Hinge Flap Research Articles

La fistule palatine ou vélaire dans les fentes

Palatal fistulas after primary closure of a cleft palate are extremely variable ranging from 15 to 35%. When they are symptomatic, these fistulas affect feeding (nasal regurgitation to liquids, discharge, bad smells) and phonation (hypernasality that can hinder the precise assessment of velar incompetence). First of all, it is important to analyze the cause of the fistula, it helps to avoid early recurrences. The correction must apply to respect the 2 mucosal planes (nasal mucosa and oral mucosa), the only guarantee of surgical success. Different techniques are usually described: lingual flap, lifting of all palatal mucosa, flap hinge, blaster, FAMM. In all cases, postoperative care plays a key role in the success of the surgical correction.

Using Sweeping Jets to Trim and Control a Tailless Aircraft Model

Active flow control (AFC) was incorporated into the Stability And Control CONfiguration model (SACCON) in order to trim it in pitch. The combination of AFC and traditional control surfaces enables the model to be stable and controllable. The model can be trimmed in pitch, provided that the significance of AFC is considered to be on par with other parameters affecting the aerodynamic characteristics of a wing. The most important outcome of this exercise implies that the traditional boundary-layer approach with inviscidly determined pressure distributions should no longer be used when AFC is to be implemented. This concept is proven by way of examples associated with the SACCON model that can be trimmed either by large deflection of flaps or by AFC. Proper combination of both parameters requires a minimal input of AFC (e.g., two actuators) in conjunction with a small flap deflection. Thus far, an actuator array located near the flap hinge was most effective but this result may not be universal. Tests were carried out at low speeds (i.e., at ) and Reynolds numbers based on the outer panel chord of the model that approached .

Reconstruction of Conchal Defect with Hinge Flap

Reconstruction of Conchal Defect with Hinge Flap

Two Cases of Septal Perforation Repair using Posterior Margin Based Hinge Flap

Two Cases of Septal Perforation Repair using Posterior Margin Based Hinge Flap

Gimbaled Tiltrotor Conversion Flight Loads Prediction Using Three-Dimensional Structural Analysis

This paper presents a method for modeling gimbaled rotor aeromechanics in Experimental 3D structural dynamics solver, which is a next-generation three-dimensional finite-element-based rotor structural dynamics solver. The rotor is modeled using a single blade with a free flap hinge at the hub, the motion of which is suppressed at integer multiples of the blade passage frequency by introducing harmonics of the joint rotation angle as additional trim variables, efficiently simulating gimbal kinematics. Rotor frequencies are examined for a three-bladed gimbaled rotor model and are found to combine the modes of both free flap hinge and fixed flap hinge (cantilevered) one-bladed models, similar to a teetering rotor, justifying the gimbal modeling methodology. Gimbal flapping is examined for a proprotor in edgewise flight: successful suppression of steady and 3/rev flapping indicates the gimbal model accurately represents the rotor kinematics. Air loads and blade loads are examined with and without with the gimbal model, revealing an increase in 3/rev sectional normal aerodynamic force on the blade but a decrease in the 3/rev flap and lag bending moment when the gimbal is added. Three-dimensional axial stress distribution at the blade root is examined, revealing only minor differences with and without the gimbal model, primarily in the flex beam.

Comparative Study between Bone Flap Insertion in Abdominal Wall Versus Flail Replacement in Decompressive Craniectomy of Acute Subdural Hematoma

