Hinge Flap Research Articles

Effects of structural nonlinearities on flutter characteristics of the CF-18 aircraft

The describing function method is used to analyze the flutter characteristics of the CF-18 aircraft with structural nonlinearities. The first nonlinearity studied is located at the CF-18 wing-fold hinge. From ground test data, this hinge can be represented by a bilinear spring. A flutter sensitivity study is carried out, which shows that when the hinge stiffness is reduced, divergent flutter involving the wing bending and torsion modes is replaced by limit-cycle flutter of the wing torsion and outer wing rotation modes. Another form of nonlinearity at the outboard leading-edge flap is also studied by treating it as a spring with free-play. Limit-cycle oscillations are possible only within a small range of velocities in the vicinity of its linear flutter velocity. The flutter modes remain unchanged and their frequencies are practically constant for hinge-stiffness values ranging from a few percent to its nominal value. Positive aileron angles are found to be more effective in alleviating limit-cycle flutter at the wing-fold than negative angles. Similar observations are made at the outboard leading-edge flap hinge where downward deflection of the aileron gives larger values of the preload and, hence, the equivalent stiffness than upward deflection.

Energy head implications of the installation of circular flap gates on drainage outfalls

A programme of experimental study on simple circular single hinged flap gates is reported. Energy losses resulting from the flow constriction created are found to be largely dependent upon the flow...

The hinged digit flap with dual W-plasties.

A U-shaped flap, hinged proximally and incised distally, adapts well on digits. When incising over joint skin, dual-running W-plasties are mandatory to prevent cicatricial bridging and functional compromise. In a series of 18 cases, no untoward difficulties have been noted.

Surgical Treatment of Laryngotracheal Stenosis by a Trough Technique

Many methods have been tried and reported in the treatment of laryngotracheal stenosis. Among them, a trough technique seems universal at present. To date, we have tried several methods of this technique, but each method had its own demerits. We used, as a cartilagenous framework, a homograft or tracheal ring cartilages for the last four cases of laryngotracheal stenosis. These tracheal ring cartilages were resected from relatively young patients with laryngeal carcinoma. Total laryngectomy was done just below the level of the fourth tracheal ring, then the fourth tracheal ring was resected and stored in 70% alcohol. The cartilage was used after it was made certain pathologically that there was no invasion of carcinoma at the third tracheal ring level. The operative procedure of this trough technique is as follows. In the first stage, a trough is created at the stenosed region and the trough is maintained by placing a Quick Set Silicone (Q.S.S.) stent mold over it. While waiting for scar formation of the tissues surrounding the trachea, the second stage reconstruction is performed four weeks after the first. The trough is closed with hinged skin flaps on both sides, and the reserved tracheal ring cartilages are sutured every 5 mm onto the outer surface of the hinged skin flaps to make a cartilagenous framework. The neck is closed with advanced neck skin flaps. A more ideal tracheal lumen is created by this technique. Our four patients are doing well two years or more after the operation.

Semi-Single Reconstruction of the Hypopharynx

In treating hypopharyngeal carcinoma T3N3M0, semi-single reconstruction was carried out after laryngopharyngoesophagectomy, using a pectoralis major myocutaneous flap. Procedurally, the hypopharynx was not closed, but a small fistula was made. After post-operative radiation therapy, the fistula was closed using a local hinge flap and a rotation flap under local anesthesia. As advantages of this method, it may be pointed out that major complication due to salivary leakage is absent; the fistula can be closed under local anesthesia; and no influence is exerted on post-operative radiation therapy.

An exploratory study of area-efficient vortex flap concepts

The potential of planform modification and hinge-line relocation to improve the thrust efficiency of vortex flaps was experimentally investigated on a 60-deg cropped delta wing model. Spanwise segmentation of the flap, together with chord-tailoring of the segments, allowed the vortex to be maintained on the outboard flap surfaces to higher angles of attack. In addition, location of the flap hinge aft of and underneath the wing leading edge generated substantial thrust from the vortex suction acting on the leading-edge lower surface. A combination of these beneficial effects allowed the flap/wing area to be reduced from 11.4 percent of the continuous flap to 6.3 percent of segmented flap, essentially without detriment to the incremental lift-to-drag ratio due to flap addition in the lift coefficient range 0.5-0.7 based on the basic wing area.

