External Burning Research Articles

Wall Curvature Effects on External Burning in Supersonic Flow

The present work is based on the very ingenious models that the Billig school has produced and developed over the last two decades concerning combustion in the viscous mixing region along surfaces exposed to a supersonic external flow. Here two particular areas have been addressed. First, the strong wall curvature effect on enlargement of the set of possible heating parameters is shown. External burning on curved surfaces appears to be more promising possibility than that on straight walls. Second, for applications on curved surfaces, the most striking novelty in contrast to the straight wall cases, that is the necessity of reading the wall slope in terms of the integration variable has been solved. The use of boundary value problem codes to recognize the throat position on the wall and to obtain proper values of the parameters at the inflow station have proven to be very successful and useful

Propulsive Efficiency of Hypersonic External Burning

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.

Porosity Development during CO2 and Steam Activation in a Fluidized Bed Reactor

Steam- and CO2-activated carbons from a Spanish HV bituminous coal char were obtained at 800−900 °C in a batch laboratory scale fluidized bed reactor. The N2 and CO2 adsorption isotherms and scanning electron microscopy allow for sample characterization. The development of porosity upon activation, using a fluidized bed reactor, is different depending on the activating agent. A much better activation development is attained with steam. Thus, total micropore volume linearly increases with the activation degree, attaining an apparent specific surface area of 1150 m2/g at 50% burnoff for steam-activated carbons. Although CO2 activation also produces a linear increase vs burnoff, much lower pore volume values are obtained, reaching an equivalent specific surface area of only 800 m2/g at 50% burnoff. SEM analysis indicates that CO2 produces external burning of the carbon particles. This different behavior of CO2 and steam activation was also observed for several runs carried out with almond shell char. The exp...

Acute airway obstruction following facial scalding: differential diagnosis between a thermal and infective cause

A 16-month-old boy received a 6 per cent hot water scald to his face and chest. The child had been suffering from an upper respiratory tract infection for 10 days prior to the injury. However, as the child rapidly developed respiratory tract obstruction, a differential diagnosis between acute infective epiglottitis and thermal injury to the hypopharynx was required. In fact, the hot water had reached the epiglottis and the aryepiglottic folds causing significant damage, whilst sparing the tongue and mouth. The child was admitted to the intensive care unit, intubated and ventilated for 4 1 2 days. The external burns eventually healed spontaneously. This case report demonstrates the rare occurrence of a minor scalding injury resulting in significant obstruction to the upper airway. Of additional interest is the presence of pre-existing symptoms of an upper respiratory tract infection and the total absence of any signs of intraoral burning. These additional factors demonstrate the necessity for absolute vigilance in the management of any scald in the region of a child's mouth. Intubation can be life saving and should be considered in any case of scalding associated with increasing respiratory distress.

96/05229 Effect of fuel- and furnace-side parameters on the operation of fluidized-bed furnaces

In an enclosure, as all the air inflow is consumed in burning with the excess fuel, the internal fire enters the decay phase, and such process is said flame exhaust. The complicated multistage process from an initial fire growth up to a flame exhaust followed by an external burning is investigated by means of a Large-Eddy-Simulation (LES). Turbulent combustion process is modelled by an Eddy Break-Up concept by using two sequential, semi-global steps for CO prediction. The numerical model solves three dimensional, time-dependent Navier–Stokes equations, coupled with submodels for soot formation and thermal radiation transfer. The critical fuel supply rate needed for flame to exhaust and the time period from the fuel ignition to the appearance of an external flaming in medium-scale facilities are previously obtained experimentally by Chamchine AV, Graham TL, Makhviladze GM, et al. [Experimental studies of under-ventilated combustion in small and medium-scale enclosures. In: Proceedings of the fourth international seminar on fire and explosion hazards; 2003. p. 97–107.], and the general trends predicted by the numerical model follow closely their experimental observation. This model is capable of adequately describing the essential simultaneous phenomena (flame height, soot generation, CO production, convection and radiation) occurring in a room fire. The distinct transient stages of fire development prior to flame exhaust and scenarios of the exhaust are analysed. An external burning is followed after the flame exhaust inside enclosure, and the flame height, Hf, past the ceiling is approximately in an order of the opening height. Even though the flame exhaust takes place under the critical conditions, the heat transferred from the hotter gases and the external fire source poses significant threat to people inside enclosure, and potentially induces an ignition of fuel package exposed near the opening of an enclosure.

