Blowing Flow Research Articles

Computational Investigation of the Slat Blowing Control for High-Lift Airfoil

Based on the characteristics of blowing control, a new technique was put forward to weaken slat cove separation and reduce noise. The effect of the slat blowing control on lift performance, the flow field and noise with a three-element high lift aerofoil was investigated by using the computational fluid dynamics (CFD) code of Fluent and the Reynolds-averaged Navier-Stokes equations. The blowing apertures were set on the lower surface of the slat. By using the slat blowing technique, the slat cove separation can be controlled efficiently and the lift coefficient increased. The aerodynamic performance varies with different blowing flow rates and angles of attack.

Approximate method of designing a two-element airfoil

An approximate method is proposed for designing a two-element airfoil. The method is based on reducing an inverse boundary-value problem in a doubly connected domain to a problem in a singly connected domain located on a multisheet Riemann surface. The essence of the method is replacement of channels between the airfoil elements by channels of flow suction and blowing. The shape of these channels asymptotically tends to the annular shape of channels passing to infinity on the second sheet of the Riemann surface. The proposed method can be extended to designing multielement airfoils.

Simultaneous measurements of glucose, oxyhemoglobin and deoxyhemoglobin in exposed rat cortex

The present work addresses the simultaneous monitoring of hemoglobin and glucose consumption in rat somatosensory cortex in vivo. We propose a method which combines two techniques: 2-dimensional optical imaging and an amperometric microbiosensor. The mounted setup optimizes the space in the cranial window so that three micro-electrodes can be inserted: glucose microbiosensor, sentinel and stimulating electrode as well as the holder to manipulate the optical fiber. Additionally, a tool based on graphical user interface programming has been developed to visualize a two-dimension spectral map of oxy-, deoxy- and total hemoglobin, HbO 2, HbR and HbT respectively, in the cortex. Our results showed a good sensitivity, selectivity and spatial resolution for both methods. Relevant hemodynamic responses had a common central focus (at the site of the stimulus) which later segregated to other vascular compartments. A good linear relationship between extracellular glucose concentration and HbO 2 values during brain activation after local electrical stimulation was observed for electrochemical and optical recordings ( R 2 values were over 0.94). Time courses between glucose and HbO 2 signals showed a temporal delay ranging from 1 s to 2 s, suggesting that both variables are not always coupled. The temporal mismatching reported here, provides in vivo evidence that supports a neuronal hypothesis: cerebral blow flow and oxidative metabolism are driven in parallel by neural activity – rather than a concatenation of events (‘in-series’ events) occurring at sites of neuronal activation.

Using to Determine Inhaled Contaminant Volumes and Blower Effectiveness in Several Types of Respirators

This experiment was conducted to determine how much contaminant could be expected to be inhaled when overbreathing several different types of respirators. These included several tight-fitting and loose-fitting powered air-purifying respirators (PAPRs) and one air-purifying respirator (APR). CO2 was used as a tracer gas in the ambient air, and several loose-and tight-fitting respirators were tested on the head form of a breathing machine. CO2 concentration in the exhaled breath was monitored as well as CO2 concentration in the ambient air. This concentration ratio was able to give a measurement of protection factor, not for the respirator necessarily, but for the wearer. Flow rates in the filter/blower inlet and breathing machine outlet were also monitored, so blower effectiveness (defined as the blower contribution to inhaled air) could also be determined. Wearer protection factors were found to range from 1.1 for the Racal AirMate loose-fitting PAPR to infinity for the 3M Hood, 3M Breath-Easy PAPR, and SE 400 breath-responsive PAPR. Inhaled contaminant volumes depended on tidal volume but ranged from 2.02 L to 0 L for the same respirators, respectively. Blower effectiveness was about 1.0 for tight-fitting APRs, 0.18 for the Racal, and greater than 1.0 for two of the loose-fitting PAPRs. With blower effectiveness greater than 1.0, some blower flow during the exhalation phase contributes to the subsequent inhalation. Results from this experiment point to different ways to measure respirator efficacy.

