Total Leakage Rate Research Articles

Tiny bubble triboelectric nanogenerator functionalized by liquid film rupture

As an important energy carrier, bubble commonly exists in undersea and liquid-gas two-phase systems. Efficiently utilizing the bubble energy is critical for potential applications in energy harvesting and sensing in two-phase environment. However, the micro liquid layer inhibits the complete contact and restricts the performance. Herein, we proposed strategies for tiny bubble triboelectric nanogenerator (TB-TENG) featuring liquid film rupture to eliminate the screen between bubble and dielectric layer. We carried out optimization design by invasively rupturing the liquid film, achieving stable open-circuit voltage peak and transferred charge of 8.3 V and 3 nC by a 110-μL bubble, with a high peak power density yielding the existing tube-based studies. Additionally, for noninvasive and spontaneous liquid film rupture, a scalable bubble regulator was fabricated, which integrated the irregularly dispersed bubbly flow into slug flow. We demonstrated the self-powered undersea gas leakage detection system combining the TB-TENG with the bubble regulator. Assisted with the good bubble regulation adaptability, the total leakage gas volume and rate were measured based on the voltage signal, with a varied leakage rate of 0.72–6 mL/min. The strategy provides insights for the related research in liquid-gas two-phase systems in nature and industry.

Assessing the performance of infrared thermography and PIV methods to identify and characterize the air inlets and outlets in wall assemblies

Building airtightness is crucial for reducing energy demand in the building sector and preventing moisture damage and indoor environment quality issues. Mandatory airtightness tests are now commonly performed in many countries to quantify the total envelope leakage rate of real buildings. For a more precise diagnosis, air leakages are usually identified by infrared thermography or visualized by smoke. However, a finer analysis is also needed to characterize precisely the air flow through specific leaks. Numerical models have been developed for this purpose but experimental data are necessary to validate them. In this paper, two experimental approaches are tested on simple light-wall assembly configurations to address this need: infrared thermography (IRT) and the innovative use of particle image velocimetry (PIV) with a specific experimental set-up and protocol developed. The results are compared with each other as well as with numerical simulations. Results showed that both techniques can be applied for the experimental characterization of the air inlet/outlet of a wall assembly with different advantages and drawbacks. IRT is easy to implement, non-intrusive, possible for in-situ investigations, but the correlation between the thermographs and the air dispersion at the outlet is not straight forward due to thermal inertia and heat conduction issues. PIV gives direct results on the velocity field and enables quantitative analysis of air flow rates for various configurations, with some limitations: a difficult implementation; restrictions on the possible infiltration velocity range and difficulties to visualize the flow exactly at the interface with the wall assembly.

Unravelling physiological and histochemical changes in two popular dessert and cooking bananas of India during fruit ripening

The physicochemical and histochemical characteristics of two consumingly divergent commercial varieties of Musaceae (Musa cv. Kanthali and Musa cv. Kacha Kela) were investigated during their postharvest ripening. The fruit peels from both cultivars were characterised by a reduction in chlorophyll contents, loosening of cortical tissues, and shrinkage of parenchymatous cells. The pulp-to-peel ratio, total soluble sugars, reducing sugar, fruit firmness, electrolyte leakage, and respiration rate were investigated along with activities of a few enzymes involved in fruit softening, namely cellulase, xylanase, invertase and glucanase. Additionally, semi-quantitative gene expression analyses with a few ripening-related genes, including ethylene biosynthesis (MaACS and MaACO), carbohydrate metabolism viz. sucrose synthase (MaSUS), sucrose phosphate synthase (MaSPS), glucanase (MaGLU), invertase (MaINV) and pectin methyl esterase (MaPME) were also carried out along with chitinase (MaCHT) in both cultivars during postharvest ripening. A faster postharvest ripening of ‘Kanthali’ than ‘Kacha Kela’ was evidenced as an outcome of the above studies.The peel histology and surface ultrastructure were examined through light microscopy and scanning electron microscopy (SEM), respectively. In light microscopy, substantial variations were noted between the cultivars, especially on peel-tissue degradation and accumulation of metabolites. The surface ultrastructure revealed temporal variations in the peel stomatal opening along with gradual depletion of surface wax. Such temporal opening of stomata was found to coincide with our earlier recorded postharvest volatiles emission patterns of respective cultivars suggesting it to be a legible vent for aroma emission.