Eleven-year-old male with high-voltage electrical injury and premature ventricular contractions

We present a case of a boy with potential high-voltage electrical injury. The patient sustained electrical injuries after his kite became entangled in a high-power electrical line. He presented to the emergency department with minor external electrical burns and frequent premature ventricular contractions (PVCs). The patient's clinical course is outlined. A discussion of the epidemiology of high-voltage electrical injury in children and the clinical management of electrical-injury-induced cardiac complications is provided. Although cardiac abnormalities are found in a significant proportion of high-voltage electrical injuries, the vast majority are evident within 12 h, resolve spontaneously within a few days, and cause little or no long-term sequelae. A small proportion of normal children have clinically benign PVCs.

The transport of carbon monoxide from a burning compartment located on the side of a hallway

An experimental study was conducted to investigate the transport of high concentrations of carbon monoxide (CO) from a burning compartment located on the side of a hallway. Opening sizes of 0.04 and 0.12 m2 were used to vary the ability of the jet of fire products entering the hallway to entrain surrounding gases. By controlling the depth of the upper layer of oxygen-deficient combustion gases accumulated in the hallway during preflashover, the oxygen concentration of the gases entrained into the jet of fire products entering the hallway was varied. An increase in the upper-layer depth resulted in higher CO and UHC yields and lower CO2 yields. When the depth of the layer fell below the bottom of the opening, downstream CO yields were found to increase to levels equivalent to or greater than yields measured inside the compartment, with the highest yields measured in experiments with external burning. Using the external burning as a flow visualization tool, the gases were observed to be transported nonuniformly down the hallway when the burning compartment was on the side. The bulk flow of the gases was to cross the hallway and then flow down the side of the hallway opposite the compartment. This nonuniformity in gas transport within the hallway was also evident in spatial and temporal measurements of species concentrations and temperature. In the hallway, during the postflashowever period of the compartment fire, concentrations of CO greater than 2.0% were measured at locations along the wall opposite the compartment, while CO concentrations of only 0.8% were measured on the compartment side of the hallway. The data presented provides the first explanation for the tragic results of fires in health care facilities where CO inhalation was responsible for numerous deaths, and points to the necessary directions for reliable predictive tools.

Magnetic field control of burning rate and thrust in solid rocket motors

A model is developed for a flow of ionized gaseous combustion products in a channel with conducting walls. The channel is exposed to an external uniform magnetic field oriented so that the direction of the induced ponderomotive force is opposite to the flow direction. This decreases the gas flow velocity and increases the static pressure. For condensed systems, wherein the mass burning rate is proportional to external pressure and burning surface temperature, the pressure rise leads to the increased rate of combustion product generation. The determining parameters are revealed by means of numerical analysis. The influence of these parameters on the combustion process in a rectangular channel is established. It is shown that a more than tenfold increase in burning rate is possible at moderate values of the parameter of magnetogasody namic interaction. The theoretical background of the magnetic field control over the flow direction of combustion products is discussed. The essence of the method is in a certain orientation of the external magnetic field with respect to the flow of a conducting medium, which induces the ponderomotive force whose deviating component changes the direction of the flow of combustion products in channels of various configurations. The degree of deviation of a threedimensional gas flow in an axisymmetric de Laval nozzle exposed to a one-dimensional uniform magnetic field is considered.

Analysis of external burning on inclined surfaces in supersonic flow

An earlier analysis of a viscous mixing region with heat addition interacting with a supersonic external flow has been extended to include cases with a sloped wall beneath the viscous region. Also, cases with a supersonic to subsonic transition at the viscous throat have been studied for the first time. Limitations on the allowable heating value of the fuel that correspond to smooth subsonic to supersonic, or supersonic to subsonic transitions, are delineated and explained. The effects of wall slope at the throat and external Mach number on these limitations are shown. The results of calculations for representative cases show that it is possible to cancel base drag and even produce net thrust for cases with downward sloped walls if the initial Mach number in the viscous zone is supersonic prior to addition of heat. This corresponds to a supersonic to subsonic transition. For an initially subsonic flow, the results indicate pressures below the freestream static pressure throughout the flowfield. This means that only very limited drag from flameholders, such that the flow remains supersonic before heat addition, are advisable. Finally, some directions for future work are outlined.

