小动物呼吸生理实验中整体体积描记箱内压力变化的空气动力学研究

发布时间：2018-04-18 05:15

本文选题：Boyle定律 + Poiseuille定律　；参考：《浙江大学》2007年博士论文

【摘要】： 研究背景体积描记法广泛应用于小动物的呼吸生理实验中，常用的体积描记法有整体体积描记法和双室体积描记法，可以获得小动物的潮气量等呼吸生理参数。整体体积描记法按照测试原理的不同，又可分为压力型体积描记法和流量型体积描记法。根据Fenn的原理，压力型体积描记箱内压力变化与小动物的潮气量成正比。而流量型体积描记箱的测量基础为Poiseuille定律，即进出描记箱的空气流量与压力变化成正比。对流量变化取积分，可以得到小动物的潮气量。在压力型体积描记法测量小动物呼吸生理数据时，常用Boyle定律作为计算依据。但这一定律属于空气静力学原理，其应用的前提是理想气体处于静止状态。而小动物在体积描记箱内呼吸时，描记箱内空气处于持续流动状态，这些流动的空气将对体积描记箱内施加一个附加的压力。因此，静力学的Boyle定律可能不适合分析和解决流动空气问题。 Poiseuille定律的使用前提是流动空气通过固定的规则的通道、且气流处于层流状态。而在描记箱内，空气先有一个压缩过程，且描记箱的规格与描记箱的出口规格相差甚远，流动空气在描记箱内显然处于紊流而非层流状态。因此，空气在描记箱中的流动和压缩可能影响Poiseuille定律在计算时的使用。我们首次提出从空气动力学考虑描记箱内压力变化问题，包括空气在其中的压缩和流动对压力变化的作用。研究目的本研究中，我们试图从空气动力学角度解释体积描记箱内压力变化问题。 1．在讨论压力型体积描记箱内压力变化方面，我们从理论推导及实验两方面证明Boyle定律不适合于小动物的容量变化的计算以及空气在描记箱内流动会产生附加的压力变化，并给出初步的关于压力变化的空气动力学相关公式。 2．从理论和实验两方面证明Poiseuille定律在计算容量变化时存在缺陷，空气在描记箱内流动会影响压力变化积分的计算。研究方法在研究的第一部分，我们先从空气动力学角度，由理论上推导压力型体积描记箱内压力变化的公式。然后设计3个实验证实理论推导。实验1：往体积描记箱内注入0.1ml，0.2ml，和0.4ml空气，并测量压力变化，以证实空气的流动是否影响压力型体积描记箱内压力变化。实验2：往体积描记箱内输入不同容量和频率的空气，以观察当气体输入在不同频率时描记箱内的压力是否不同，即证明空气流动的速度对压力的影响。实验3：用呼吸机和微量加样器制造不同类型的流量，再利用二者以固定频率相同容量往体积描记箱内通气，验证不同流量产生的压力变化是否不同。研究的第二部分，我们同样先从理论上对流量型体积描记箱内压力变化的积分推导出相应的公式，再从实验方面进行证明。实验4：用小动物呼吸机以不同容量在不同频率下向体积描记箱内通气，以观察空气在其中流动的速度快慢是否对压力变化积分有作用。实验5：用呼吸机和微量加样器制造不同类型的流量，利用二者以固定频率相同容量往体积描记箱内通气，验证不同流量产生的压力变化积分是否不同。研究结果第一部分的理论推导结果表明，空气输入体积描记箱后产生的压力变化主要来源于两方面：其一是遵循Boyle定律，另一部分基于动量守恒定律。同时，当输入气体的流量是时间的不同函数时，体积描记箱内压力变化仍将不同。实验1：在空气注入压力型体积描记箱后，描记箱内压力迅速上升至一个高峰，然后下降至一个高于0cmH_2O的基线压，峰压显著高于基线压(P＜0.001)。实验2：随着流动空气的频率增加，描记箱内压力变化幅度亦增加，不同频率通气产生的压力变化之间具有显著性统计学差异(P＜0.001)。实验3：以相同的0.5HZ频率相等的容量注入空气时，小动物呼吸机产生的压力变化幅度显著高于微量加样器(P＜0.001)。呼吸机产生的流量曲线几乎为水平线，而微量加样器的流量曲线明显为非直线型，，与呼吸机的流量显著不同。第二部分的研究对象为流量型体积描记箱内压力变化的积分。我们的理论推导结果表明，描记箱内压力积分并不与空气的容量变化成正比，而受输入空气容量和频率共同影响。而且，当流量变化为时间的不同函数时，体积描记箱内压力积分也将不同。实验4：随着通气频率的增加描记箱内压力变化的积分变小。重复测量方差分析显示，在容量主效应(F=39885.639，P＜0.001)和频率主效应(F=1083.922，P＜0.001)均存在显著性差异。在每两个频率组间存在显著性差异(P＜0.001)。实验5：尽管以同样容量0.5HZ频率向体积描记箱内通气时，小动物呼吸机产生的压力积分与微量加样器显著不同(F=8066.266，P＜0.001)。结论 1．当用压力型体积描记法测量小动物容量变化时，Boyle定律并不能成立，即此时压力变化不与容量变化成正比。流动空气会产生一个附加压力，后者遵循空气动力学原理。 2．压力型体积描记箱内空气变化的容量和速度共同导致压力变化，而且，空气变化的流量类型也显著影响描记箱内压力变化。 3．用流量型体积描记法测量小动物容量变化时，Poiseuille定律并不完全适合于潮气量的计算。 4．流量型体积描记箱内变化空气的容量和速度共同作用于该描记箱内压力变化积分。变化空气的流量类型也显著地影响压力变化的积分。 5．当用整体体积描记法测量小动物的肺功能时，应更多从流体力学原理出发考虑压力和容量变化，以获得潮气量或其他容量的精确计算。
[Abstract]:Background of the study