Insulation excellence and storage dynamics in a 500-litre self-developed vehicular liquid hydrogen cylinder: thermal leakage and status analysis

Abstract Liquid hydrogen storage represents an efficient and highly promising method for hydrogen encapsulation, particularly relevant for hydrogen-powered vehicles. This paper describes a novel self-developed 500-litre vehicular liquid hydrogen cylinder featuring high vacuum multi-layer insulation (HVMLI) and eight-point support structures. The study quantitatively analyzes the heat leakage from the thermal insulation layer, support structures, and accessory pipelines of this cylinder, with a total thermal leakage rate of 11.759 W, mainly stemming from the support structure. Moreover, using the BoilFAST software, simulations were conducted to investigate variations in the pressure of the ullage space, the temperature of the stored liquid hydrogen, and the temperature of the vapor within the ullage space across different liquid filling rates and stationary periods. This paper provides valuable insights into the development of vehicular liquid hydrogen cylinders, and the simulation results improved comprehension of the internal storage status and variations of associated physical parameters.

High-capacity device-independent quantum secure direct communication based on hyper-encoding

Quantum secure direct communication (QSDC) can directly transmit secret messages through quantum channel without keys. Device-independent (DI) QSDC guarantees the message security relying only on the observation of the Bell-inequality violation, but not on any detailed description or trust of the devices’ inner workings. Compared with conventional QSDC, DI-QSDC has relatively low secret message capacity. To increase DI-QSDC’s secret messages capacity, we propose a high-capacity DI-QSDC protocol based on the hyper-encoding technique. The total message leakage rate of our DI-QSDC protocol only relies on the most robust degree of freedom. We provide the numerical simulation of its secret message capacity altered with the communication distance. Our work serves as an important step toward the further development of DI-QSDC systems.

Analysis of the Total Leakage Characteristics of Finger Seal Considering Fractal Wear and Fractal Porous Media Seepage Effects

As an advanced flexible dynamic sealing technology, the leakage characteristics of a finger seal (FS) is one of the key research areas in this technology field. Based on the fractal theory, this paper establishes a mathematical model of the FS main leakage rate considering the fractal wear effect by taking into account the influence of the wear height on the basis of the eccentric annular gap flow equation. Based on the Hagen-Poiseuille law and the fractal geometry theory of porous media, a mathematical model of the FS side leakage rate considering the fractal porous media seepage effect is developed. Then, a mathematical model of the FS total leakage rate is established. The results show that the mathematical model of the FS total leakage rate is verified with the test results, the maximum error rate is less than 5%, and the mathematical model of the FS total leakage rate is feasible. With the gradual increase in working conditions and eccentricity, the FS main leakage rate gradually increases. In addition, the effects of the fractal dimension, fractal roughness parameters and porosity after loading on the FS main leakage rate are negligible. As the fractal dimension of tortuosity after loading gradually decreases, the fractal dimension of porosity after loading gradually increases, and the FS side leakage rate gradually increases. As the porosity after loading gradually increases, the FS side leakage rate gradually increases. Under different working conditions, different fractal characteristic parameters and different porosities after loading, the weight of the FS main leakage rate is much greater than that of the FS side leakage rate by more than 95%.

Comparative modeling studies of carbon and tungsten impurity transport in the boundary plasma of EAST with a partially detached divertor condition

• The main pathways of impurity leakage from tokamak divertor target to the core plasma are illustrated by dedicated modeling. • The key physics governing impurity screenings under both attached and detached plasma conditions are clarified. • The low-Z C and high-Z W impurities have different transport properties especially under the attached divertor plasma conditions. • Both the impurity source distribution and the divertor plasma condition have great impact on the edge transport of C and W. The source and leakage of both C and W are comparatively studied for a partially detached divertor operation condition on EAST. Based on the EAST experiments, sequential SOLPS-DIVIMP simulations are carried out to study the transport of intrinsic impurities in the boundary plasma. Carbon distribution from the fluid SOLPS simulation is in good agreement with the impurity tracing results from the Monte-Carlo DIVIMP simulation. The impurity leakage processes from the divertor target to the core plasma are quantitatively analyzed and divided into three parts: the prompt redeposition, the divertor screening, and the main SOL screening. Under the partially detached divertor condition, W has a higher prompt redeposition rate and a weaker cross-field transport from the main SOL to the core region than C. However, the strong parallel impurity transport from the divertor region to the main SOL makes the total leakage rate of W two times higher than that of C. The impurity velocity gained from the ion temperature gradient force in both the near-SOL detached region and the far-SOL attached region is evaluated. The relatively higher ion temperature gradient velocity of W in the attached region is the main reason for the higher divertor leakage rate than C, and the strong W source in the far-SOL makes the leakage from the attached region more significant.

