Showing papers on "Total pressure published in 1978"
TL;DR: The augmented separation loss following coronary vasodilation probably was due to dilation of the epicardial artery adjacent to the fixed stenotic segment which caused more severe relative percent narrowing and a larger divergence angle at the distal end of the stenosis, the primary geometric determinants of separation losses.
Abstract: The pressure-flow characteristics of 100 left circumflex stenoses in 10 chronically instrumented unsedated dogs were studied under resting conditions and during pharmacological coronary vasodilation. At rest, the pressure loss (deltaP) due to a stenosis and arterial flow velocity (V) were related by the equation, deltaP = FV + SV2, where F is the coefficient of pressure loss due to viscous friction in the stenotic segment and S is the coefficient of pressure loss due to flow separation at the diverging end of the stenosis. The linear term due to viscous friction accounted for 65% and the nonlinear term due to flow separation accounted for 35% of the total pressure loss at resting coronary flow. At peak coronary flow after coronary vasodilation, the pressure loss due to viscous friction accounted for 33% and pressure loss due to flow separation accounted for 67% of the total pressure loss. The pressure gradient-velocity relationship at high flows was characterized by the same general equation but with proportionately larger values of the coefficient S and therefore greater pressure loss associated with flow separation than predicted by the resting gradient-velocity relationship. The pressure loss predicted for high coronary flow velocities on the basis of the gradient-velocity equation at rest was only 64% of the actual experimentally observed pressure gradient at peak coronary flow. The augmented separation loss following coronary vasodilation probably was due to dilation of the epicardial artery adjacent to the fixed stenotic segment which caused more severe relative percent narrowing and a larger divergence angle at the distal end of the stenosis, the primary geometric determinants of separation losses.
354 citations
Patent•
25 Jan 1978TL;DR: In this article, a partial pressure gauge utilizes an efficient electron collision excitation source yielding de-excitation radiation characteristic of residual gases, and a calibration technique based upon comparing the emitted light intensity with the ion currents associated with the excitation process yields an accurate measure of the relative partial pressure.
Abstract: A partial pressure gauge utilizes an efficient electron collision excitation source yielding de-excitation radiation characteristic of residual gases. The intensity of a given spectral line is proportional to the partial pressure of the gas having such spectral line, and the current drawn from the excitation source provides a measure of the total pressure. A calibration technique based upon comparing the emitted light intensity with the ion currents associated with the excitation process yields an accurate measure of the relative partial pressure. Use of a filter to selectively pass radiation from a known constituent in known proportion in ambient gas provides an indication of the presence of a leak without the need for probing with a test gas. Provision for passing an evaporant stream through the excitation region permits accurate monitoring of the evaporant flux from which depostion rate is determined. In combination with techniques for achieving high differential sensitivity to iluctuations in light output from a selected spectral line, a novel leak detector is achieved. In combination with an optically dispersive element a residual gas analyzer is obtained.
47 citations
TL;DR: In this article, a static apparatus for accurate measurement of total vapor pressures of solutions was constructed, which was tested by comparing obtained isothermal vapor pressures and calculated excess Gibbs free energies with literature data for the benzene - cyclohexane system at 14 and 20°C, respectively.
43 citations
TL;DR: In this article, the vapour phase kinetics of pyrolysis of cyclopropene have been studied both by product formation and reactant loss relative to an internal standard in the temperature range 466-516 K.
Abstract: The vapour phase kinetics of pyrolysis of cyclopropene have been studied both by product formation and reactant loss relative to an internal standard in the temperature range 466–516 K. The major product is methylacetylene while the minor one is allene; there is evidence for some material loss under the conditions of these experiments (partial pressures of cyclopropene, ⩽ 2 Torr ‡ highly diluted in N2 or SF6). Under conditions of minimal material loss methylacetylene is formed by a homogeneous unimolecular reaction whose rate constant is dependent on total pressure. At (70 ± 2) Torr of SF6, which is close to the high pressure limit, the following Arrhenius equation is found log k/S–1=(13.09 ± 0.04)–(156.1 ± 0.4 kJ mol–1)/RTln 10. Allene appears to be formed by two pathways, one molecular the other radical in nature. A rate constant for the former has been measured. A unimolecular “fall-off” curve for methylacetylene formation has also been obtained which spans nearly five orders of magnitude in pressure and approaches closely both high and low pressure limiting behaviour (at 495 K).The significance of these results for the direct allene to methylacetylene isomerisation is discussed; for this purpose a table of thermodynamic properties of cyclopropene is also included.
42 citations
TL;DR: In this paper, the authors used the focussed beam from a single line [P 2 (5)] of a pulsed HF laser to stimulate the decomposition of formic acid.
27 citations
TL;DR: Measurements of fluorescence quenching by oxygen under conditions of elevated pressure, a probe for studying the structure of macromolecules, show decreases in the molar volume of oxygen in solution resulted in a slight deviation from this initial trend.