Carcinoma of the hypopharynx and cervical esophagus--a retrospective investigation of 67 patients.

A retrospective review of 67 patients of carcinoma of the hypopharynx and cervical esophagus treated at Kurume University Hospital from 1971 to 1980 was completed. Fifty-four patients underwent curative treatments and 13 were subjected to palliative treatments. The results of this retrospective studies are summarized as follows: (1) In the 54 patients of curative treatments, 3- and 5-year cumulative survival rates calculated by the actuarial method were 39.0% and 25.4%, respectively. (2) The more advanced the disease was, the lower the survival rate. (3) Of 35 deaths in the curative treatment group, the cause of death was primary lesion in 4, neck metastasis in 8, distant metastasis in 8, surgery in 5, complication in 6, unknown in 1 and intercurrent disease in 4. (4) Pre-operative radiation did not result in improvement in the survival rate. (5) Application of Bleomycin did not reduce the development of distant metastasis. (6) With respect to reconstruction of the food channel, the technique which employed a secondary procedure with the use of hinge flap and DP flap yielded the best results.

Surgical closure of palatal fistulae: follow-up of 84 personally treated cases.

In a series of 84 personally operated palatal fistula (83 in cleft patients) over a 5-year-period, anatomic and/or physiologic closure was achieved in 82%. Minor recurrences occurred in 13%, and 4% were (total) failures. The age at operation varied from 2 years 10 months to 55 years. In nine recurrences (11%) definitive closure is still planned but postponed to the postpubertal period. 75% of the patients were operated on by the author once only, 14% twice, while in 11% three or more operations were necessary. The routine operative methods have been the double hinge flap and the bone grafting procedure. Other techniques have been used only rarely, and with specific indications.

Examination of the flap-lag stability of rigid articulated rotor blades

A critical examination of flap-lag stability of a centrally hinged, spring-restrained rigid blade in both hover and forward flight is presented. Several differences in the equations of motion for blade flap-lag stability in the existing literature are identified. A rigorous and systematic development of these equations for a rigid articulated blade in forward flight shows the existence of some linear aerodynamic coupling terms associated with blade steady-state flapping and lagging in the perturbation equations. The differences identified are shown to be associated with whether or not the lag hinge flaps with the blade. The implications of these differences on stability are examined, and it is shown that the pitch-lag coupling terms associated with a hinge arrangement in which the lag hinge flaps with the blade have a marked influence on flap-lag stability, depending on the system parameters.

Lifting-surface theory applied to ship-rudder systems

In this paper a ship-rudder system is considered as a low-aspect-ratio wing with a hinged flap. The model is restricted to single-rudder ships in deep water. A lifting-surface theory is used to compute the lateral forces on the ship caused by a rudder deflection. Attention is paid to the influence of the rudder's length and height. The results are compared with those from slender-wing theory.

RANDOM WAVE SIGNAL GENERATION BY MINICOMPUTER

The computer programmed implementation of a pseudorandom noise generator based on the use of a binary feedback shift register and an associated digital filter is described. Descriptive details are given for the compensation of the filter for the various dynamic transfer functions in the system. The random signal generator has been programmed both for a dedicated computer (NOVA 1200 with 4K core) which can carry up to 50 different spectra in core at any one time and for the EAI 64 0 with 16K core and disc storage which was used to investigate the spectral and statistical properties of the generated wave. JONSWAP spectra with 0.6 and 1.0 Herz centre frequencies were generated and observed at locations from 5 to 40 meters from the wave maker using a hydraulically operated machine in a partial piston and partial hinged flap mode m 0.9 meter of water. Measurements indicate that JONSWAP spectra can be closely matched in the flume. The 1.0 Herz spectrum is less stable as a function of distance, all spectra indicate a significant decrease of the spectral peak as a function of distance from the wave maker and the ratio of ^xaax/^av ls ln general larger than that observed by Wiegel and Kukk.

Prevention of airborne contamination and cross-contamination in germ-free mice by laminar flow.