AbstractBackground: Traumatic acute subdural hematoma remains one of the most lethal of all head injuries patients with Acute Subdural Hematomas (ASDHs) having higher mortality and lower functional recovery rates compared with those of other head-injured patients.Decompressive Craniectomy (DC) for management of ASDH with accompanying brain edema and midline shift has become one of the standard guidelines in many centers. DC remains to be the standard of surgical modality for patients with poor clinical status.Subcutaneous preservation of autologous bone flap is an inexpensive option that preserves the viability of the bone flap, resulting in good cosmetic results and the very low infection rate.Aim of Study: To compare results of (ASDHs) managed with DC with consequent subcutaneous bone flap insertion in the abdominal wall vs subcutaneous hinged flail placement in the craniectomy site.Patients and Methods: A retrospective review of 61 patients with (ASDHs) operated at the Department of Neuro-surgery, Cairo University and Beni Souf University Hospital during the period from Jan. 2012 – Dec. 2015. Patients were divided into:Group (A): 31 patients operated upon with subcutaneous abdominal bone flap insertion, (22 males and 9 females) median age was 42 years. On admission there were 19 patients with Glasgow Coma Score (GCS) below 8, and 12 patients with GCS 8 or above 8.Group (B): 30 patients operated upon with subcutaneous hinged flail bone flap replacement in the craniectomy site, (22 males and 8 females) median age 44 years. On admission there were 18 patients with GCS blew 8, and 12 patients with GCS 8 or above 8.Early surgical evacuation, dural fenestration, intensive care management to monitor intra cranial pressure and follow-up CT brain were done for all patients.Results: Group (A) 14 patients died in the hospital, 4 survived with unfavorable outcome (vegetative state), and 13 survived with favorable outcome.Group (B) 17 patients died in the hospital, 4 survived with unfavorable outcome (vegetative state), and 9 survived with favorable outcome.Conclusion: Analysis of the obtained data reveals that subcutaneous abdominal bone flap insertion shows a statisti-cally significant better prognosis as compared to subcutaneous hinged flail bone flap replacement at the craniectomy site which may be due to better decompression of the brain and allowing for more roomfor expansion.

Optimal performance of adaptive flap on flow separation control

The stall caused by flow separation of airfoil seriously compromises the efficiency and safety of wind turbines. Inspired by bird feathers, a passive flow control strategy was investigated by configuring adaptive flaps on the suction surface of the airfoil to delay flow separation. The Computational Fluid Dynamics (CFD) software ANSYS Fluent 17.0 using SST k–ω turbulence model was performed to study the performance of the adaptive flap with different length and location. The performance was evaluated by the comparison of total lift coefficient between the flap airfoil and clean airfoil. In addition, the performance of the double flaps configuration was investigated by Fluid-Solid Interaction (FSI) method. The results show that when the separation point is at the upstream of flap hinge point, the total lift coefficient increases with the flap rising, and when the flap reaches the optimal flap angle, the lift coefficient begins to decrease. When the flap operates in optimal angle, the closer the flap is to the trailing edge of the airfoil, the more the lift enhancement for moderate flow separation, and the closer the flap is to the leading edge of the airfoil, the more the lift enhancement for serious flow separation. For the flaps with the same location, the longer flap can block more backflow resulting in a better performance, but when the flap is long enough to block the fluid, the shorter flap has better performance. Considering the variations of the flap aerodynamic moment with the flap angle, an external hinge moment was recommended to improve the swinging flap performance.

“Flip-over flap” in two-stage cleft palate repair

PurposeThis study served to evaluate a two-stage concept in cleft palate repair, including key use of a triangular hinge (“flip-over”) flap, in order to prevent palatal fistulae. It uses data from a prospective registry established in 1991. Materials and methodsThe concept entails Furlow soft palate repair (at 1 year of age) and hard palate closure (at 4 years) by a three-pronged approach [paring of the edges with or without postero-lateral relaxing incisions, peninsula (Veau) flap(s)], plus a triangular hinge flap. The latter is elevated from the oral layer of the already-repaired soft palate, stays based anteriorly, and is flipped over to close the posterior nasal layer defect. The case series is compared with data from the literature. ResultsThe palatal fistula rate for Veau II to IV types (two-stage surgeries) was 4.3%. The overall fistula rate in the cleft population (Veau I–IV) was 2.9%. Meta-analyses describe 4.9 and 8.6% on average. There was no difference between sample A in which the flip-over flaps were used only when modified Veau flaps were indicated (until 2006) and sample B in which it was used regardless of the technique of hard palate closure applied (2006–2018). The fistula rate decreased to zero after 2010, which may reflect also an influence of other factors such as the interpositioning of a collagen membrane and also of improved surgical judgment. ConclusionsUsing a flip-over flap in two-stage cleft palate repair may contribute to prevent fistula formation at the hard/soft palate junction. Level of evidenceIII.

