Head Of Turbinate Research Articles

Bidirectional Power Performance of a Tidal Unit with Unilateral and Double Guide Vanes

To improve the bidirectional power performance of a tidal unit, two designs were investigated. The use of unilateral or double guide vanes in a tubular tidal unit influences the performance of the hydraulic unit. Based on the N-S equations and the RNG k-ε turbulence model, the SIMPLEC algorithm was used for 3D steady-state numerical simulation of the entire turbine flow passage with unilateral and double guide vanes. The internal flow condition under positive and reverse power generation conditions was also analyzed. At the same time, the turbine, with a runner 1.6 m in diameter, was scaled down to 0.35 m diameter for model tests. The model tests were based on a multifunction hydromechanical test bench at Hohai University. The water head, discharge, and torque of the tubular turbine were, respectively, tested using a pressure difference sensor, electromagnetic flow meter, and torque meter under different guide-vane openings. The results show that turbine efficiency in the model test is slightly lower than that predicted by numerical simulation under the same conditions. However, the difference is not large. With double side guide vanes, although the efficiency of positive power generation decreased, the efficiency of reverse power generation is greatly improved.

The impact of inlet angle and outlet angle of guide vane on pump in reversal based hydraulic turbine performance

In this paper, in order to research the impact of inlet angle and outlet angle of guide vane on hydraulic turbine performance, a centrifugal pump in reversal is adopted as turbine. A numerical simulation method is adopted for researching outer performance and flow field of turbine. The results show: inlet angle has a crucial role to turbine, to the same flow, there is a noticeable decline for the efficiency and head of turbine with the inlet angle increases. At the best efficiency point(EFP),to a same inlet angle, when the inlet angle greater than inlet angle, velocity circulation in guide vane outlet decreases, which lead the efficiency of turbine to reduce, Contrarily, the efficiency rises. With the increase of inlet angle and outlet angle, the EFP moves to the big flow area and the uniformity of pressure distribution becomes worse. The paper indicates that the inlet angle and outlet angle have great impact on the turbine performance, and the best combination exists for the inlet angle and outlet angle of the guide vane.

Measurements of normal nasal airway assessed by 3-dimensional computed tomography in Chinese children and adolescents

ObjectiveTo establish normative data of nasal airway dimensions in Chinese children and adolescents by age and sex. MethodsCT images of 281 Chinese children and adolescents (140 girls and 141 boys) aged from 6 to 18 years (yr) were selected among the patients who visited in Shanghai Ninth People's Hospital from September 2009 to August 2010. Subjects were divided into four age groups as group 1 (6–9yr), group 2 (10–12yr), group 3 (13–15yr), and group 4 (16–18yr). Child was defined as 6–12yr, and adolescent as 13–18yr. Nasal parameters were as follow: nasal volume (NV), length of nasal airway (NL), minimal cross-section area (CSA 1) and its location (D 1), inferior turbinate head's location (D 2) and its airway cross-section area (CSA 2), and cross-sectional area of choanal (CSA 3). ResultsThere was no significant sex dimorphism in nasal parameters in children (group 1 and group 2). In adolescents, male's nasal dimension were larger than female's. CSA 1, D 1, CSA 2, CSA 3, NL and NV correlated with age in male and female respectively. ConclusionsVolume, length and cross-section area of nasal airway were correlated with age in Chinese children and adolescents aged from 6 to 18yr. In children, nasal conformations of male and female are similar. In adolescents, sex dimorphisms in nasal parameters were significant.

Analysis of solar chimney power plant utilizing chimney discrete model

The paper presents a mathematical thermal model for steady state airflow inside a solar chimney power plant using modified Bernoulli equation with buoyancy effect and ideal gas equation. The study evaluates the use of constant density assumption across the solar chimney and compares it with more realistic chimney mathematical discrete model that allows density variation across the chimney. The result shows that using a constant density assumption through the solar chimney can simplify the analytical model however it over predicts the power generation. The results show that the chimney height, the collector radius, the solar irradiance, and the turbine head are essential parameters for the design of solar chimneys. The maximum power generation depends on the turbine head and the relation is not monotonic.