The efficacy of horizontal and vertical laminar flow units (equipped with high-efficiency air filters) in the prevention of cross-contamination between cages and of contamination from outside has been demonstrated. With germ-free mice and using germ-free standard techniques for sterilization and for the transfer of germ-free mice into the cabinets via a standard entry lock, it was found that during an observation period of 2 weeks the animals remain ;negative'. Other experiments were performed with equally good results in cabinets equipped with a hinged flap, closing 95% of the open front side. When the flap was closed the air flow could be reduced accordingly, thus reducing the noise level and the risk of dehydration.Experiments made with germ-free mice in a ;down-flow unit' were also invariably good.In another type of experiment, cages with conventional mice were placed in the cabinets between cages with germ-free animals at varying distances. If all animals were maintained on wire mesh (to minimize the aerosol production of dust) and if the ;conventional' cages were at a distance of 10 cm. from ;germ-free cages' the latter remained bacteria-free during test periods of one week.The use of ;laminar flow isolators' for the isolation of human patients is mentioned.

A double, overlapping hinge flap to close palatal fistula.

After a brief survey of the methods of closing palatal fistulas, a new operative method is presented. This method makes it possible to close relatively easily fistulas up to a diameter of 2 cm in a one-stage operation. The method is simple and has also proved reliable.

Pericranial Hinged Flap for Congenital Posterior Meningoencephalocele Closure


 
 
 
 Background: Posterior meningoencephalocele is a complicated case that requires adequate method for closure of the defect. Congenital meningoencephalocele is a rare incidence estimated at 1:3000 to 10000 live births; with occipital encephaloceles are the most common. The method for closure should prevent leakage of cerebrospinal fluid (CSF) and coverage for the calvarial bone. Meningoencephalocele are treated by excising the non-functional brain tissue and closed the defect using thick connective tissue graft, alloplastic material and local flaps. The problems with closure are continuous leakage of cerebrospinal fluid and infection, especially when alloplastic material is used. In this case report, a pericranial flap is used to close the dura.
 Patient and Method: A neonate with occipital meningoencephalocele was consulted to the Plastic Surgery Department with wound dehiscence and recurrent herniation of brain tissue after undergoing first surgery by the neurosurgery team. On the second operation, a premilene mesh was placed which was later infected and causing wound dehiscence. We then close the defect using pericranial hinged flap and primary closure of the skin and subcutaneous tissue.
 Result: After the closure using pericranial hinged flap, there were no signs of infection and no CSF leakage. In 4 month follow up, the defect has completely healed.
 Summary: Closure of calvarial bone defect with pericranial-hinged flap provides a tight closure of the intracranial space, without increased risk of infection. Pericranial hinged flap should be considered as a method of choice for closure of intracranial defect, preventing leakage of cerebrospinal fluid and reducing risk of infection. 
 
 
 

Month in the Patent Office

In an aircraft having high‐taper low‐aspect ratio wings, in the preferred embodiment having a sweep‐back of 45 degrees means to reduce the induced drag by increasing the lift at the tips of the wings comprises hinged flaps 7 which occupy one‐third of each wing span outboard of the ailerons 6 and conventional flaps 5. A duct 21 having a rearwardly directed slotted orifice is positioned in each wing to blow high pressure gas over the upper surface of each flap when deflected to increase the lift. The gas is tapped from a gas turbine power plant 3 through a valve 18 and conduits 17 and 19 and a branch tapping through a valve 24 is shown applied to the flaps 5. Mechanism is provided whereby the flaps 7 may be operated in unison to increase lift at the outer portions of the wings or differentially in conjunction with the ailerons 6 to increase their rolling power. In FIG. 2 (not shown) the duct 21 and conduit 19 are shown as an integral unit forming part of the wing surface.

Aerodynamic forces on an oscillating aerofoil fitted with a spoiler

A thin aerofoil performing small harmonic oscillations in an incompressible fluid with flow separation from a prescribed point on the upper surface is the object of a theoretical investigation made in the paper. Two vortex sheets trail downstream, one from the trailing edge and the other from the point of flow separation on the upper surface. The flow separation may be caused by a spoiler or a flap hinge, or by having the aerofoil at incidence. If the incidence is high enough the flow will separate from the leading edge on the upper surface, and the theory includes this limiting case. The separation point is assumed to be fixed during the oscillation, and the pressure on the free streamlines is taken to be constant. Thus the free streamlines enclose a ‘dead-air’ region, which extends downstream as an infinite wake, just as in the Helmholtz model for steady flow. Formulae for the pressure distribution, lift and moment are obtained, and the effect of flow separation on the 'damping’ derivatives is illustrated in a number of graphs. On the whole it is found that a stalled or partially stalled aerofoil has less aerodynamic damping than an unstalled aerofoil.