Mechanism/structure/aerodynamic multidisciplinary optimization of flexible high-lift devices for transport aircraft

Mission adaptive variable camber wing in both chord-wise and span-wise directions that can improve the aerodynamic performance during takeoff, landing and cruising flight, will be the state-of-the-art high-lift system for next generation airliners. Based on NASA TrapWing model released on the 1st AIAA CFD High-lift Prediction Workshop, a smart high-lift system with “Flexible Droop Nose & Single Slotted Hinge Flap combined with spoiler deflection & Flexible Trailing Edge Flap” is proposed in this paper. The Flexible Droop Nose is actuated by kinematic chains mechanism, the Single Slotted Hinge Flap is actuated by simple hinge mechanism and the Flexible Trailing Edge Flap is actuated by link/track mechanism.A mechanism/structure/aerodynamic multidisciplinary optimization platform based on iSIGHT software is constructed for this smart high-lift system. This platform consists of stress analysis, high-lift configuration generation, high-lift configuration structure grid generation, computational fluid dynamics and optimization algorithm modules. The optimal takeoff and landing configurations with comprehensive performance of mechanism, aerodynamic and structure is then obtained after multidisciplinary optimization. Finally, the CFD results show that the aerodynamics performance of this smart high-lift system is more effective than the original NASA TrapWing model.

Robust fluid-structure interaction analysis of an adaptive airfoil using shape memory alloy actuators

In the present paper, an aero-structure interaction model for the rapid simulation of morphing structures realized through shape memory alloy (SMA) actuators is presented. The aerodynamic simulation method implements a potential flow method strongly coupled with an integral boundary layer method in the context of a viscous-inviscid interaction approach, which includes a transition prediction model and a simplified shear stress-transport equation for the turbulence closure. The structural analysis model of the airfoil integrates a well-established SMA constitutive model for the prediction of the actuator behavior into finite element software. The two numerical models are loosely interconnected by exchanging geometrical and loading data at each iteration. An articulated 2-link adaptive mechanism for load alleviation purposes in horizontal axis wind turbine blades is investigated considering two different morphing scenarios: (1) operation of a single hinged flap; (2) combined movement of two sequential airfoil segments is attempted to achieve a smoother camber variation. The present fluid-structure interaction (FSI) model is employed with the aim to quantify its effect and benefits on the active shape control of the morphing airfoil, the actuator response, and the aerodynamic performance including lift and drag coefficients. The presented results demonstrate the robustness and numerical performance of the developed FSI method.

Use of Limberg flap double layered palatoplasty in the closure of acquired oro-nasal fistula in adults – A series of 7 cases with 6 months follow-up

ObjectiveOronasal fistula (ONF) is an abnormal communication between the oral and nasal cavity. It may arise in consequence to iatrogenic injury, neoplasms, trauma or following cleft palate repair. Closure of palatal fistula can be achieved by local and regional flaps. These procedures are often cumbersome and leave a raw nasal/oral surface which may increase the incidence of postoperative problems. The reported recurrence rate of the fistula is between 37% - 65%. The present paper demonstrates the versatility of the rhomboid flap in the closure of ONF in a two-layered fashion to avoid recurrence and donor site morbidity. MethodsSeven patients (male, 6; female, 1) underwent reconstruction with Limberg flap for traumatic oronasal fistula of size less than 15 mm in its greatest dimension. The mucoperiosteum was first elevated gently and inverted to close the nasal side as a hinged flap, followed by the Limberg rhomboid flap, raised from one corner of the defect to provide tension-free closure of the oral surface. ResultsThe fistula was completely closed in all cases at the first attempt, without any peri- operative complications. All fistulas successively healed, and none of our patients developed any significant postoperative bleeding, infection or fistula recurrence during the entire follow-up period of 6-9 months. ConclusionThis study elucidates that Limberg flap procedure can be performed for managing oronasal fistula with a low complication rate, short hospital stays, and good long-term results. It can be used as an alternative to the existing conventional techniques in the closure of ONF.