Color Doppler ultrasonographic findings in active ankylosing sacroiliitis

Objective To evaluate the color Doppler ultrasonographic findings of active ankylosing sacroiliitis.Methods Thirty three patients (66 sacroiliac joints in total) with active ankylosing sacroiliitis identified by MRI and twenty eight healthy volunteers (56 sacroiliac joints) underwent color Doppler ultrasound examinations of sacroiliac joints.Degree of blood flow within and around the sacroiliac joints was evaluated by semi-quantitative scale (0 - 4 grade).For arteries, resistive index was also measured.Statistical analyses were performed to compare blood flow demonstration rate, blood flow signal scale distribution,degree of blow flow and RI value between the two groups.Results Higher blood flow demonstration rate was found in patients with active ankylosing sacroiliitis(60/66,90.1%) than control group (25/56,44.6%)( P = 0.000).The scale distribution and degree of blow flow between these two groups were statistically different (all P = 0.000) ,with mainly 2～3 grade for the patients and 0～1 grade for the control.Mean value of RI in the patients was 0.57 ± 0.07, which was lower than the control (0.66 ± 0.04, P = 0.000).Conclusions Patients with active ankylosing sacroiliitis tend to have higher degree of blood flow in sacroiliac joints and lower RI values of artery.Color Doppler ultrasound may help to evaluate the activity of ankylosing sacroiliitis. Key words: Ultrasonography,Doppler,color; Spondylitis,ankylosing; Sacroiliac joint

A New Endovascular Approach to Exclude Isolated Bilateral Common Iliac Artery Aneurysms

A new endovascular procedure is reported to treat bilateral common iliac artery (CIA) aneurysms extending to both iliac bifurcations.The left internal iliac artery (IIA) was first embolised, two overlapped Viabahn endografts were delivered from the right IIA to the distal aorta and, finally, CIA aneurysms excluded using iliac contralateral leg and extension endografts from the distal aorta to both external iliac arteries, applying a combined ‘chimney-graft/double-barrel’ technique.This procedure may extend the limits of conventional iliac endografting by preserving blow flow to at least one IIA using off-label commercially available devices, avoiding associated open surgical procedures.

Aero‐acoustic simulations of small scale electronic cooling blowers.

The noise emission of small radial blowers is important for the cooling of notebook systems. It has been demonstrated that airflow simulations for these radial blowers can be performed to predict the blower performance, even in the presence of inlet restrictions. The current paper presents an extension of this work to include predictions of the radiated acoustic noise. The calculated blower flow field is used as an input for a second stage aero‐acoustic prediction. This paper outlines two methods. The first method uses a free field approach based on the Ffowcs‐Williams and Hawkings analogy. The second approach constructs a rotating fan source, the magnitude of which is determined by integrating the pressure across a number of blade segments. The radiated field is then determined in a boundary element calculation, both for a free field and in the presence of the fan enclosure. Results for both methods are presented and compared to experimental data.

Control and management of the out-of-furnace treatment of metal using ladle vibrations

A monitoring technique is proposed and subjected to laboratory and full-scale tests. The energy of a vibration signal in an informative frequency range is found to depend on the gas flow rate and blowing (bubble, jet) conditions. An experimental version of the process control system is tested under industrial conditions.

Blood pressure and renal blow flow responses in heme oxygenase-2 knockout mice

Heme oxygenase (HO) is the enzyme responsible for the breakdown of heme-generating carbon monoxide (CO) and biliverdin in this process. HO-2 is the constitutively expressed isoform in most tissues, such as the kidney and vasculature. CO generated by HO is believed to be an important vasodilator in the renal circulation along with another gas, nitric oxide (NO). To determine the importance of HO-2 in the regulation of blood pressure and renal blood flow (RBF), we treated HO-2 knockout (KO) mice chronically with either ANG II or N(G)-nitroarginine methyl ester (l-NAME). Basal blood pressures were not different between wild-type (WT), heterozygous (HET), or KO mice and averaged 113 +/- 3 vs. 115 +/- 2 vs. 116 +/- 2 mmHg. Similar increases in blood pressure to chronic ANG II as well as l-NAME treatment were observed in all groups with blood pressures increasing an average of 30 mmHg in response to ANG II and 15 mmHg in response to l-NAME. Basal RBFs were not different between the groups averaging 6.0 +/- 0.5 (n = 6) vs. 4.8 +/- 0.6 (n = 10) vs. 5.8 +/- 0.7 (n = 6) ml*min(-1)*g(-1) kidney weight in WT, HET, and KO mice. HO-2 KO and HET mice exhibited an attenuated decrease in RBF in response to acute administration of ANG II, while no differences were observed with l-NAME. Our data indicate that blood pressure and RBF responses to increased ANG II or inhibition of nitric oxide are not significantly enhanced in HO-2 KO mice.

