100 results about "Pore pressure gradient" patented technology

A method for detecting leakage in a pressurised medical appliance prior to normal operation, the system including an air compressor and an inflatable bag or bladder coupled to the air compressor through the intermediary of a fill valve allowing air to pass to the bladder and a vent valve for venting the system, the fill valve and the vent valve being selectively operable during said normal operation to deliver cyclical pulses of air to inflate and deflate the bladder, the detection method comprising a) opening the fill valve to vent the system to atmospheric pressure, b) closing the vent valve, c) pressurising the system by means of the air compressor to a pre-determined threshold value, d) monitoring the pressure gradient or rise over a period of time to said threshold value and e) comparing the pressure gradient over said period of time or at intervals of time within said period of time with a pre-specified pressure gradient indicative of system integrity whereby to determine the presence or otherwise of air leakage in the system.

The invention discloses a pressure expander of a centrifugal compressor. The structure of the pressure expander is improved, and high application value is achieved for further improving working performance of the pressure expander. A short blade is arranged in runners of every two adjacent long blades; the front edges of the long blades are curved surfaces and are arranged obliquely, and the included angles between front edge lines and the central axis of a wheel disc are 6 degrees to 8 degrees; the radius of curvature of the front edges of the long blades is gradually increased from the wheel disc to a wheel cover; each long blade is provided with three broken-line-shaped channels penetrating through a corresponding pressure surface and a corresponding suction surface; tail edge wing tips are arranged on the portions, located on the pressure surfaces, of the rear edges of the long blades. Occurrence of separation of airflow on the surfaces of the blades is restrained through the short blades in the runners of the adjacent long blades; the pressure differences between the pressure surfaces and the suction surfaces are reduced through the broken-line-shaped channels, the adverse pressure gradient is reduced, and separate airflow on boundary layers of the suction surfaces at the tails of part of the blades is effectively blown away; increase of wing tip vortexes generated by the pressure differences between the suction surfaces and the pressure surfaces on the rear edges of traditional wing-type blades can be restrained through parabola-shaped winglets on the tail edges.

The invention discloses a testing method for consolidation degree of soft soil foundation in the field of engineering construction, which comprises the following steps: acquiring a frequency dispersion curve by utilizing the frequency dispersion characteristics when Reyleigh waves are transmitted in a layered medium, and correlationship of the spread velocity of the Reyleigh waves and the physical-mechanical property of a soil body; calculating the wave velocity of the Reyleigh waves of a soft foundation soil layer according to the frequency dispersion curve of the Reyleigh waves; and finally, calculating the consolidation degree by combining a parameter k calculated according to the relation between a normalized shear wave velocity increment of the tested soil layer and the consolidation degree obtained by indoor resonant column tests. Compared with the prior method for calculating the consolidation degree through pore pressure, the testing method is more simple, convenient, effective and economic. The pore pressure is not needed to be tested, so the testing time is greatly saved; moreover, the prior method is easy to fail because of high requirement on the laying of a pore pressure gauge, and the results obtained by the testing method are more accurate.

Leak detection system. The system includes a structure sized to fit within a pipe for supporting at least one sensing element near an inside wall of the pipe, whereby a pressure gradient at a leak in the pipe will cause the sensing element to respond. Structure is provided for detecting movement or deformation of the sensing element, the movement or deformation indicating the presence of a leak. In a preferred embodiment, the structure includes two spaced-apart rings for supporting the at least one sensing element. The sensing element is a diaphragm in a preferred embodiment. In this embodiment, the sensing element is supported for movement with respect to the ring structure which includes sensing circuitry for detecting the movement to indicate a leak. Other embodiments employ different sensing elements that respond to pressure gradients near leaks.

A family of Radar energy Absorbing Deformable Low Drag Vortex Generators (RAD-LDVG) is described herein. This family of devices are fabricated in such a way that it can conform to aircraft surface features while reducing radar returns from structural details. Vortex generators (VGs) are typically used to reattach or smooth gross flowfields over aircraft surfaces. By doing so, an airfoil or wing can maintain attached flow at higher angles of attack and/or higher lift coefficients than one without the VGs. These devices are also used to reattach and/or smooth flows that encounter crossflow-induced instabilities and/or adverse pressure gradients on the upper surfaces of wings or near aircraft boattails. Other uses include reduction of buffet, vibration, flutter, cavity resonance or general bluff-body pressure drag reduction. Although conventional rigid VGs do generate vortical aerodynamic structures, two major problems are often experienced: i.) the inability to conform to curved surfaces, ii.) the generation of radar cross-section spikes produced by the VGs themselves.