Application of reference-free natural background–oriented schlieren photography for visualizing leakage sites in building walls

Air leakage in buildings can cause health and comfort concerns for occupants and can contribute to mold growth on building materials, or in extreme conditions, rot of building materials. Unwanted air leakage through the building envelope also contributes to approximately 4 quadrillion Btu (1172 TWh) of energy consumption per year in the building sector in the United States. Locating and sealing leakage sites can improve the energy efficiency, comfort, air quality, and moisture durability of the building stock. Typical methods of finding leakage sites, such as infrared imaging and smoke tracing, rely on concurrent blower door operation, which can also measure the total leakage rate of the building. Smoke tracing can be disruptive to occupants, and infrared imaging and smoke tracing cannot measure the contribution of individual leaks to prioritize sealing efforts. In this work, an optical fluid flow imaging technique, reference-free natural background–oriented schlieren imaging, was adapted to visualize air exfiltration. This is the first step in developing a method to noninvasively locate and measure exfiltration or infiltration sites so that sealing efforts can be prioritized. Experimental results of this technique are presented, demonstrating the method's applicability to visualizing exfiltration through three common building claddings in an outdoor environment. Key variables impacting the performance of this technique when applied to building leakage are also discussed.

A Biomechanical Study on Cortical Bone Trajectory Screw Fixation Augmented With Cement in Osteoporotic Spines.

A biomechanical study. To evaluate the efficacy and feasibility of cement-augmented cortical bone trajectory (CBT) screw fixation. Forty-nine CBT screws were inserted into lumbar vertebrae guided by three-dimensionally printed templates, and then injected with 0, .5, or 1.0mL of polymethylmethacrylate. The screw placement accuracy, cement dispersion, and cement leakage rate were evaluated radiologically. Biomechanical tests were performed to measure the axial pull-out strength and torque value. Overall, 83.67% of the screws were inserted without pedicle perforation. In the 1.0mL group, cement dispersed into the pedicle zone and formed a concentrated mass more often than in the .5mL group, but not significantly more often (P > .05). The total cement leakage rate was 18.75%. Compared with the control group, the torque value was slightly higher in the .5mL group (P = .735) and significantly higher in the 1.0mL group (P = .026). However, there was no significant difference between the .5 and 1.0mL groups (P = .431). The maximal pull-out force (Fmax) was increased by 52.85% and 72.73% in the .5 and 1.0mL groups, respectively, compared with the control group (P < .05). However, the difference was not significant between the 2 cemented groups (P = .985). Cement augmentation is a useful method for increasing CBT screw stability in osteoporotic spines. The cement injection volume is recommended to be 1mL for each screw, and the cement should disperse into the vertebral body than the pedicle zones.

ON GAS AND HYDRAULIC TIGHTNESS OF LINAC ACCELERATING SECTIONS

A technique for calculating the required impenetrability of brazing linac accelerating sections cooled by water and for control of their hydraulic tightness based on the total helium leakage rate is given. Three types of cooling systems: a water stream in tubes soldered on the outer surface of the sections, a water stream along the outer surface and along the internal cooling channels in sections are considered. It is shown that the contact of accelerating sections surface with cooling water requires increasing the tightness of their soldering at least by 66 times. As an example, requirements for hydraulic and air tightness of accelerating sections for the developed accelerator LU-10 NSC KIPT are given.

Spacecraft hatch leak testing

Spacecraft hatch needs to be tested for leakage in various environments. Hatch Quick Leak Detector (HQLD) leak testing method is a convenient and effective method for the orbital hatch. Vacuum Chamber leak testing (VCLT) method is a proper integral leakage rate method for the hatch. We performed the testing in the “CMK2000” vacuum vessel. The detection principles and steps are described in detail. Leak testing was performed on all of the hatch seals using helium mass spectrometer leak detectors and special apparatus under the Thermal Vacuum testing. We performed leak testing after finishing operating the hatch in the Thermal Vacuum environment. The relative uncertainty of the total leakage rate value of the hatch is 23.6% (k = 2). The total leakage rate testing was a successful example of complex quantitative leakage rate testing in a middle vacuum chamber.