지상 및 비행 시험을 통한 플랩의 힌지 모멘트 추정

본 논문에서는 항공기 플랩 운용조건에 따라 변하는 플랩의 힌지 모멘트를 추정하는 실제적인 방법을 소개하였다. 플랩의 설계를 위하여 구조 하중해석과 풍동시험으로 산출한힌지 모멘트를 실제 비행 힌지 모멘트와 비교할 수 있었으며, 플랩 구조의 정적 안전성을 확인할 수 있었다. 이를 위해서 두 개의 변형률게이지를 플랩 힌지에 장착하였으며, 항공기 하중 모니터링 탑재장비를 사용하였다. 지상 시험을 통해서 힌지의 변형률과 모멘트의 상관관계를 해석해와 유한요소해석으로 교정하였다. 비행 시험에서는 플랩 처짐 각도 및 속도와 함께 변형률 신호를 기록하였다. 최종적으로, 계측한 변형률을 해석해와 유한요소해석으로 교정함으로서 비행 힌지 모멘트를 추정할 수 있었다.

Morphing airfoils analysis using dynamic meshing

PurposeThe purpose of this paper is to use dynamic meshing to perform CFD analyses of a NACA 0012 airfoil fitted with a morphing trailing edge (TE) flap when it undergoes static and time-dependent morphing. The steady CFD predictions of the original and morphing airfoils are validated against published data. The study also investigates an airfoil with a hinged TE flap for aerodynamic performance comparison. The study further extends to an unsteady CFD analysis of a dynamically morphing TE flap for proof-of-concept and also to realise its potential for future applications.Design/methodology/approachAn existing parametrization method was modified and implemented in a user-defined function (UDF) to perform dynamic meshing which is essential for morphing airfoil unsteady simulations. The results from the deformed mesh were verified to ensure the validity of the adopted mesh deformation method. ANSYS Fluent software was used to perform steady and unsteady analysis and the results were compared with computational predictions.FindingsSteady computational results are in good agreement with those from OpenFOAM for a non-morphing airfoil and for a morphed airfoil with a maximum TE deflection equal to 5 per cent of the chord. The results obtained by ANSYS Fluent show that an average of 6.5 per cent increase in lift-to-drag ratio is achieved, compared with a hinged flap airfoil with the same TE deflection. By using dynamic meshing, unsteady transient simulations reveal that the local flow field is influenced by the morphing motion.Originality/valueAn airfoil parametrisation method was modified to introduce time-dependent morphing and used to drive dynamic meshing through an in-house-developed UDF. The morphed airfoil’s superior aerodynamic performance was demonstrated in comparison with traditional hinged TE flap. A methodology was developed to perform unsteady transient analysis of a morphing airfoil at high angles of attack beyond stall and to compare with published data. Unsteady predictions have shown signs of rich flow features, paving the way for further research into the effects of a dynamic flap on the flow physics.