Reformatted Computed Tomography to Assess the Internal Nasal Valve and Association With Physical Examination

To assess the cross-sectional area and angle of the internal nasal valve more accurately by reformatting computed tomography (CT) scans of the nasal airway according to a more appropriate orientation than scans traditionally sectioned in the coronal plane and then to compare the results with clinical data on the nasal valve obtained from physical examination. We performed a retrospective review of the medical records of 24 rhinoplasty patients treated at a private practice facial plastic surgery office affiliated with a tertiary care university hospital. The patients had fine-cut (0.75-mm section) CT scans ordered for nasal airway obstruction or nasal valve compromise at the same institution. These patients were evaluated from January 1, 2000, through December 31, 2010. The previously acquired CT scans were reformatted to obtain sections through the internal nasal valve at a more appropriate orientation. The internal nasal valve cross-sectional area and valve angle were measured through a standardized section (1 cut immediately anterior to the head of the inferior turbinate) from the reformatted scans. The cross-sectional area was also measured through the same point on the traditionally oriented CT scan, and the values were compared. The results from each patient's scan were compared with data from the patient's medical record and analyzed against the patient's preoperative modified Cottle examination findings. The CT scans oriented in the reformatted plane through the internal nasal valve provided a narrower valve angle than the traditionally oriented CT scans and more closely approximated the hypothesized true value of the internal nasal valve of 10° to 15° (P < .001). In a comparison of the same-side internal nasal valve angle and cross-sectional nasal valve area between the 2 different CT scan orientations, a statistically significant difference in the internal nasal valve angles between the 2 scan orientations was discovered, but this finding did not reach significance when distinguishing the nasal valve cross-sectional area. Finally, no correlation was found with regard to the preoperative modified Cottle maneuver scores for the internal nasal valve angle and cross-sectional valve area values in either scan orientation. Precise preoperative evaluation of the internal nasal valve is critical to the workup for reconstruction or repair of problems that involve this area. Although tools such as acoustic rhinometry exist to evaluate the cross-sectional area of the nasal valve, many rhinoplasty surgeons do not have access to this expensive equipment. A CT scan with reformatting in the proper plane of the internal nasal valve can provide the surgeon with improved anatomical information to assess that region. With this in mind, however, the surgeon should always perform a thorough preoperative physical examination and treat the patient and his or her symptoms, not the imaging studies, when considering a candidate for a surgical intervention.

オイル殺菌装置 (Oilizer®) によるタービンヘッドの殺菌効果

オイル殺菌装置 (Oilizer®) によるタービンヘッドの殺菌効果

Correlation of Nasal Obstruction with Nasal Cross-Sectional Area Measured by Computed Tomography in Patients with Nasal Septal Deviation

The objective of the present study was to investigate the relationship between the subjective sensation of nasal obstruction and the corresponding cross-sectional area for nasal airflow in patients with a deviated septum. Seventy-one patients with a diagnosis of unilateral nasal obstruction due to a deviated nasal septum were evaluated by preoperative computed tomography. Anterior anatomic characteristics (the internal nasal valve angle and the cross-sectional areas at the external nasal valve, the head of the inferior turbinate, and the head of the middle turbinate) and posterior anatomic factors (the cross-sectional areas at the openings of the frontal sinus, maxillary sinus, and end of the nasal septum) were examined. Associations between the computed tomography measurements and the subjective severity of nasal obstruction were analyzed with a visual analog scale (VAS). Anterior and posterior anatomic characteristics were associated with the subjective severity of nasal obstruction. Anterior anatomic factors were related to the VAS scores of patients with anterior septal deviation, and posterior anatomic factors were related to the VAS scores of patients with posterior septal deviation. This study indicated that the anterior and posterior parts of the nasal cavity are both related to nasal obstruction. In some patients, the posterior part of the nasal cavity was more important than other locations in causing nasal obstruction.

하비갑개수술이 비강의 열/습도 전달 특성에 미친 영향

In addition to respiration, the nose performs three other major physiological functions-air-conditioning, filtering, and smelling. On the basis of our experience in experimental investigations of nasal airflows in normal and abnormal nasal cavity models, airflows in the normal model and three artificially deformed models, which simulate the results of surgical treatments (inferior turbinectomy), are investigated by PIV and CFD. The left cavities of all three models are normal, and the right cavities are modified as follows: (1) excision of the head of the inferior turbinate, (2) resection of the lower fifth of the inferior turbinate, and (3) resection of almost the entire inferior turbinate. The use of high-resolution CT data and careful surface rendering of three-dimensional computer models with the help of an ENT doctor provide more sophisticated nasal cavity models. Nasal airflows for both normal and deformed cases are also compared.

