is, the volume is variable). It will not affect the negative pressure at the nozzle outlet at all, and the atmosphere comes out of the nozzle. How to determine the volume?

The pressure calculated directly using Bernoulli's equation is incorrect. Simply when the flow rate reaches a certain level, a pressure lower than absolute vacuum will be obtained. This is impossible because there is a loss of mechanical energy in the mixing process.

Please refer to the approximate equation of the jet pump. At the same time, it is related to the structure of the pump jet, such as the nozzle flow coefficient. The relevant working pressure drop is calculated according to the equation, and the working inlet pressure can be calculated. Since it is related to the structure, the parameters mentioned by the poster are not complete, so I can only provide you with the method to solve the problem. For example, the flow coefficient, etc., may be provided by the manufacturer. There are other parameters that need to be further implemented. It is recommended that the poster download the relevant design manual, and you need to read the manual. The design manual is indispensable, and there may be other problems in the future. The manual can be found in the forum. If the wealth is not enough, it is recommended to visit often and get some wealth from the forum. This post was last edited by Albertlu on 2009-1-29 11:53 ]

Now that I have received extra points, there is no need to say more words of thanks. It should be obvious from the main post that I had done some work before seeking help, and consulted some chemical engineering manuals and encyclopedias. However, I did not give an ideal answer before posting, asking for a "concrete" answer. You're obviously not specific enough, and I don't have the "Petrochemical Engineering Design Manual" either, so the problem still hasn't been solved! Please don't be offended! It's not that I deliberately embarrass others, but I'm afraid that the moderator will think that the problem has been solved and change "help" to "resolved". Then I won't get a "specific" answer, so I just talked nonsense.

I have explained my previous reply, please refer to it.