A Study of Multi-Objective Aerodynamic Optimization Design for Variable Camber Airfoils and High Lift Devices

Aiming at the synthetical optimization of the aerodynamic performance between the low-speed condition of two-dimensional high lift devices during take-off and landing phase and the high-speed condition of variable camber airfoil during cruise phase, an aerodynamic optimization design method for high lift device based on Kriging based surrogate model and multi-objective genetic algorithm has been developed. With the application of Adaptive Dropped Hinge Flap mechanism, the low-speed take-off and landing performance and high-speed cruise performance of the aircraft is improved by coupling deflection of the flap and spoiler. The position of flap hinge, deflection angle of spoiler and deflection angle of flap are taken as design variables; The Navier-Stokes equations are used to predict the aerodynamic forces of initial samples; The Kriging based surrogate model is employed to establish the algebraic relation between design variables and aerodynamic forces at take off, landing and cruise, obtaining four efficient prediction models for aerodynamic forces; Multi-objective optimization design with multi-objective genetic algorithm is conducted on the basis of surrogate models. The automatic generation of computational grid is achieved by the mesh deformation method based on RBF (Radial Basis Function) when the design variables change. On the basis of efficient global multi-objective optimization design platform, the synthetical optimization of high-speed and low-speed aerodynamic performance is conducted; The multi-objective solution set of the Pareto frontier is verified and analyzed, and the optimal solution with well matched high and low speed performance is selected.

Cyclic Blade Pitch Control Without a Swashplate for Small Helicopters

This paper presents the design, dynamical model, and experimental investigation of an articulated rotor that affords cyclic pitch authority in small unmanned air vehicle rotorcraft without requiring either a mechanical swashplate or blade pitch actuators. An offset flap hinge coincident with a skew lag-pitch hinge is used to impose a positive lag-pitch coupling on one rotor blade and a complementary negative lag-pitch coupling on the other. The motor torque driving the propeller is electronically modulated to excite a lead-lag motion with controlled rotational phase and amplitude; the ensuing once-per-revolution variation in blade pitch obtains the conventional control response and flapping character of fully actuated cyclic systems. The governing nondimensional lag-flap equations including a nonconstant speed hub are shown. The experimentally measured motor torque, the hub speed variation, the cyclic blade lag-pitch response, and the cyclic blade flapping response are compared with model predictions.

Hinge Flap with Triangular Extension for Reconstruction of Pharyngocutaneous and Laryngocutaneous Fistulas.

Hinge flaps are commonly used for closure of a pharyngocutaneous fistula (PCF) or laryngocutaneous fistula. These flaps are employed to augment the wall of the pharynx or larynx, but the junction between the reconstructed and native lumens can eventually become narrow and irregular after reconstruction with standard hinge flaps. We devised a method of adding a triangular extension to the end of either or both flaps and used it to treat 3 patients. In 1 patient who developed a PCF (4 × 10 cm) after laryngectomy followed by radiotherapy, the fistula was closed with 2 hinge flaps. One flap had a caudal triangular extension. The residual skin defect was covered by a pedicled latissimus dorsi musculocutaneous flap. Another patient who developed a PCF (2.5 × 3 cm) after laryngectomy underwent 2-stage reconstruction using a buccal mucosal graft with a triangular extension, followed by 2 hinge flaps. A patient who developed an laryngocutaneous fistula (1 × 2 cm) after radiotherapy and subsequent partial laryngectomy underwent reconstruction using 2 hinge flaps, each of which had a triangular extension. The skin defect was covered by another flap. Postoperative CT or video fluoroscopic examination of swallowing showed a smooth lumen with no strictures in all 3 patients. The triangular extension of the hinge flap supplements the pharyngeal/laryngeal wall at the junction between the reconstructed and intact regions, thus avoiding postoperative stricture. Especially with PCF reconstruction, restoration of a smooth luminal surface minimizes dysphagia.

Stable, Planar Self Propulsion Using a Hinged Flap

This paper discusses planar self-propelled motion of a primary body in water generated by using a hinged flap at its trailing edge. The coupled dynamic model incorporates unsteady loads based on Theodorsen’s unsteady lifting theory for sinusoidal flapping at a given reduced frequency and tailored for their application within the framework of the body motion. Numerical simulations and stability analysis are provided for an example based on the geometry of the saithe or pollock.