Effects of single-sided inferior turbinectomy on nasal function and airflow characteristics

Knowledge of airflow characteristics in the nasal cavity is essential to understanding the physiologic and pathologic aspects of nasal breathing. Airflows inside post-surgery models were investigated both experimentally and numerically to simulate the inferior turbinectomy. The left cavities of all three models are normal and right cavity is modified by (1) excision of the head of the inferior turbinate, (2) resection of the lower fifth of the inferior turbinate, and (3) resection of almost the entire inferior turbinate. Thin-slice CT (computed tomography) data (0.6mm deep) and meticulous refinement of the model surface by over a decade-long collaboration between engineers and an experienced ENT doctor resulted in the creation of sophisticated nasal cavity models. After numerical experiments and validation by comparison with the PIV results, the CFD code using the Reynolds stress turbulent model and variable temperature boundary condition on the mucosal wall was chosen as the proper numerical framework. Both global quantities (pressure drop, flow rate ratio, total wall heat transfer) and local changes (velocity, temperature, humidity, pressure gradient, and wall shear stress) were numerically investigated. The turbinectomy obviously altered the main stream direction. The flow rate in the upper airway near the olfactory slit decreased in models (1) and (3). This may weaken the olfactory function of the nose. Fluid and thermal properties that are believed to be related with physiology and prognosis are dependent on turbinate resection volume, position, and manner. Widening of the inferior airway does not always result in decreased flow resistance or wall heat transfer. The gains and losses of inferior turbinectomy were considered by analysis of the post-surgery model results. Nasal resistance was increased in model (1) due to sudden airway expansion. Nasal resistance increased and the wall heat transfer decreased in model (3) due to sudden airway expansion and excessive reduction of the mucosal wall surface area. Local shear stress and pressure gradient levels were increased in models (1) and (3).

Septoplasty and decongestant improve distribution of nasal spray

This study prospectively examined the intranasal distribution of nasal spray after nasal septal correction and decongestant administration. A cohort of 20 patients was assessed for the distribution of nasal spray before and after nasal septum surgery. Sprays were dyed and administered one puff per nostril when patients hold their head up in an upright position. Before and after decongestant administration, the intranasal distribution was semi-quantitatively determined by nasal endoscopy. The results showed that the dyed drug was preferentially sprayed onto the nasal vestibule, the head of the inferior turbinate, the anterior part of septum and nasal floor. As far as the anterior-inferior segment of the nasal cavity was concerned, the distribution was found to be influenced neither by the decongestant nor by the surgery (P>0.05). However, both the decongestant and surgery expanded the distribution to the anatomical structures in the superior and posterior nasal cavity such as olfactory fissure, middle turbinate head and middle nasal meatus. No distribution was observed in the sphenoethmoidal recess, posterior septum, tail of inferior turbinate and nasopharynx. It was concluded that nasal septum surgery and decongestant administration significantly improves nasal spray distribution in the nasal cavity.

Mixed-flow vertical tubular hydraulic turbine: determination of proper design duty point

A new vertical single-regulated mixed-flow turbine with conical guide apparatus and without spiral casing is presented in this paper. Runner blades are fixed to the hub and runner band and resemble to the Francis type runner of extremely high specific speed. Due to lack of information and guidelines for the design of a new turbine, a theoretical model was developed in order to determinate the design duty point, i.e. to determine the optimum narrow operation range of the turbine. It is not necessary to know the kinematic conditions at the runner inlet, but only general information on the geometry of turbine flow-passage, meridional contour of the runner and blading, the number of blades and the turbine speed of rotation. The model is based on the integral tangential lift coefficient, which is the average value over the entire runner blading. The results are calculated for the lift coefficient 0.5 and 0.6, for the flow coefficient range from 0.2 to 0.36, for the number of the blades between 5 and 13, and are finally presented in the Cordier diagram (specific speed vs. specific diameter). Calculated results of the turbine optimum operation in Cordier diagram correspond very well to the adequate area of Kaplan turbines with medium and low specific speed and extends into the area of Francis turbines with high specific speed. Presented model clearly highlights the parameters that affect specific load of the runner blade row and therefore the optimum turbine operation (discharge—turbine head). The presented method is not limited to a specific reaction type of the hydraulic turbine. The method can therefore be applied to a wide range from mixed-flow (radial-axial) turbines to the axial turbines. Applicability of the method may be considered as a tool in the first stage of the turbine design i.e. when designing the meridional geometry and selecting the number of blades according to calculated operating point. Geometric and energy parameters are generally defined to an extent that these parameters are considered in detailed design using turbulent viscous flow CFD solver.