Anti-Bacterial Properties of Bletilla striata Dihydrophenanthrene Against Extended Spectrum β-Lactamases-Carrying and Carbapenem-Resistant Escherichia coli from Hospital Clinical Practice

The present study was aimed at investigating anti-bacterial effects of Bletilla striata dihydrophenanthrene (DHP) on clinically isolated Escherichia coli (E. coli), including extended spectrum β-lactamases (ESBLs)-carrying E. coli and carbapenem-resistant E. coli (CRE). The minimum inhibitory concentrations (MIC) of two extracts, DHP and residual substances extracted by ethanol and n-butanol (NBE), were determined by the serial dilution method. The light absorption value of macromolecular substances, total leakage rate, and total protein content in the nutrient solution were determined by spectrophotometric analysis. Quantification of protein expression and drug susceptibility verification were determined by mass spectroscopy. In addition, the elimination of drug-resistant plasmids was evaluated. Our data showed that the DHP had a more powerful antibacterial effect on E. coli than that of NBE, with MICs of 0.82–1.38 mg/mL and 1.07–1.51 mg/mL, respectively. In addition, DHP enhanced the absorbance value of macromolecular substances, and increased protein expression in E. coli when compared with NBE. Moreover, NBE increased the total leakage rate of small molecule substances, total protein content, and reversed drug resistance when compared with DHP. Both NBE and DHP eliminated the banding patterns related to multidrugresistant plasmids, selectively inhibited bacterial growth and reversed multidrug resistance by regulating cell membrane permeability and protein expression levels in E. coli. The reversal of drug resistance may be mediated through elimination of drug-resistant plasmids in E. coli. Therefore, DHP and NBE may be promising antibacterial drug candidates, and DHP is more likely.

Meta-Analysis Comparing WatchmanTM and Amplatzer Devices for Stroke Prevention in Atrial Fibrillation

Background: For patients with atrial fibrillation who are at high risk for bleeding or who cannot tolerate oral anticoagulation, left atrial appendage (LAA) closure represents an alternative therapy for reducing risk for thromboembolic events.Objectives: To compare the efficacy and safety of the Amplatzer and WatchmanTM LAA closure devices.Methods: A meta-analysis was performed of studies comparing the safety and efficacy outcomes of the two devices. The Newcastle-Ottawa Scale was used to appraise study quality.Results: Six studies encompassing 614 patients were included in the meta-analysis. Overall event rates were low for both devices. No significant differences between the devices were found in safety outcomes (i.e., pericardial effusion, cardiac tamponade, device embolization, air embolism, and vascular complications) or in the rates of all-cause mortality, cardiac death, stroke/transient ischemic attack, or device-related thrombosis. The total bleeding rate was significantly lower in the WatchmanTM group (Log OR = −0.90; 95% CI = −1.76 to −0.04; p = 0.04), yet no significant differences was found when the bleeding rate was categorized into major and minor bleeding. Total peridevice leakage rate and insignificant peridevice leakage rate were significantly higher in the WatchmanTM group (Log OR = 1.32; 95% CI = 0.76 to 1.87; p < 0.01 and Log OR = 1.11; 95% CI = 0.50 to 1.72; p < 0.01, respectively). However, significant peridevice leakages were similar in both the devices.Conclusions: The LAA closure devices had low complication rates and low event rates. Efficacy and safety were similar between the systems, except for a higher percentage of insignificant peridevice leakages in the WatchmanTM group. A randomized controlled trial comparing both devices is underway, which may provide more insight on the safety and efficacy outcomes comparison of the devices.

다양한 집진필터의 적용에 따른 열회수형 환기장치의 성능 변화에 대한 연구

Today, we live in a world where serious environmental problems exist such as ultrafine dust. Ultrafine dust ha many health risks and can cause various diseases and allergies. Thus, the role of the ventilation system as an air cleaning technology is becoming crucial. In this study, the performance evaluations of the total heat exchanger using several types of HEPA grade filters were conducted for total heat exchange efficiency, valid total heat exchange efficiency, leakage rate, noise, energy coefficient, and particle capturing efficiency. The H13 grade filter shows the highest total heat exchange efficiency. Also, the H13 grade shows the greatest decrease in total heat exchange efficiency considering the leakage rate. The results of the particle cleaning capacity test shows that the H12 grade filter has the best particle cleaning efficiency.