The invention provides an in-depth profile control step by step method employing equipressure drop gradient , which relates to the technical field of deep profile control of a water flooding development oil reservoir. According to the practical condition of a test block, suitable profile control agent is selected, and the breakthrough pressure gradients of profile control agents of different compositions are tested. A stratum is divided into a near wellbore zone, a far wellbore zone and a stratum deep according to the pressure drawdown of the stratum; and the pressure gradients of the zones are different, so that slugs with different strengths are required. According to the principle of equipressure drop gradient, namely, the breakthrough pressure gradient of the profile control agent equals to the pressure gradient of the stratum, the composition of each slug is selected, profile control slugs are combined, and the combined profile control slugs are optimized according to the cost. According to the invention, profile control agents with different strengths can be placed in different positions of the stratum, and overall in-depth fluid diverting step by step of the space of the oil reservoir can be realized through the combination of profile control agents with different strengths, so that the conformance factor can be improved greatly, further the oil recovery efficiency can be improved.

The invention relates to a method for on-site testing of the start-up pressure gradient and permeability of gas in low-permeability coal reservoirs. By selecting representative blank areas in the low-permeability coal reservoirs in coal mines, drilling holes for pressure measurement and gas drainage holes are constructed. , and seal the pressure measurement borehole and the gas drainage hole respectively, observe and record the pressure gauge readings of the pressure measurement borehole and the gas flow readings of the gas drainage hole, and use the gas seepage equation and the starting pressure gradient formula to derive The permeability of the coal reservoir. This method does not need to process coal samples, and the particle size, moisture content, homogeneity, and confining pressure of the coal body are all characteristics of the coal reservoir in the real state. The permeability of the coal reservoir calculated by long-term field observation The average value is more accurate and can be used as a reference value for the coal reservoir permeability of the low-permeability coal seam in the entire mine. At the same time, this method provides a theoretically accurate and feasible method for testing the gas start-up pressure gradient and permeability of low-permeability coal reservoirs. new ideas.

The invention relates to a high pressure gas fragmentation iron ore test device. The high pressure gas fragmentation iron ore test device comprises a steel drum, a first flange, a second flange, a seal flange, an anti-explosion disk, an annular plate, a connecting rod and a high pressure gas tank. Two ends of the steel drum are provided with the first flange and the second flange respectively. The seal flange is arranged on the second flange, the anti-explosion disk is arranged between the second flange and the seal flange, the annular plate is arranged between the second flange and the steel drum, and the annular plate is connected with the second flange through the connecting rod, so that an inflation cavity is formed between the annular plate and the second flange. The high pressure gas tank (not shown) is connected with the steel drum 1 through a high pressure gas delivery pipe. According to the high pressure gas fragmentation iron ore test device, the characteristics of high density and low viscosity of high pressure gas fluid are utilized, so that the high pressure gas permeates the inside of the iron ore through joint or microcrack of the iron ore itself, and the iron ore containing the high pressure gas generates fracture and fragmentation under high pressure gradient through sudden pressure relief. The high pressure gas fragmentation iron ore test device has an important realistic significance for reducing the crushing cost of the iron ore and improving economic benefits of an enterprise.

The invention relates to a drainage consolidation method of a triaxial shear test of a soil sample. The triaxial shear test system of the invention comprises a triaxial shear tester, a pore water pressure measurement device and a peripheral pressure device, wherein a pore pressure buret and a draining buret are in parallel connection with a pore pressure pipe; the peripheral pressure device comprises an air pressure pump, a master pressure-regulating air valve, a sub-pressure-regulating air valve, a peripheral pressure valve, a master air inlet pipe and a plurality of sub-air inlet pipes, burets and a water outlet pipe, wherein a plurality of burets are positioned in parallel, and one end of each air inlet pipe is connected with the upper end of the corresponding buret. The draining consolidation method comprises the following steps: ensuring that the water surface in the draining buret and the pore pressure buret and the center height of the sample are at the same level; adjusting peripheral pressure to a needed value sigma 3, performing draining consolidation; after performing drainage consolidation for 3-6 hours, measuring and recording pore water pressure every one hour until the pore water pressure is reduced to 5% of the pore water pressure value sigma k which is measured originally, and finishing drainage consolidation. The method of the invention has the advantages of effectively shortening the draining consolidation time in the shear test and accelerating the engineering project.