Numerical simulation study on effects of ambient temperature on airflow in the nasal cavity

To study the aerodynamics of the normal human nasal cavity under different ambient temperatures. Based on CT scanning, a model of a healthy adult's nasal cavity was established using computational fluid dynamics software from Fluent. Airflow in this model was simulated and calculated at ambient temperatures of 0 °C, 24 °C, and 37 °C during periodic breathing. Ambient temperature only had an impact on the temperature in the nasal cavity during the inspiratory phase, and the temperature distribution was not symmetrical in the inspiratory acceleration and deceleration phases. The ambient temperature significantly affected airflow speed in main nasal passages during the inspiratory process, but had little impact on flow status (proportion and streamline of airflow in different nasal passages). Temperature differences increased the irregular air movement within sinuses. The anterior nasal segment, including the area between the valve and the head of the middle turbinate, was the most effective part of the nasal airway in heating the ambient air. Our findings describe the effects of ambient temperature on airflow parameters in the nasal cavity within a single respiratory cycle. This data is more comprehensively and accurately to determine the relationship between nasal cavity aerodynamics and physiological functions.

Revison endonasal dacryocystorhinostomies: analysis of 44 procedures

To determine the success rate of revision endoscopic dacryocystorhinostomies (DCR) and to analyse 44 revision DCRs. The operative and postoperative data were collected in 44 revision DCRs. The corrections of associated structural anatomic alterations were performed during the surgery (resection of the scarr, the bone window creating, resection of the head of the middle turbinate, septoplasty, ethmoidectomy etc.) and the intubation was performed in all cases. The follow-up interval ranged from 12 to 36 months. The 44 ReEDCRs were performed in adults and there were only 5 children under the age of 15. The surgery was performed under local or general anaesthesia. The most frequent secondary procedures were scar resections, creating a wider bone window, and partial middle turbinate resection. Four patients were excluded for their follow-up periods had not been completed. An average time of the tubes removal was 5.6 months. The total success rate was 84.0%; the success rate was 85.7% in the group with closed rhinostomy and 1/2 in the group of canalicular and rhinostomy obstructions. The endonasal revision DCR is a safe and very effective surgical procedure following the failed DCRs. The correction of associated structural anatomic alterations that may be involved in the failure of previous surgeries can be easily performed.

Does nasal obstruction affect the articulation of plosive consonants?

In this study, we investigated the impact of chronic nasal obstruction on articulation of the Turkish voiceless plosive (stop) consonants and examined the effect of the nose- and mouth-breathing on the articulatory characteristics of the specific speech sounds. Twenty-one controls with nose-breathing and 20 patients with mouth breathing were included in this study. The nasal obstruction history of the patients was 10 to 22 years. In the mouth-breather group, intranasal pathologies except septal deviation and turbinate hypertrophy were excluded. The nose-breather subjects without nasal pathologies served as the control group. The subjects graded nasal obstruction through visual analog scale (VAS) from 0 to 10. The minimal cross-sectional area (MCA) and minimal cross-sectional volume (MCV) at the level of septal tubercle and the head of inferior turbinate were established to be 1 and 2 by acoustic rhinometry. Minimal cross-sectional volume was defined as the volume below the curve. The syllables [pa], [ta], [ka] uttered by the subjects were recorded for the spectrographic analysis. Voice onset time (VOT) was measured on wide-band spectrogram. The VOT value of /p/ was found lower and the VOT values for /t/ and /k/ were found higher in mouth-breathers compared to nose-breathers, while the difference was not statistically significant. The right and left-sided VAS values of the nasal obstruction group were significantly higher compared to controls (p=0.001). The right and left-sided MCA1, MCA2, MCV1 and MCV2 were found statistically different between the two groups. It was concluded that the articulation features of plosive consonants were not significantly affected by nasal obstruction.