Methodology for development of a physiological model incorporating CYP3A and P-glycoprotein for the prediction of intestinal drug absorption

The small intestine poses a major barrier to the efficient absorption of orally administered therapeutics. Intestinal epithelial cells are an extremely important site for extrahepatic clearance, primarily due to prominent P-glycoprotein-mediated active efflux and the presence of cytochrome P450s. We describe a physiologically based pharmacokinetic model which incorporates geometric variations, pH alterations and descriptions of the abundance and distribution of cytochrome 3A and P-glycoprotein along the length of the small intestine. Simulations using preclinical in vitro data for model drugs were performed to establish the influence of P-glycoprotein efflux, cytochrome 3A metabolism and passive permeability on drug available for absorption within the enterocytes. The fraction of drug escaping the enterocyte (F(G)) for 10 cytochrome 3A substrates with a range of intrinsic metabolic clearances were simulated. Following incorporation of P-glycoprotein in vitro efflux ratios all predicted F(G) values were within 20% of observed in vivo F(G). The presence of P-glycoprotein increased the level of cytochrome 3A drug metabolism by up to 12-fold in the distal intestine. F(G) was highly sensitive to changes in intrinsic metabolic clearance but less sensitive to changes in intestinal drug permeability. The model will be valuable for quantifying aspects of intestinal drug absorption and distribution.

Failure analysis on a primary superheater tube of a power plant

In this paper failure analysis on the SA213-T12 superheater tube by visual inspection, in situ measurements of hardness and finite element analyses is presented. A primary superheater tube has failed with a wide open burst after running at around 28,194 h. Heavy clinkers were found to almost entirely cover the primary superheater region. In situ hardness measurements were carried out on the selected primary superheater first row tubes at the middle region between furnace rear screen tube and primary superheater blower flow path. Hardness measurements are also taken on the as-received failed tube. Finite element analyses on possible features prior to failure are also conducted in order to illustrate and deduce the failure mechanism and failure root cause. Localized short-term overheating of the tube due to localized and concentrated flue gas flow resulted in a failure of the primary superheater tube.

Medical Treatment of Chronic Venous Insufficiency

Chronic venous insufficiency (CVI) of the lower extremities is a complicated disorder that affects the productivity and well-being of millions of people worldwide. Management requires careful differential diagnosis and a systematic long-term multidisciplinary care effort directed toward realistic goals within the context of the patient’s lifestyle. Patients suffering from any class of the Clinical, Etiological, Anatomical, Pathophysiological (CEAP) classification of chronic venous disease (CVD) may be symptomatic (C0s-C6s). Leg heaviness, discomfort, itching, cramps, pain, paresthesia and oedema (C3) are the most frequent manifestations of CVD and a major reason for medical consultation. The standard treatments for venous disease of the lower limb include compression bandaging and stocking as well as surgical removal of varicose veins. Drugs for the venous system were initially called phlebotonics as they were believed to act on venous tone. They are still largely used in the symptomatic treatment of CVI and to make patients more comfortable. Phlebotropic drugs, in their modern form, are aimed at a wide range of processes. They are naturally occurring, seminatural or synthetic substances, some of them combining two or more active principles to improve the efficacy. Most of these belong to the flavonoid family (such as diosmine, esperidine, troxoerutine, oxoerutine, etc.) and others are capillary protecting substances as escine, centella asiatica, bilberry anthocyanosides. Flavonoid drugs have been widely used in the management of the symptom of venous disease for many years and have recently been studied in some detail to assess their effects on the microcirculation. Phlebotropic drugs are widely prescribed and marketed in Italy, France, Germany and other parts of Europe. Their mechanisms of action vary, but their main property is activation of venous and lymphatic return. The effects of phlebotropic drugs on physiological parameters such us venous tone, venous haemodynamics, capillary permeability and lymphatic drainage have been studied by many well-conducted randomized, double-blind clinical trials. In particular, phlebotropic drugs participate in the heamodynamic re-equilibrium of the microvascular system consisting in reducing capillary permeability by increasing its resistance with the consequent reduction of interstitial fluid. A series of drugs have been recently introduced for the treatment of severe CVI (CEAP 4/5/6), as co-adjuvants. They are antithrombotic drugs (sulodexide, heparan sulfate, defibrotide) and vasodilators (pentoxifyllin and prostaglandin E1) for their specific action on endothelial alterations and blow flow patterns, and on microthrombi and their oxygen barrier effect.