The invention relates to a testing device for measuring the shearing strength parameter changes in the solidifying process of soft clay and belongs to the technical field of soft clay analyzing devices. The testing device comprises a frame, a loading plate, miniature vane shearing instruments with a pore pressure testing function, a torsion meter, a sample chamber, a measuring unit and a lifting mechanism. The loading plate is arranged above the sample chamber, and the loading plate or the sample chamber is arranged on the frame through the lifting mechanism. The measuring unit comprises sensors used for collecting pore water pressure, soil pressure, displacement and other information. By means of the testing device, a shearing failure mechanism without volume change action or a shearing failure mechanism without pore pressure action can be independently studied, a shearing failure mechanism under volume change and pore pressure coupled action can be studied at the same time, and more testing types are achieved; shearing strength changes caused by soil body changes and pore pressure changes in the loading and solidifying process of soft clay can also be studied, and the changing rules of the shear strength parameters in the whole study process along with the solidifying process can be studied.

The invention provides a transverse pressure gradient controlled ride wave forebody and air inlet channel integrated designing method and relates to a near space hypersonic flight vehicle. The method comprises the steps of designing a basic flow field required by a two-dimensional air inlet channel; confirming the position where a designed cross section is located; designing projection of front edge capture molded lines in the designed cross section according the working condition requirements and calculating projection distances from front edge points in wedge tangent planes to shock wave points in z-direction; obtaining pressure distribution of compression molded lines at the positions of the wedge tangent planes corresponding to disperse shock wave points; obtaining newly-generated two-dimensional air inlet channel compression molded lines by applying two-dimensional characteristic line method according to calculated pressure distribution; arranging the two-dimensional air inlet channel compression molded lines at the positions of the corresponding front edge capture molded lines to form a complete air inlet channel compression profile, obtaining a ride wave forebody and air inlet channel integrated device after three-dimensional modeling and finishing the transverse pressure gradient controlled ride wave forebody and air inlet channel integrated design. By adopting the method, the device can have high lifting drag characteristic, external flow resistance is reduced while engine thrust is increased.

Leak detection system. A rigid body is resiliently supported within an outer cage. Means are provided for detecting displacement of the rigid body with respect to the outer cage, the displacement indicating a leak when the rigid body is moved by a suction force generated by a local pressure gradient resulting from a leak within a pipe network. The invention allows a leak to be determined around the circumference of a pipe.

Systems and methods of numerically simulating airflow within porous materials are disclosed. According to one aspect of the present invention, engineering product represented by a finite element analysis model containing in part porous material with permeability. In each solution cycle of a time-marching simulation, each of the elements of porous material is evaluated with airflow in conjunction with the traditional mechanical response. Each element's volume change results into different air-pore pressure hence a pressure gradient, which in turn is used for airflow calculated in accordance with a fluid seepage law that depends upon permeability of the porous material. Therefore, a more realistic simulation of structural behavior of porous materials can be achieved. The volume change and pressure of each element of porous material is evaluated using ideal gas law. A general form of Darcy's law includes user control parameters is used for evaluating airflow based on the pressure gradient and permeability.

The invention provides an experimental method for determining initiation pressure gradient of seepage, and belongs to the technical field of oil and gas field development and test. The method comprises the following steps of: first, placing a rock core saturated with homogeneous liquid into a rock core holder, and exerting confining pressure to the rock core; then injecting the homogeneous liquidinto the rock core from the inlet end of the rock core holder; measuring changing data of pressure at the inlet end of the rock core holder over time; monitoring changing data of pressure at the outlet end of the rock core holder over time; stopping the experiment when the pressure at the outlet end of the core holder changes; recording duration time during which the pressure of the homogeneous liquid from the inlet end of the core holder into the core to the outlet end of the core holder changes; and repeating the steps to obtain starting pressure gradient of the homogeneous liquid seeping inthe rock core. The method is simple and rapid, and is more in line with the technical requirements of effective utilization range estimation of oilfield blocks in low-permeability reservoirs and heavy oil reservoir development technologies, and corresponding well network optimization and oil and gas well incentive measures.

The invention discloses a mattress pressure comfortableness evaluation method, which comprises the following steps of: (1) arranging a body pressure measuring instrument on a mattress, testing the body pressure distribution when the people sleep on the mattress, and obtaining body pressure distribution data; (2) performing mathematical treatment on the body pressure distribution data, and calculating and obtaining a maximum pressure, an average pressure, a maximum pressure gradient, an average pressure gradient, and a contact area; (3) giving out mattress comfortableness evaluation data after sleep experience is performed on the mattress by subjects; and (4) using a GA-Elman neural network and establishing a coupling model between body pressure distribution index data of the subjects and corresponding evaluation data, and outputting an evaluation result through the coupling model, the Ga-Elman neural network being to optimize initial network weights of an Elman neural network structure by using a genetic algorithm. The mattress pressure comfortableness evaluation method combines body pressure distribution indexes and human body evaluation data to evaluate the comfortableness of the mattress, thereby helping people to choose the mattress with better comfortableness and ensuring the people to enjoy a comfortable sleep.