Design of the rotor blades of a mini hydraulic bulb-turbine

The rotor blades of a mini hydraulic turbine were designed using a quasi-three-dimensional method. The meridional flow is computed by a streamline curvature method and the blade-to-blade flow by a singularity method. The rotor blade sections are the NACA 66 (MOD) with a = 0.8 meanline. The camber and the stagger angle of the blade sections are adjusted to fulfil the prescribed angular momentum distributions, at the rotor inlet and outlet sections, and zero-incidence flow angle, at the blade leading edge. Turbine head and efficiency versus flow rate curves were obtained for different rotor blade stagger angles at constant rotational speed. Radial distributions of time-averaged velocity and pressure, measured at the rotor exit section with a five-hole probe, are also presented. The design and the experimental results are compared with three-dimensional inviscid flow numerical results computed by the FLUENT code. The domain is discretized by unstructured meshes with a maximum of 2.5 × 10 6 elements. The numerical results show good agreement with the design values and the experimental results, validating the design hypothesis of small radial velocity in the flow through the rotor.

Comparative investigations of anatomy and physiology in mammalian noses (Homo sapiens--Artiodactyla)

Background: Knowledge of airflow in animal noses is sparse. Such knowledge could be important for selection of animal models used in environmental studies. From the phylogenetic and ontogenetic point of view, a comparison between the animal and human nose is interesting. Method: Nose models of 5 even-toed ungulate species (he-goat, sheep, cow, roebuck, wild boar) and two humans (new born infant and adult) were examined. Anatomical and physiological features of the nasal cavities of all species were compared. All models were rinsed with water and the flow was visualized for observation. Geometric and rhinoresistometric measurements were then performed. Results and conclusions: Even-toed ungulates have two turbinates directly in the main part of the nasal airflow (respiratory turbinates) and a different number of turbinates in a so-called dead space of the nasal airflow above the nasopharyngeal duct (ethmoidal turbinates). The latter correspond with the upper and middle turbinate in analogy to the human nose. Respiratory turbinates of even-toed ungulates insert immediately behind the external nasal ostium. Thus, the whole nasal cavity acts as a functional area with the exception of a small area acting as dead space only detectable in ruminants, possibly indicating a small evolutionary progress from suinae to bovidae. The shape of the animal nasal cavity is stretched and flat. The airflow runs nearly completely turbulent through the nose. The nasal cavity in the adult human is relatively short and high. The area between the external nasal ostium and the head of the inferior turbinate is called inflow area. It distributes the airflow over the whole nasal cross section and generates a turbulent flow. So the airflow is prepared to contact the mucosa in the functional area (turbinate area). The morphology of the inflow area is approximately formed by the shape of the external nose. The nasal cavity of a newborn child is also stretched and flat and more similar to the nasal shape of the investigated animals. The inflow area in the newborn nose is not yet developed and corresponds with the growing external newborn nose. One can hypothesize that the inflow area in human noses is a morphological adaptation in the changed length-height-ratio of the nasal cavity.

Comparative investigations of anatomy and physiology in mammalian noses (Homo sapiens--Artiodactyla)

Knowledge of airflow in animal noses is sparse. Such knowledge could be important for selection of animal models used in environmental studies. From the phylogenetic and ontogenetic point of view, a comparison between the animal and human nose is interesting. Nose models of 5 even-toed ungulate species (he-goat, sheep, cow, roebuck, wild boar) and two humans (new born infant and adult) were examined. Anatomical and physiological features of the nasal cavities of all species were compared. All models were rinsed with water and the flow was visualized for observation. Geometric and rhinoresistometric measurements were then performed. Even-toed ungulates have two turbinates directly in the main part of the nasal airflow (respiratory turbinates) and a different number of turbinates in a so-called dead space of the nasal airflow above the nasopharyngeal duct (ethmoidal turbinates). The latter correspond with the upper and middle turbinate in analogy to the human nose. Respiratory turbinates of even-toed ungulates insert immediately behind the external nasal ostium. Thus, the whole nasal cavity acts as a functional area with the exception of a small area acting as dead space only detectable in ruminants, possibly indicating a small evolutionary progress from suinae to bovidae. The shape of the animal nasal cavity is stretched and flat. The airflow runs nearly completely turbulent through the nose. The nasal cavity in the adult human is relatively short and high. The area between the external nasal ostium and the head of the inferior turbinate is called inflow area. It distributes the airflow over the whole nasal cross section and generates a turbulent flow. So the airflow is prepared to contact the mucosa in the functional area (turbinate area). The morphology of the inflow area is approximately formed by the shape of the external nose. The nasal cavity of a newborn child is also stretched and flat and more similar to the nasal shape of the investigated animals. The inflow area in the newborn nose is not yet developed and corresponds with the growing external newborn nose. One can hypothesize that the inflow area in human noses is a morphological adaptation in the changed length-height-ratio of the nasal cavity.