The lift coefficient of a thin, jet-flapped wing

A solution is given for the inviscid, incompressible flow past a thin, two-dimensional wing at a small incidenceα, at the trailing edge of which a thin jet emerges at a small deflexionז. The flow inside the jet is assumed to be irrotational, and bounded by vortex sheets across which it is prevented from mixing with the main stream. The effect of the jet on the outside flow is the same as that of a vortex sheet of strength proportional to its curvature and to the jet momentum flux, together with a doublet distribution proportional to the jet thickness (and vanishing in the present limiting case). An integral equation is obtained for the slope of the jet, by aligning the trailing vortex sheet in the undisturbed-stream direction. The solution is expressed as the sum of a Fourier series, together with a function possessing the correct (i. e. logarithmic) form of singular behaviour at the trailing edge. The coefficients of a 9-term interpolation to the series have been calculated on an electronic computer, for a number of momentum-flux coefficientsCJlying between 0.01 and 10. The convergence is sufficient to justify the truncation of the Fourier seriesa posteriori. Simple expressions have been obtained for lift, pressure distribution and pitching moment. In particular, the lift coefficient is given byCL= 4πA0τ+ 2π(1+ 2B0)α, whereA0andB0are the leading Fourier coefficients associated with deflexion and incidence respectively. Close interpolations to their values are provided by the formulae 4πA0= 3.54C½J+ 0.325CJ+ 0.156C3/2J, 4πB0= 1.152C½J+ 1.106CJ+ 0.051C3/2J. For smallCJthese exhibit the dependence onC½Jwhich has been predicted by the empirical theories of Stratford (1956) and Woods (1955). Close agreement with the theory is found in tests made at the National Gas Turbine Establishment, Pyestock, by Dimmock (1955) on an 8:1 elliptic cylinder with a narrow deflected jet exit close to its trailing edge, both forτ≑ 30° and forτ≑ 60°. The measured lift coefficients lie within 5% of the corresponding calculated curves (an allowance of 12½% having been made for thickness), and the observed centres of lift lie within 2% of the chord of those calculated for a thin aerofoil, over the whole range ofCJ. The ‘shallow jet’ approxi­mations used in the theory had not been expected to apply forτas large as 60°, but the experimental agreement still found in this case resembles that obtained at large deflexion angles by the Glauert (1927) small angle theory for hinged flaps, in which similar approxima­tions occur.

The Estimation of Aerofoil Lifting Characteristics

THE lift coefficient of an aerofoil fitted with a hinged control flap and a tab can be expressed in the form:

Lobectomy for central abscess of lobe; hinge flap for multiple bronchopleural fistulas; post-tonsillectomy peripheral lung abscess: Report of 3 cases

CASE I. Lobectomy for central abscess of lobe. This patient was presented for the following special points of interest: 1. 1. An abscess of the central portion of the lobe without peripheral pleural reaction, which is present in the great majority of these cases; 2. 2. Practically no expectoration; 3. 3. Abscess cavities filled with debris resembling the material expressed from the crypts of chronically infected tonsils; 4. 4. Hemoptysis was the most important and urgent symptom; 5. 5. One-stage lobectomy resulted in a complete cure; 6. 6. A severe putrefactive, gas producing infection of the chest wall was controlled by the use of zinc peroxide. Case II. Hinge flap for multiple bronchopleural fistulas. 1. 1. The short duration of the pneumonia followed by empyema; 2. 2. The difficulty in making a differential diagnosis; 3. 3. The surgical problem of closing multiple bronchopleural fistulas; 4. 4. The use of a hinge flap which obviated the necessity of doing a radical thoracoplasty. CASE III. Post-tonsillectomy peripheral lung abscess. 1. 1. The production of a localized fetid empyema by rupture of a peripheral lung abscess; 2. 2. That eternal vigilance is necessary in looking for and detecting contralateral lesions as well as pocketing of the original infection; 3. 3. The rapidity with which a huge effusion is formed in the contralateral chest; 4. 4. The presence of a bilateral empyema with recovery.