Comparative Efficacy and Safety of High-viscosity versus Low-viscosity Bone Cement in the Treatment of Osteoporotic Vertebral Fractures

This study was to compare the clinical effects of high-viscosity with low-viscosity bone cement in percutaneous vertebroplasty for the treatment of osteoporotic vertebral fracture. A total of 112 patients with osteoporotic vertebral fracture received percutaneous vertebroplasty treatment from March 2015 to March 2017 in the Zhongda Hospital Southeast University were enrolled and divided into the high-viscosity group (n=56) and low-viscosity group (n=56) according to the cement used. Visual analogue scale, Oswestry disability index, Cobb angle and leakage were observed before operation, 2 d after operation and 4 months after operation. There was no significant difference in Visual analogue scale score, Oswestry disability index score or Cobb angle between the 2 groups before operation. However, the Visual analogue scale score, Oswestry disability index score and Cobb angle of the high-viscosity group were lower than those of the low-viscosity group 2 d after operation and 4 mon after operation. Besides, the proportion of leakage into the venous area, intervertebral area, paravertebral area and the total leakage rates in the high-viscosity group were lower than those in the low-viscosity group. In conclusion, compared to the low-viscosity bone cement, the high-viscosity bone cement could significantly relieve the postoperative pain, restore the height of vertebrae and reduce the venous, intervertebral and paravertebral leakage rate. Therefore, high-viscosity bone cement can be used as the first choice for the treatment of osteoporotic vertebral fracture.

Intraoperative fluorescence angiography in colorectal surgery

Fluorescence angiography with indocyanine green (ICG-FA) is frequently used in colorectal surgery to assess the blood perfusion in the region of an anastomosis. Previous studies with ICG-FA in both open and laparoscopic surgery could show alow rate of anastomotic leakage, e.g. the PILLARII study with aleakage rate of 1.4%. This article presents own results, the current status of ICG-FA and the fields of application. The aim of the study was to analyze whether the results obtained so far with ICG-FA are sufficient to recommend an extended use of this relatively new method in colorectal surgery. From July 2009 to June 2019 a total of 378 colorectal resections (280 colon resections and 98 rectal resections) with intraoperative examination of the anastomosis using ICG-FA were performed. In 13patients (3.4%) there was reduced intraoperative perfusion, which led to achange in the operative procedure (resection of the anastomosis and new anastomosis, colostomy). The total anastomotic leakage rate was 3.7% with 8leaks in the colon (2.9%) and 6in the rectum (6.1%). Without the intraoperative change in 13patients the rate of leakages could have increased to 7.1% (27/378). The use of ICG-FA in the group of patients studied potentially led to a reduction of the leakage rate by 48%. Current publications show similar results with apotential decrease in the rate of anastomotic leaks in colorectal surgery. The results show avery low rate of anastomotic leakage when using ICG-FA. These results are promising in colorectal surgery but controlled randomized studies are lacking and should be carried out before final recommendations can be given.

Phacoemulsification cataract surgery with different cumulative energy composite parameters in patients with type 2 diabetes mellitus:therapeutic effect and complications

To evaluate the effect of different cumulative energy composite parameters on the outcomes of phacoemulsification cataract surgery in patients with type 2 diabetes mellitus. A total of 252 patients with cataract (involving 252 eyes) and type 2 diabetes mellitus received phacoemulsification cataract surgery in our hospital between January, 2017 and June, 2019. The patients were divided into group A (150 cases) and group B (102 cases) for cataract phacoemulsification with cumulative energy composite parameters of 8 and 10, respectively, and 90 nondiabetic patients received cataract phacoemulsification with a cumulative energy composite parameters of 10 served as the control. The macular thickness, best corrected visual acuity, visual acuity, and postoperative leakage in the 3 groups were evaluated at 1 week, 1 month, and 3 months after the surgery. The visual acuity was significantly improved after phacoemulsification better in all the 3 groups. At 3 months after the surgery, the proportions of patients with visual acuity ratio &lt; 0.1 or &gt;1.0, macular thickness, best corrected visual acuity and permeability differed significantly between groups A and B (P &lt; 0.05), but not between group A and the control group (P &gt; 0.05). At 1 month and 3 months after the surgery, the proportion of patients with visual acuity ratio &lt; 0.1 was significantly lower and the rate of visual acuity ratio &gt;1.0 was higher in group A than in group B. At 1 month after the operation, the total leakage rate in group A (31.1%) was higher than that in the control group (21.1%) but comparable with that in group B; at 3 months, the total leakage rates were significantly lower in group A than in group B (10.0% vs 32.4%, P &lt; 0.05), and the leakage resulted mainly from local and diffuse permeation. Phacoemulsification can effectively improve the visual acuity of cataract patients especially in non-diabetic patients. A lower cumulative energy composite parameter achieves better outcomes in type 2 diabetic patients with cataract. The macular thickness, local infiltration and diffuse leakage can be used as indicators for assessing visual recovery and stabilization after phacoemulsification.