Multi-megawatt offshore wave energy converters – electrical system configuration and generator control strategy

Considerations of the electrical system configuration and the control strategy for the wave dragon (WD) multi-megawatt (MW) offshore wave energy converter (WEC) are presented in this study. The electrical system consists of 16–20 turbine–generator–AC/DC/AC converter units. The characteristics of the low-head water-turbine and generator control strategy enabling maximum energy capture and the best performance for the MW offshore wave energy power take-off system are described in detail. Simulation results from a single turbine–generator–frequency converter unit at different turbine heads are presented at the end of the study.

Aerodynamic effects of inferior turbinate surgery on nasal airflow--a computational fluid dynamics model

Turbinate reduction surgery may be indicated for inferior turbinate enlargement when conservative treatment fails. The aim of this study was to evaluate the effects of inferior turbinate surgery on nasal aerodynamics using computational fluid dynamics (CFD) simulations. CFD simulations were performed for the normal nose, enlarged inferior turbinate and following three surgical procedures: (1) resection of the lower third free edge of the inferior turbinate, (2) excision of the head of the inferior turbinate and (3) radical inferior turbinate resection. The models were constructed from MRI scans of a healthy human subject and a turbulent flow model was used for the numerical simulation. The consequences of the three turbinate surgeries were compared with originally healthy nasal model as well as the one with severe nasal obstruction. In the normal nose, the bulk of streamlines traversed the common meatus adjacent to the inferior and middle turbinate in a relatively vortex free flow. When the inferior turbinate was enlarged, the streamlines were directed superiorly at higher velocity and increased wall shear stress in the nasopharynx. Of the three surgical techniques simulated, wall shear stress and intranasal pressures achieved near-normal levels after resection of the lower third. In addition, airflow streamlines and turbulence improved although it did not return to normal conditions. As expected, radical turbinate resection resulted in intra-nasal aerodynamics of atrophic rhinitis demonstrated in previous CFD studies. There is little evidence that inspired air is appropriately conditioned following radical turbinate surgery. Partial reduction of the hypertropic turbinate results in improved nasal aerodynamics, which was most evident following resection of the lower third. The results were based on a single individual and cannot be generalised without similar studies in other subjects.

Beeinflusst die Resektion der mittleren "Turbinate" (Concha) die Erfolgsrate der endonasalen Dacryocystorhinostomie?

BACKGROUND: To evaluate if the partial resection of the head of the middle turbinate increases a patency of the rhinostomy in the primary endonasal dacryocystorhinostomies (EDCR). METHODS: The definite evidence-based determination of the relative efficacy of partial turbinectomy on EDCR has not been established in the literature so far. The partial middle turbinate resection is performed during EDCRs in patients with the anteriorly enlarged middle turbinate or in whom the lacrimal sac projection on the lateral nasal wall is covered with the anteriorly located head of the middle turbinate to prevent rhinostomy closure. The data were retrospectivelly collected in 639 primary EDCRs performed in the patients over 16 years old in the period 1994–2008. Only the patients with subsaccal nasolacrimal duct obstructions were involved in the study (233 cases); the patients with canalicular obstructions and secondary surgical procedures (silicone intubation, Mitomycin C, ethmoidectomy, septoplasty) were excluded. The success rates of patients with the partial middle turbinate resection (group I) and without resection (group II) were compared one year after the surgery. RESULTS: The overall success rate was 217/233 (93.1%) in EDCRs with/without partial turbinate resections. In group I the success rate was 96/99 (96.9%), in group II 121/134 (90.3%). The differences between the results in groups I and II were statistically significant (p < 0.05). CONCLUSIONS: The partial middle turbinate resection significantly improves the success rate in the primary EDCRs.