阅读说明：本技术 一种测量气体音速射流卷吸的质量流量方法 (method for measuring mass flow rate of gas sonic jet entrainment ) 是由 雷艳 吴悦 仇滔 李�泳 于 2019-10-31 设计创作，主要内容包括：一种测量气体音速射流卷吸的质量流量方法属于流体力学的高压气体射流质量测量领域。高压导致这种射流在喷孔出口处达到音速,气体射流出来后会不断卷吸背景气体,在射流方向上,垂直截面的运动混合气体质量不断增加。该方法是根据气体射流过程中,在出口截面和需要测量的截面动量守恒,包括五个基本步骤：实验测量射流出口端气体的质量流量；计算出口截面的当地音速；计算出口端气体的动量；实验得到射流方向上被测截面的射流速度；结合动量守恒计算该截面混合气体的质量流量并在减去出口截面质量基础上获得射流到该截面的卷吸背景气体的质量。(method for measuring the mass flow rate of gas jet entrainment includes such steps as measuring the mass flow rate of gas at outlet of jet, calculating the local sound velocity of outlet section, calculating the momentum of gas at inlet end, measuring the jet flow rate of measured section, calculating the mass flow rate of mixed gas at outlet section, and subtracting the mass of outlet section to obtain the mass of background gas.)

1, A method for measuring mass flow of gas sonic jet entrainment, comprising the steps of:

(1) measuring the mass flow of the gas at the jet flow outlet end;

(2) calculating the local sound velocity of the outlet section;

(3) calculating the momentum of gas at the opening end;

(4) obtaining the jet velocity of the measured section in the jet direction;

(5) and calculating the mass flow of the mixed gas of the section by combining momentum conservation, and obtaining the mass of entrainment background gas jetted to the section on the basis of subtracting the mass of the outlet section.

2. The method of claim 1, wherein:

(1) obtaining outlet end gas mass flow by adopting a drainage method;

(2) and measuring the jet flow penetration speed by adopting a schlieren method to obtain the high-pressure gas jet flow speed at the section.

3. The method of claim 1, wherein:

the high-pressure gas flows out through the spray holes, finite elements are taken at the jet flow outlet end and defined as a control section I, and another finite elements are taken at the measured section in the jet flow direction and defined as a control section II;

the high-pressure gas does not receive the exogenic action by the in-process of I flow direction control section II of control section, therefore the conservation of momentum in control section I and the control section II, shows as:

m_Ⅰv_Ⅰ＝m_Ⅱv_Ⅱ(1)

high pressure causes gas can reach the sound velocity at orifice exit, and gas comes out from the export cross-section with the sound velocity, and speed is very high, consequently produces the entrainment effect, and background gas can be by the entrainment get into in the gas efflux direction, consequently control II department of cross-section gas mixture's mass flow and show:

combining the formula (1) with the formula (2) to obtain

Obtaining the mass flow of the entrainment background gas consisting of the control section I and the control section II according to the formula (3):

measuring mass flow m of gas with jet flow control section I_Ⅰ；

The high pressure causes the gas jet to reach the local sonic velocity v at the orifice exit_ⅠFinding out the sound velocity value according to the pressure;

measuring jet velocity v of control section II in jet direction by schlieren method_Ⅱ；

The data m is processed_Ⅰ、v_Ⅰ、v_ⅡSubstituting the formula (4), calculating to obtain the mass flow of the entrainment background gas from the control section I to the control section II

The technical field is as follows:

the invention belongs to the field of high-pressure gas jet mass measurement of hydrodynamics, and relates to methods for measuring mass flow rate of entrainment generated by gas jet at a sonic outlet.

Background art:

the high-pressure gas jet is widely applied to fields of aerospace, automobiles, metallurgy, chemical engineering, food processing and the like.

The high pressure causes the gas jet to reach sonic velocity at the orifice exit. When the pressure is reduced to be lower than the ambient pressure, background gas flows into the jet gas, namely is entrained into the jet gas and keeps the same speed with the jet gas, so that the mass of the moving mixed gas vertical to the section in the jet direction is continuously increased in a gas internal combustion engine in high-pressure cylinder injection, and the entrainment effect is the key for forming mixed combustible gas in the cylinder, so that the mass of the entrained background gas on different sections is necessary to obtain.

In view of the above, the present invention proposes methods of measuring background gas mass flow entrained in a cross-section perpendicular to the jet direction under sonic jet conditions.

Disclosure of Invention

The high-pressure gas flows out through the jet holes, infinite thin finite elements are taken at the jet flow outlet end and are defined as a control section I, and another infinite thin finite elements are taken at the measured section in the jet flow direction and are defined as a control section II.

The high-pressure gas does not receive the exogenic action by the in-process of I flow direction control section II of control section, therefore the conservation of momentum in control section I and the control section II, can show as:

m_Ⅰv_Ⅰ＝m_Ⅱv_Ⅱ(1)

the high pressure causes the gas to reach sonic velocity at the orifice exit, and after the gas exits the exit cross-section at sonic velocity, the velocity is very high, thus creating entrainment, and background gas will be entrained into the gas jet direction, and this entrainment will occur directly at jet path , thus controlling the mass flow of the mixed gas at cross-section ii as:

combining the formulas (1) and (2) to obtain

Obtaining the mass flow of the entrainment background gas consisting of the control section I and the control section II according to the formula (3):

experimental measurement of mass flow m of gas with jet flow control section I_ⅠA drainage method, a partial pressure method or the like may be employed.

The high pressure causes the gas jet to reach the local sonic velocity v at the orifice exit_ⅠThe sound velocity value can be found out according to the pressure.

Experimental measurement of jet velocity v of control section II in jet direction_ⅡThe jet flow penetration speed can be measured by adopting a schlieren method, and the average jet flow speed of the high-pressure gas at the section can be obtained.

According to the data substitution formula (4) in the formulae [ 0010 ], [ 0011 ] and [ 0012 ], calculating to obtain the mass flow of the background gas sucked from the control section I to the control section II

Drawings

Figure 1 is a schematic view of different control cross sections of a gas jet.

Fig. 2 is a schematic diagram of gas jet entrainment.

Fig. 3 is a calculation flow chart.

The specific implementation mode is as follows:

a flow chart is calculated with reference to fig. 3.

The mass flow of the gas at the outlet end of the jet flow is measured by experiments, and a drainage method or a partial pressure method and the like can be adopted.

The local speed of sound of the outlet cross section is calculated.

According to the data of [ 0017 ] and [ 0018 ] substituting the formula (1), the momentum of the gas at the outlet end can be calculated.

The jet velocity of the measured cross section in the jet direction was measured experimentally. The jet flow penetration speed can be measured by adopting a schlieren method, and the high-pressure gas jet flow speed at the section can be obtained.

And calculating the mass flow of the mixed gas of the section by combining momentum conservation, and obtaining the mass of entrainment background gas jetted to the section on the basis of subtracting the mass of the outlet section.