Closure of fistula of the hard palate with two layers of mucoperiosteum

ObjectiveOronasal fistula represents a functional problem, as it may result in nasal regurgitation of food and fluids and it also leads to hypernasal speech. Many methods have been proposed for its closure with a high recurrence rate. The aim of this study was to assess the efficacy of closure of hard palate fistula by two layers of mucoperiosteal flaps. MethodsEighteen patients with fistula of the hard palate were included. The fistula was repaired by two layers of mucoperiosteal flaps; the first layer was created from the mucoperiosteum surrounding the fistula as bilateral hinge flaps and the second layer was formed of a rotational flap based on the greater palatine artery. Pre- and postoperative clinical assessment was performed. ResultsThe etiology of fistulas was previous cleft palate repair in 13 patients, previous nasal septal surgery in 3 patients, and untreated sharp accidental trauma to the palate in 2 patients. All patients presented with nasal regurgitation and hypernasal speech. Complete closure of all fistulas was achieved at first attempt, with no recurrence through the follow up period. ConclusionsClosure of oronasal fistula by two layers of mucoperiosteal flaps is an effective method and it has neither complications nor recurrence.

Helicopter modelling and study of the accelerated rotor

This work presents a helicopter dynamic model that captures the fuselage vibrations for an accelerated main rotor. Some rotor parameters are modified with the purpose of study their impact on the rotorcraft. Being this, a tool that allows to predict vibrations on the helicopter. The rotorcraft model has been built up by using VehicleSim, software specialized in modelling mechanical systems composed by rigid bodies. The rotors are articulated, the main rotor takes into account flap, lag and feather degrees of freedom for each of the equispaced blades and their dynamic couplings. The dynamic performance and the control action are embedded in a single code, thereby VehicleSim does not require external connection to other software package. This generates some advantages such as to reduce the compilation time. The control methodology makes use of PID controllers (Proportional, Integral, Derivative), which allows to use VehicleSim commands exclusively. The state space matrices have been obtained in order to analysis the uncoupled main rotor flap and lag modes. The detection of vibrations from the offset flap hinge as well as the lag hinge are not straightforward tasks and this helicopter model provides an accurate tool to study these. A short time Fourier transform processing is used to analysis the vibrations and these have shown to agree with the expected behaviour.

Deltopectoral and Pectoralis Musculocutaneous Flap Technique for Cervical Esophageal Reconstruction after Free-Jejunal-Flap Necrosis.

Free jejunal transfer has a high success rate, but if vascular thrombosis occurs, the salvage of failing flap with reanastomosis is difficult. This study described a combined deltopectoral (DP) and pectoralis major musculocutaneous (PMMC) flap 2-step technique for cervical esophageal reconstruction after free-jejunal-flap necrosis. In step 1, the detection of free jejunal flap with the subsequent debridement of necrotic and infected tissue was followed by the construction of external fistula on the pharyngeal side with the hole in cervical skin and the construction of another external fistula on the esophageal side and tracheal stoma with a single or double DP flap. In step 2, after the primary healing of all wounds was confirmed, a wide hinge flap was elevated for reconstructing the posterior wall or full circumferential defect of cervical esophagus. PMMC flap harvested from either the left or right anterior chest wall was used for reconstructing the cervical surface defect or anterior pharyngeal wall. This technique was used for cervical esophageal reconstruction after free-jejunal-flap necrosis in 5 patients. Step 1 surgery was performed at an average of 10 days after primary-free-jejunal flap transfer. Oral intake was resumed in all cases at an average of 117 days after step 2 surgery. No complications including esophageal stricture were found during a 6-month follow-up period. Combined DP and PMMC flap technique was useful for cervical esophageal reconstruction after free-jejunal-flap necrosis and applicable to patients with the late detection of jejunal necrosis and surgical-site infection.