Volume tracing method is widely used in the respiration physiology experiment of small animals , and the commonly used volume tracing method has the whole volume tracing method and the double - chamber volume tracing method , so that the respiratory physiological parameters such as tidal volume of small animals can be obtained .

According to Fenn ' s principle , the pressure change is proportional to the tidal volume of small animals .

This law belongs to the principle of aerostatic mechanics . However , the law belongs to the principle of aerostatic mechanics , and the premise of the application is that the ideal gas is in a stationary state .

however , that flow and compression of the air in the stroke tank may affect the use of Poiperiille ' s law at the time of calculation .

We first put forward the question of pressure change from aerodynamics into account , including the effect of compression and flow of air on the pressure change .

Purpose of study

In this study , we try to explain the problem of pressure change in a volume graph from an aerodynamic angle .

1 . In discussing the pressure changes in the barograph box , we prove that the calculation of the volumetric changes in the small animals is not suitable for the calculation of the change of the capacity of the small animals and the flow of the air in the tracing box can produce additional pressure changes from the theoretical derivation and the experiment , and the preliminary aerodynamic correlation formula for pressure change is given .

2 . From two aspects of theory and experiment , it is proved that Poiperiille ' s law has defects in the calculation of capacity change , and the flow of air in the tracing box can affect the calculation of the integral of pressure change .

Research Methods

In the first part of the study , we first derive the formula of pressure change in the pressure - type volume graph from the aerodynamic angle , and then design 3 experiments to confirm the theoretical derivation .

Experiment 1 : 0.1 ml , 0.2 ml , and 0.4 ml of air were injected into the volume graph , and the pressure changes were measured to confirm whether the flow of air affected the pressure change in the pressure type volume stroke tank .

Experiment 2 : Enter different volume and frequency air into the volume graph box to observe whether the pressure in the stroke tank is different when the gas is input at different frequencies , that is , the influence of the velocity of the air flow on the pressure is proved .

