深海环境下油液密度特性变化规律研究

Study on the Change Law of Oil Density Characteristics Based on Deep Sea Environment Model

针对深海环境下油液密度随下潜深度变化的问题,建立深海环境压力和温度模型,考虑含气率的影响分别建立纯油液密度模型和气-液两相等效密度模型,以VG32和VG64液压油实验数据对模型进行误差分析,得到其最大误差分别为0.32%、0.11%,验证了模型的可行性。综合上述模型,建立以水深为变量的等效密度模型,研究深海环境下液压介质密度的变化规律。结果表明:随水深的增加,气-液两相油液模型的等效密度较纯液压油模型的变化相对滞后,但进入深海3000 m以下后,两者相差很小,可以用纯液压油密度近似替代两相介质的密度;深海环境下随水深增加,油液等效密度呈现迅速增加、缓慢过渡、平稳增长的变化规律。具体表现为:在浅海层(<460 m),海水温度对密度变化起主导作用,等效密度随水深增加急剧增长;在中海层(460~1300 m),温度主导作用减弱,等效密度增幅变缓;在深海层(>1300 m),海水压力取代温度成为影响密度的主要因素,密度增长趋于平稳。

Aimed at the problem of oil density changing with depth in deep sea environment,the deep sea environment pressure and temperature model was established.Considering the influence of gas content,a pure oil density model and a gas-liquid two-phase equivalent density model were established respectively.The error analysis of the models was carried out with experimental data of VG32 and VG64 hydraulic oil.The maximum error of the models is 0.32%and 0.11%,verifying the feasibility of the models.Based on the above model,the equivalent density models with water depth as the variable were established,and the change law of hydraulic medium density in deep sea environment was studied.The results show that the change of the equivalent density of gas-liquid two-phase oil equivalent density model is lagged behind that of pure hydraulic oil density model with the increase of water depth.However,the difference of the density between the two models is very small when the sea water depth is more than 3000 m,and the density of pure hydraulic oil can be used to replace the density of the two-phase medium.With the increase of water depth,the equivalent density shows a growth law from fast to slow.The specific performance is:in the shallow sea layer(<460 m),the seawater temperature plays a dominant role in the density change,and the equivalent density is increased sharply with the increase of water depth;in the middle sea layer(460~1300 m),the temperature dominant effect is weakened,and the equivalent density is increased slowly;in the deep sea layer(>1300 m),seawater pressure instead of temperature becomes the main factor affecting density,and density growth tends to be stable.