Transport and Oxidation of Compartment Fire Exhaust Gases in an Adjacent Corridor

The oxidation of underventilated compartment fire exhaust gases during their transport down a corridor adjacent to the compartment was experimentally investigated. External burning from a compartment has been reported to decrease the toxic exhaust gas levels downstream of the compartment. The focus of the investigation was to identify the phenomena controlling the oxidation of the combustion gases external of the compartment as they traveled down a corridor during external burning. Variables in the research included the fire size, the hallway inlet and exit soffit heights, and the vent area from which the exhaust gases exit the compartment. Through gas sampling both in the hallway and in the exhaust duct downstream of the hallway, the oxidation of carbon monoxide (CO) and total unburned hydrocarbons (UHC) was studied. The concentra tions of CO and UHC were reduced from the entrance to the exit of the hallway by 65 percent and 98 percent, respectively, with no soffit at either end of the hallway. The addit...

Review : Carbon Monoxide Poisoning in Fire Victims

During fires, the effects of heat and noxious effluents are cumulative in caus ing injury to the victims. Carbon monoxide (CO), which is invariably present as a toxic component of fire emissions, often acts synergistically with cyanide released by various materials. Clinical findings are variable, depending on the extent of external burns, upper airway and lung damage, and toxic exposure. Neuropsychiatric symptoms and respiratory distress are common manifesta tions. Life-threatening complications, such as pulmonary oedema, may sud denly develop up to several days after the smoke exposure. Therapeutic mea sures include general supportive care as well as the treatment of bums and associated systemic toxicity. Arterial blood gases, carboxyhaemoglobin and cyanide levels should be monitored. Patients exposed to significant concentra tions of CO require hyperbaric oxygen therapy. Suspected cyanide poisoning must be treated without the waiting for laboratory confirmation. Untimely or incorrect intervention may c...

Carbon Monoxide Poisoning in Fire Victims

During fires, the effects of heat and noxious effluents are cumulative in causing injury to the victims. Carbon monoxide (CO), which is invariably present as a toxic component of fire emissions, often acts synergistically with cyanide released by various materials. Clinical findings are variable, depending on the extent of external burns, upper airway and lung damage, and toxic exposure. Neuropsychiatrie symptoms and respiratory distress are common manifestations. Life-threatening complications, such as pulmonary oedema, may suddenly develop up to several days after the smoke exposure. Therapeutic measures include general supportive care as well as the treatment of bums and associated systemic toxicity. Arterial blood gases, carboxyhaemoglobin and cyanide levels should be monitored. Patients exposed to significant concentrations of CO require hyperbaric oxygen therapy. Suspected cyanide poisoning must be treated without the waiting for laboratory confirmation. Untimely or incorrect intervention may compromise the chances of survival and seriously affect the future health status of fire victims.

Research on supersonic combustion

Introduction S OME qualifications to the pretentious nature of the title of this Paper are in order. Research in this context is applied, i.e., it is directed toward the design and development of devices. The devices are air breathing propulsion systems, wherein supersonic combustion is inherent or it provides an adjunct benefit. Principal applications of the former are manned hypersonic aircraft, transatmospheric accelerators, and missiles. Typical examples of the latter are external burning systems that sustain thrust or reduce drag when used in tandem with primary accelerator engines. This Paper is not at all representative of the complete body of the research on supersonic combustion. Instead, what is presented is primarily based on material with which the writer has had either direct involvement or a first-hand knowledge. It does not do justice to the exemplary works of many other investigators. Hopefully, this is somewhat rectified by the extensive list of references. The reader is encouraged to consult these manuscripts to obtain a more balanced perspective. This applied research must be viewed from the perspective of the engineer who is charged with expediting development and is in the need of design tools. Exact physics have frequently been abandoned to produce functional models. Much of the experimental verification upon which the models are based has been obtained in facilities which have known imperfections with respect to duplication of flight conditions. Moreover, compromises have been made in the analysis and interpretation of the experimental data, in part due to imperfect or incomplete diagnostic instrumentation, and in part due to a limited understanding of the underlying physics. An example that embodies all of these deficiencies would be a design model that is based on the use of integral techniques to describe combustion in supersonic flow from experiments conducted in an arc-heated tunnel.