Cerebellar diaschisis and contralateral thalamus hyperperfusion in a stroke patient with complex regional pain syndrome

We present a right-hemispheric stroke patient with complex regional pain syndrome (CRPS). The regional cerebral blow flow (rCBF) as determined using single photon emission computed tomography (SPECT) showed contralateral increase of tracer uptake in the left thalamus accompanied by crossed cerebellar diaschisis (CCD) in the left cerebellum. After rehabilitation, the CRPS in the right upper extremity recovered, although hemiplegia persisted on the left limbs. The rCBF determined a second time using SPECT showed that uptake was normal in the bilateral thalami, basal ganglia and bilateral cerebella. At a 6-month follow-up, the CRPS had not recurred. Our findings show that analysis of rCBF by SPECT is useful for the clinical evaluation and follow-up of CRPS. To the best of our knowledge, this is the first reported case with this particular pattern of symptoms amd symptom resolution.

MRI findings in aphasic status epilepticus

Ictal-MRI studies including diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI), and MR-angiography (MRA) in patients with aphasic status epilepticus (ASE) are lacking. In this report, we aim to describe the consequences of the ASE on DWIs and its impact on cerebral circulation. We retrospectively studied eight patients with ASE confirmed by ictal-EEG, who underwent ictal-MRI shortly after well-documented onset (mean time delay 3 h). ASE consisted in fluctuating aphasia, mostly associated with other subtle contralateral neurological signs such as hemiparesia, hemianopia, or slight clonic jerks. In MRI, six patients showed cortical temporoparietal hyperintensity in DWI and four of them had also ipsilateral pulvinar lesions. Five patients showed close spatial hyperperfusion areas matching the DWI lesions and an enhanced blow flow in the middle cerebral artery. Parenchymal lesions and hemodynamic abnormalities were not associated with seizure duration or severity in any case. The resolution of DWI lesions at follow-up MRI depended on the length of the MRIs interval. In patients with ASE, lesions on DWI in the temporo-parietal cortex and pulvinar nucleus combined with local hyperperfusion can be observed, even when they appear distant from the epileptic focus or the language areas.

Human Subject Testing of Leakage in a Loose-Fitting PAPR

Leakage from loose-fitting PAPRs (powered air-purifying respirators) can compromise the safety of wearers. The Martindale Centurion MAX multifunction PAPR is a loose-fitting PAPR that also incorporates head, eye, and ear protection. This respirator is used in mines where coal dust usually is controlled by ventilation systems. Should the respirator be depended on for significant respiratory protection? Ten human volunteers were asked to wear the Centurion MAX inside a fog-filled chamber. Their inhalation flow rates were measured with small pitot-tube flowmeters held inside their mouths. They were video imaged while they breathed deeply, and the points at which the fog reached their mouths were determined. Results showed that an average of 1.1 L could be inhaled before contaminated air reached the mouth. As long as the blower purges contamination from inside the face piece during exhalation, the 1.1 L acts as a buffer against contaminants leaked due to overbreathing of blower flow rate.

수직벽 전방에서의 흡입/토출을 이용한 후류제어 연구

The effect of periodic blowing and suction of upstream flow on the separated shear flow behind the vertical fence was experimentally investigated. The fence was submerged in the turbulent shear flow and DPIV method was used to measure the instantaneous velocity fields around the fence. Periodic blowing and suction flow was precisely generated by the syringe pump. Spanwise nozzle made 2D planar periodic jet flow in front of the fence and the effect of frequency and maximum jet velocity was studied. From the results, the reattachment length can be reduced by 60% of uncontrolled fence case under the control.