A method and system for drilling a wellbore is described. The syste includes a wellbore with a variable density drilling mud, drilling pipe, a bottom hol assembly disposed in the wellbore and a drilling mud processing unit in flui communication with the wellbore. The variable density drilling mud has compressibl particles and drilling fluid. The bottom hole assembly is coupled to the drilling pipe while the drilling mud processing unit is configured to separate the compressibl particles from the variable density drilling mud. The compressible particles in thi embodiment may include compressible hollow objects filled with pressurized gas an configured to maintain the mud weight between the fracture pressure gradient an the pore pressure gradient. In addition, the system and method may also manag the use of compressible particles having different characteristics, such as size, during the drilling operations.

The invention discloses a step-by-step deep profile control method based on pressure field and flow velocity field distribution. The step-by-step deep profile control method includes the following steps: screening profile control agents according to actual stratum conditions of an oil field, conducting step-by-step profile control step dividing according to an actual stratum falloff curve, dividing a stratum into a near-well zone, a far-well zone and a stratum deep part, measuring the relationship between the profile control agent injection amount and the recovery efficiency through a physical modeling test, obtaining the optimum injection depth r0 of the profile control agents by calculating the input-output ratio, setting test conditions to measure the breakthrough pressure gradient of the profile control agents according to the flow velocity field distribution, drawing an equivalent plate of the breakthrough pressure gradient, screening a profile control agent formula of each section plug on the equivalent plate of the breakthrough pressure gradient when the breakthrough pressure gradient of the profile control agents is equal to the stratum pressure gradient according to the equal-pressure-drop gradient principle, combining the profile control section plugs, conducting cost calculation on each section plug combination, and obtaining the section plug combinations, namely the optimal section plug combination, with the lowest cost in an optimized mode.

The invention discloses a branch horizontal well mining method based on a starting pressure gradient. The branch horizontal well mining method comprises the following steps: firstly, calculating the theoretical value of the shale gas yield in a branch horizontal well; according to the theoretical value, carrying out the actual production of the branch horizontal well, and drawing a curve graph of the actual daily yield and time of the branch horizontal well; when a jump point occurs in the curve graph, adjusting the production until the jump point does not appear in the curve graph; when accumulated water yield is equal to critical water yield, determining that the branch horizontal well is scrapped. According to the branch horizontal well mining method, by adjusting the production when the jump point occurs, the output water in the horizontal wellbore can be timely carried by shale gas, the harm of the gas and water mixture returning to the bottom of the well is thus reduced and the gathering of the output water on the bottom of the well is reduced, therefore, maintenance charge is reduced, efficiency is high and maintenance cost is saved.

The invention provides a device and a method for measuring the starting pressure gradient of polymer-flooding reservoir fluid seepage. The device is characterized by comprising a pressure observation system; the upper part of an inlet end of the pressure observation system is communicated with a pressure control system; the lower part of the inlet end of the pressure observation system is communicated with an inlet end of a seepage environment simulation system; the lower part of an outlet end of the pressure observation system is communicated with an outlet end of the seepage environment simulation system; the inlet end and the outlet end of the seepage environment simulation system are respectively provided with a pressure sensor; the two pressure sensors are used for acquiring pressure signals in real time and sending the acquired pressure signals to a data acquiring and processing system by means of a signal transmission system; the data acquiring and processing system can be used for obtaining the starting pressure gradient of the fluid seepage according to the received pressure signals. The measurement method provided by the invention is visual, accurate and convenient, and can be widely applied to the measurement of the starting pressure gradient of the polymer-flooding reservoir fluid seepage.

A sealed type molten salt distillation method and a distillation device are disclosed. The method is implemented through the distillation device. The distillation device includes a distillation kettle. A sealed cavity is formed in the distillation kettle. The left side end of the sealed cavity is an evaporation zone, and the top and bottom of the right side end of the sealed cavity are a condensing zone and a collecting zone respectively. The vapour pressure of molten salt increases along with the increase of temperature, a large vapour pressure gradient can be formed through heating and cooling different parts of the vacuum distillation kettle under a sealed condition so as to drive molten salt distillation. Disadvantages of the prior art that recovery rates are low and products are scattered are overcome. Pollution and corrosion of a vacuum system by the molten slat are effectively avoided. The product recovery rate is increased.