Upper airway obstruction-an unusual complication following a minor scalding injury

A 14-month-old girl suffered a 10 per cent scalding injury from hot water of the type sometimes recognized as 'the teapot syndrome'. The hot water also reached the hypopharynx where it caused marked swelling of the mucosa and hence obstruction of the airway. Increasing respiratory distress made endotracheal intubation necessary 4.5 h after the accident. The girl was extubated 26 h later, and breathing was normal. The external burns were initially treated with baths and dressing changes. They healed mostly spontaneously, but four areas had to be grafted. This case report shows that thermal burns of the mouth and pharynx, followed by oedema and upper airway obstruction, can occur also in a minor scalding injury involving the face. Respiratory distress makes intubation necessary.

A study of carbon monoxide and smoke yields from compartment fires with external burning

Hexane fires were burned in a 2.2 m 3 compartment with a window-style exhaust vent to study the effects of external burning on carbon monoxide and smoke yields downstream of a fire compartment. External burning was observed to occur in several modes: 1) intermittent flashes, 2) bursts that lasted for only a few seconds and 3) sustained external burning. Results showed that the flammability of the compartment fire effluent was a function of the equivalence ratio and that distinguishable equivalence ratios exist that determined which mode of external burning can be obtained for a given compartment fire. Results also showed that the reduction of carbon monoxide and smoke only occurred in the presence of sustained external burning. At plume equivalence ratios above 1.7, sustained external burning always occurred and the downstream carbon monoxide yield was reduced to 10 to 25 percent of the upper layer yield and the downstream smoke yield was reduced to approximately 0 to 50 percent of the level observed prior to sustained external burning. For fires with no sustained external burning, carbon monoxide yields downstream of the compartment fire were the same as upper layer yields even when flashes or short bursts of external burning occurred. Beyler's ignition criterion for layer burning was applied to the mixing of the hot fuel-rich, upper layer gases and ambient air outside of the fire compartment. The results suggest that the ignition index predicts the potential for external burning at equivalence ratios of 1.2 and greater. However, the occurrence of external burning is dependent on the presence of an ignition source which is dictated by the vent geometry and fire size.

Pediatric laryngotracheal stenosis

Severe laryngotracheal stenosis (LTS) in children is a problem of increasing incidence in the past 15 years, following the widespread adoption of prolonged endotracheal intubation for respiratory support. Rarer cases of stenosis secondary to external trauma, high tracheotomy, thermal and chemical burns, and dystrophic cartilage are seen. In contrast to congenital subglottic stenosis, where conservative therapy is generally indicated, severe, mature LTS often requires surgical correction--either endoscopic or external reconstruction. The prevailing attitude has been to perform a tracheotomy and hope for decannulation after 1 or 2 years, due to the expected growth of the larynx. This attitude developed from experience with congenital subglottic stenosis. Unfortunately, acquired LTS tends to be a much more severe problem than congenital subglottic stenosis; the degree of obstruction is usually greater and loss of cartilaginous support of the airway commonly occurs. Some of the acquired lesions are so severe that often no lumen is demonstrable. In such cases no amount of growth will allow extubation. A variety of endoscopic methods such as dilation, with or without resection using diathermy, cryotherapy, or laser, or steroid injection are certainly helpful in the early phases of wound healing while granulation tissue is still present or while the scar tissue is still soft and pliable. To deal with the mature, hard, fibrous unresponsive scar, various authors have proposed different approaches both endoscopic and external reconstruction. The present study discusses a unique experience of external laryngotracheal reconstruction (LTR) in 100 children. In the evaluation of LTS, a thorough endoscopic evaluation is required using both flexible and rigid endoscopic techniques.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of external burning on spike-induced separated flow

W IND-tunnel measurements of the effects of burning hydrogen in a region of spike-induced separated flow are presented and analyzed. External burning is shown to eliminate the reattachment shock wave that is necessary to maintain ordinary spike-induced flow separation. This results in an additional 40-50% drag reduction beyond that achievable with the minimum drag, nonburning spike. The injectant flow rate needed to achieve a given drag reduction for a particular nose/spike geometry is shown to scale with the freestream mass flow in the enclosing streamtube.