A valveless micropump for bidirectional applications

This paper describes a new valveless micropump for bidirectional use. The micropump was fabricated by bonding a fluidic channel and a membrane actuator. The fluidic channel was etched on a glass substrate and the membrane actuator was made on a silicon wafer. The membrane is actuated by a piezoelectric ceramic (PZT) plate so that the membrane generates blowing and suction flows successively along an oblique channel which is connected to the main channel. A blowing flow from an oblique channel into the main channel generates forward flow in downstream, while a suction flow generates the smaller reverse flow in downstream. Therefore, the overall flow in the main channel has a downstream flow and it can have a directional characteristic when two oblique channels are used. The performance of the micropump depends on the geometry of the fluidic channel, driving frequency and voltage of the actuator. The geometry of the micropump was optimized by numerical analysis and the performance test was done under various operating conditions. The maximum flow rate was 323μl/min and the maximum back pressure was 294Pa when the membrane actuator of 10mm×10mm was driven at 130Hz and 385V.

Aerodynamic jet steering using steady blowing and suction

An aerodynamic jet steering scheme using a combination of blowing and suction near the exit plane of the primary jet is demonstrated. Previous studies involving synthetic jet actuators have shown that jet steering or vectoring is achieved when primary jet fluid is drawn into the suction slot, and that the vectoring force increases with primary jet speed. These studies were limited by the high-actuation frequencies required to maintain vectoring at high primary jet speeds. The present steady technique does not suffer from this limitation, and requires suction and blowing flow rates which are a small fraction of that of the primary jet. This arrangement is studied experimentally and numerically. The results are presented primarily in terms of turning angle. It is found that for sufficient blowing flow rates (similar to the suction flow rate) the resultant turning angle increases linearly with the suction flow rate regardless of Reynolds number (up to 21,000). For insufficient blowing, the jet may be turned in the opposite direction.

EFFECT OF ACETAZOLAMIDE IN MOYAMOYA DISEASE

Objectives: Acetazolamide (AZD) can ameliorate transient neurologic symptoms that are seen in some patients with moyamoya disease (MD), and this may be related to its effects on cerebral blow flow (CBF). In order to further understand the mechanisms we examined the effects of AZD clinically and hemodynamically in a patient with MD.

Increased immunohistochemical expression of thrombomodulin at placental perivascular myofibroblast in severe preeclampsia (PE).

The presence of pro-coagulant and anti-coagulant components of the placental vascular endothelium and syncytiotrophoblast are essential for homeostasis. Vascular endothelium prevents blood clot formation in vivo by involving a cell surface thrombin-binding glycoprotein, thrombomodulin (TM), that activates plasma anti-coagulant protein C. The TM levels increase during pregnancy, but the fibrinolytic capacity diminishes. Since vascular lesions with placental coagulation disorders can be associated with preeclampsia (PE), we hypothesized that TM expression in the stem villous vasculature and syncytiotrophoblast of the placenta are impaired in PE. Plasma and placental tissue samples were collected from PE (n=12) and normotensive pregnant patients (n=11). Patient's gestational age was 35.7+/-1.2 (normotensive) and 30.6+/-1.5 weeks (PE). Blood samples were drawn 30 min before delivery. Serum PAI-1 and PAI-2 antigens were determined by enzyme-linked immunoabsorbent assay (ELISA). A monoclonal antibody specific for TM was used for immunohistochemical tissue staining (ABC) and the staining was quantified by semi quantitative scores. Results show no intensity differences at the apical syncytiotrophoblast between the two groups. However, in preeclamptic placenta, TM expression diminished in the endothelium of the stem villi arteries and increased in the perivascular and stromal myofibroblats in cases of severe PE. TM changes were associated with an increased PAI-1/PAI-2 ratio. It is suggested that in severe PE, the decreased placental blood flow may be due to structural and functional impairment of the endothelium of the stem villi vessels and the surrounding perivascular and stromal myofibroblast, by increasing TM expression which may modulate fetal blow flow in the villous tree.