Experiment 3 : The ventilator and microinjector were used to manufacture different types of flow , and the same volume of the fixed frequency was used for ventilation in the volume tracing box to verify whether the pressure changes caused by different flow rates were different .

In the second part of the study , we also derive the corresponding formula from the theory of the integral of the pressure change in the flow - type volume graph , and then prove it from the experimental aspect .

Experiment 4 : A small animal ventilator is used to ventilate the volume stroke tank at different frequency under different frequency , so as to observe whether the velocity of the air flow is slow or not and the integral of the pressure change has effect .

Experiment 5 : The ventilator and microinjector were used to manufacture different types of flow . Both of them were ventilated with the same capacity of fixed frequency to the volume tracing box to verify whether the pressure change points produced by different flow rates were different .

Results of the study

The theoretical derivation of the first part shows that the changes of the pressure generated after the air input volume stroke are mainly derived from two aspects : one is to follow the law of boyle and the other is based on the law of conservation of momentum . At the same time , when the flow rate of the input gas is a different function of time , the pressure change in the volume stroke tank will still be different .

Experiment 1 : After air injection into the pressure type volume tracing box , the pressure in the stroke box rapidly increased to a peak , then decreased to a baseline pressure higher than 0 cmH _ 2O , and the peak pressure was significantly higher than the baseline pressure ( P & lt ; 0.001 ) .

Experiment 2 : With the increase of the frequency of the flowing air , the amplitude of the pressure change in the stroke box also increased , and there was a significant difference between the changes of pressure in different frequency ventilation ( P & lt ; 0.001 ) .

Experiment 3 : When injecting air at equal volume of 0.5HZ , the amplitude of pressure change produced by ventilator was significantly higher than that of microinjector ( P < 0 . 001 ) . The flow curve generated by ventilator was almost horizontal line , and the flow curve of microinjector was obviously non - linear , which was significantly different from that of ventilator .

The research object of the second part is the integral of the pressure change in the flow - type volume graph . The theoretical deduction results show that the pressure integral in the stroke tank is not directly proportional to the change of the capacity of the air , but is influenced by the capacity and frequency of the input air . Furthermore , when the flow changes to different functions of time , the pressure integral in the volume stroke tank will also be different .

Experiment 4 : With the increase of ventilation frequency , the integral of pressure change in the box became smaller . The repeated measurement variance analysis showed that there was a significant difference between the main effect of capacity ( F = 39885.639 , P < 0.001 ) and the main frequency effect ( F = 1083.922 , P < 0.001 ) . There was a significant difference between the two groups ( P < 0.001 ) .

Experiment 5 : The pressure integration produced by the small animal ventilator was significantly different from that of the microinjector ( F = 8066.266 , P < 0.001 ) , although ventilation was performed at the same capacity of 0.5 Hz to the volume stroke tank .

Conclusion

1 . When measuring the change of the capacity of a small animal by a pressure - type volume tracing method , the law of boyle cannot be established , that is , the pressure change is not proportional to the change in capacity at this time . The flowing air creates an additional pressure which follows the principle of aerodynamics .

2 . The volume and velocity of the changes in the air in the pressure - type volume graph cause the pressure change , and the flow type of the air change also significantly affects the pressure change in the stroke tank .

3 . When the volume change of small animals is measured by the flow - type volume tracing method , the Poiperiille ' s law is not completely suitable for the calculation of tidal volume .

4 . The volume and velocity of the variable air in the flow volume graph are combined to the pressure change integral in the box . The flow rate of the variable air also significantly affects the integral of the pressure change .

5 . When measuring the lung function of a small animal by an overall volume tracing method , the changes in pressure and capacity shall be taken into account from the fluid mechanics principle to obtain accurate calculation of tidal volume or other capacity .

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2007
【分类号】：R33

【参考文献】