Constant-head test at a partially penetrating well in an aquifer-aquitard system

An analytical model for describing pumping induced drawdown by constant-head test at a partially penetrating well in a leaky confined aquifer is developed by treating the leakage of aquitard storage as an interface phenomenon rather than an volumetric effect, which is the novel and never developed so far. Three different cases of remote lateral boundaries are considered in the model. The new drawdown solution in Laplace space is obtained and inverted into time-domain solution utilizing the Stehfest method. The (semi-)analytical solutions for well discharge are then obtained under three different cases. Analytical solutions in Laplace and time domains are developed for calculating the (total) leakage rate and volume across the aquitard-aquifer interface due to constant-head test at a partially penetrating well in a leaky confined aquifer, and such solutions are of great use for groundwater resource management. Based on the newly developed solutions, the distribution of wellbore flowrate and aquitard leakage are explored and the sensitivity analysis is conducted to identify the most important controlling factor. The sensitivity analysis shows that the wellbore flowrate and the drawdown in infinite (Case 1), finite (Case 2), and closed (Case 3) leaky confined aquifer systems are both sensitive to the variation of well partial penetration, well radius, and aquifer anisotropic ratio during the whole pumping period and they are most sensitive to the change of outer boundary distance at late time for Case 3. The effect of the outer boundary on the drawdown or wellbore flowrate is more significant for a shorter outer boundary distance.

Percutaneous Vertebral Augmentation for Osteoporotic Vertebral Compression Fracture in the Midthoracic Vertebrae (T5-8): A Retrospective Study of 101 Patients with 111 Fractured Segments

Data reporting percutaneous vertebroplasty (PVP) or percutaneous balloon kyphoplasty (PKP) application to the midthoracic vertebrae remain limited. This study aimed to summarize our experiences and explore the efficacy and safety of PVP or PKP in dealing with osteoporotic vertebral compression fracture (OVCF) in the midthoracic vertebrae. Patients receiving PVP or PKP for midthoracic OVCF in our institution from January 2015 to January 2018 were retrospectively enrolled. All patients were grouped according to cement augmentation procedure types, surgical approaches, and puncture routes. All patients underwent a postoperative follow-up of 2-36 months. Visual analog scale (VAS) and ECOG Scale of Performance Status scores were evaluated pre- and postoperatively. Cement distribution and rate of cement leakage were assessed by radiographs. Associations of these variables and clinical scores and radiographic indices were analyzed. A total of 101 consecutive patients with 111 fractured centrums were enrolled. Both VAS and ECOG Scale of Performance Status scores of all patients decreased significantly after the operation, and progressively decreased at the final follow-up. The cement distribution of the bipedicular group was significantly better than the unipedicular group, but the total leakage rate of the former (71.7%) was significantly higher than the latter (43.1%). The rate of epidural cement leakage in the PKP group (5.4%) was significantly lower than that of the PVP group (20.3%), whereas the left puncture group (28.6%) was significantly higher than that of the right puncture group (2.7%). PKP and a bipedicular approach can help improve cement distribution and reduce the epidural cement leakage rate and therefore should be preferred over PVP or a unipedicular approach in OVCF of the midthoracic vertebrae.

Research on the total leakage rate leak detection technology of the large spacecraft

The spacecraft is becoming bigger and bigger. This development trend brings us a strict challenge for the leak detection of spacecrafts, especially for the total leakage rate leak detection. So it is important to study the total leakage rate leak detection technology of the large spacecraft. In this paper, an idea on large flexible accumulation chamber was provided to overcome this strict challenge. But at the same time it also brings two key problems to be solved. That is how to build the large flexible accumulation chamber for accommodating the large spacecraft and whether the mixed helium gas concentration on the height direction in this flexible accumulation chamber is uniform because helium is lighter than air. The feasibility on building the large flexible accumulation chamber for the total leakage rate leak detection of the large spacecraft was firstly analyzed. Secondly, the mixed helium gas distributing rules on the height direction in the large accumulation chamber was also given from the theoretic analysis. Finally, a large flexible accumulation chamber was built for the total leakage rate leak detection of the large spacecraft and the six times repeatability tests were also finished. The results here indicated that the six times repeatability tests owned a well consistency and the large flexible accumulation chamber was suitable for the total leakage rate leak detection of the large spacecraft.