Analysis of Base Drag Reduction by Base and/or External Burning

A simplified analysis that, however, treats all the primary physical and chemical processes of the flow has been developed. Numerical examples based on realistic values of the airstream and fuel conditions and parameters are used to illustrate the behavior of the resulting flow. It is shown that base burning at low fuel flow rates is attractive for base drag reduction. It is further shown that external burning adjacent to the base region is unattractive for base drag reduction or propulsion, either by itself or combined with base burning.

Mach 3 Hydrogen ExternaVBase Burning

Experimental studies of base pressure manipulation for an axisymmetric model at Mach 3 with cold gas injection and burning are described. Air, nitrogen, helium, and hydrogen are used for cold gas injection tests. Burning tests use hydrogen subsonically injected either radially upstream of the base plane or axially through a porous base plate. These modes of injection yielded base burning that is efficient for base drag reduction. Base burning is also combined with external compression, simulating external burning to show that the separate effects are additive.

Ignition of Liquid Fuel Jets in a Supersonic Air Stream

SEVERAL propulsion concepts, such as scramjets and external burning, involve ignition and combustion at supersonic velocities. Volume considerations have focused attention on liquid fuels; and fuel distribution, cooling, and drag studies indicate that fuel will be injected transversely from the walls. High velocities lead to low residence time and low static temperature and pressure which means long chemical times, so spontaneous ignition becomes problematical. The primary, unclassified references are presented in tabular form in the backup paper. Results with CS2 (because of low auto-ignition temperature under no-flow conditions), kerosene, JP-5, Pentaborane, TEA, HiCal and some blends are listed showing that ignition is a problem under conditions of interest. References 1 and 2 describe studies of the autoignition process for transverse liquid jets in hot, supersonic streams. The studies of no combustion cases in Refs. 3 and 4 served as motivation. It had been found that inject ant accumulated in a layer on the wall near the injector. It was postulated that residence times near this layer would be long and that ignition might initiate there. No clear evidence of ignition with CS2 or kerosene was found up to conditions where the temperature under the layer was higher than the noflow, ignition temperature for CS2 in the literature. The present study extended the work to higher temperatures, a wider range of q and other injection angles. Reference 5 showed that the layer and the separation region ahead of the jet increased for upstream angles. Contents The air temperature necessary to simulate supersonic flight was produced by a special facility consisting of two components. The first is an Inconel 601 tube heated via electric resistance. The second is an ethylene-fired preburner used to obtain temperatures higher than 1200 K. The ratio of ethylene to oxygen was determined so that the products maintained the ratio of oxygen to combustion products equal to the ratio of oxygen to nitrogen in air. The temperature profiles leaving the preburner were found to be quite uniform. It is felt that the high static temperature and pressure and the long chamber length combine to insure complete combustion in the preburner. The test nozzle was designed to produce a M = 1.65 at the injection station. At this cross section are two surface thermocouples. One is located adjacent to and slightly downstream of the injection port; the other is located circumferentially 90 deg from the injector. The liquid fuel issued into the airstream via a 0.76 mm diam port. At the same injection pressure and temperature, the ^(^pjUj/p^U^for water injection is close to that for kerosene and the q for CS2 is higher. The instrumentation included thermocouples, both wall and in-flow, pressure taps and a camera, a video camera and an infrared Thermovision thermographic camera. This camera senses the infrared radiation emitted by a heated surface, processes these images internally and produces 10color, isothermal band images on a color television screen. The exact temperature represented by each isothermal band is a function of emissivity of the object and the shape factor of the surface. These values are difficult to estimate for the liquid jet plume and surface layer here. Nonetheless, this method can be used to qualitatively observe the flow. The viewing path for the optical observations was down at an oblique angle from the rear at the emerging jet plume.