26 citations
TL;DR: In this article, the A-X band of gaseous UF6 has been studied using the laser-induced fluorescence technique, and a simple kinetic model was developed to predict the dependence of the fluorescence decay lifetime on total pressure.
Abstract: The A–X band of gaseous UF6 has been studied using the laser‐induced fluorescence technique. Excitation and fluorescence spectra are presented for various pressures of UH6 at room temperature. The fluorescence spectra show little change over the pressure range 0.2–20 torr, with a peak wavelength at 421 nm. In contrast, the peak wavelength of the excitation spectra shows a noticeable shift from 391 to 385 nm when the UF6 pressure is increased from 2 to 20 torr. A Stern–Volmer plot of UF6 self‐quenching data shows a pronounced nonlinear behavior over this same pressure region. From an analysis of the laser‐induced fluorescence spectra, we develop a simple kinetic model for UF6 excited‐ state dynamics. A standard kinetic treatment of this scheme yields a prediction for the dependence of the fluorescence decay lifetime on total pressure that is in good agreement with experimental results.
24 citations
TL;DR: In this paper, a flow afterglow system and electron spin resonance detection were used to determine the diffusion coefficient of oxygen atoms in helium, which was found to be 1.08±0.12 cm2/sec.
Abstract: Chlorine atom diffusion coefficients in argon were determined using a flowing afterglow system and electron spin resonance detection. Measured values, projected to 1 atm total pressure and 295°K, were 0.26±0.05 cm2/sec. Measurements were also made of oxygen atom diffusion in helium for comparison to previously reported values for the latter system. Diffusion coefficients for oxygen atoms in helium, projected to 1 atm total pressure and 295°K, were found to be 1.08±0.12 cm2/sec in this study, compared to literature values of 1.00 and 0.72 cm2/sec.
23 citations
TL;DR: In this paper, the multiphoton dissociation of 32SF6 has been studied in the presence of several inert gases and different collisional quenching efficiencies are obtained for the various inert gases.
Abstract: The multiphoton dissociation of 32SF6 has been studied in the presence of several inert gases. The reciprocal dissociation yields increase with increasing total pressure in a nonlinear way for the conditions applied. Different collisional quenching efficiencies are obtained for the various inert gases. From the quenching efficiencies information on the optical pumping process may be obtained.
23 citations
TL;DR: Mixtures of N2O, H2, O2 and trace amounts of NO and NO2 were photolyzed at 2139 nm at 245-328 K and about 1 atm total pressure (mostly H2) HO2 radicals are produced from the photolysis, and their reactions were reported.
Abstract: Mixtures of N2O, H2, O2 and trace amounts of NO and NO2 were photolyzed at 2139 nm at 245-328 K and about 1 atm total pressure (mostly H2) HO2 radicals are produced from the photolysis, and their reactions are reported
20 citations
TL;DR: The thermal decomposition of F5SOOSF5, P, in the presence of CO has been investigated between 130.1° and 161.9°C at total pressures between 50 and 600 torr as discussed by the authors.
Abstract: The thermal decomposition of F5SOOSF5, P, in the presence of CO has been investigated between 130.1° and 161.9°C at total pressures between 50 and 600 torr. The reaction is homogeneous, and the only final products formed are CO2 and S2F10. The rate of reaction is proportional to the pressure of P. The partial pressures of CO and O2 and the total pressure have no influence on the course of reaction:
The results are explained by the following mechanism:
TL;DR: In this article, the power deposition in (U-235)F6-He fission-pumped nuclear lasers is studied. And the primary loss mechanisms are identified as the fissionfragment transport to the lasercell wall and UF6 gas excitation.
Abstract: The power deposition in (U-235)F6-He fission-pumped nuclear lasers is studied. Specifically, means to maximize the energy density in the He gas are assessed. Primary loss mechanisms are identified as the fission-fragment transport to the laser-cell wall and UF6 gas excitation. The losses are thus strongly dependent on UF6 concentration. It is found that maximum power will be deposited in a laser tube when the tube radius is as large as the range of fission fragments. Experimental results indicate that when the tube radius equals the fission-fragment range, the ratio of a UF6 partial pressure to total pressure is 0.15, and the UF6-He mixing ratio is 1:6, maximum power will be deposited.
Abstract: Resolved rotational levels in the vibrational states 7 v′ 3 of electronically-excited B3Π(0+) BrCl molecules have been excited, using pulses from a narrow-band tunable dye laser. Fluorescence lifetimes((τ= 1/Γ) have been measured as a function of J′, v′ and pressure.All rotational levels of the v′= 7 state of 79Br35Cl(B) were predissociated. Their lifetimes were found to shorten systematically with increase in rotational energy, from 0.91 µs for J′= 7 down to 0.24 µs for J′= 16.In order to suppress disproportionation of BrCl, all studies were carried out using BrCl mixed with typically a seven-fold excess of Cl2. Both upward and downward vibrational energy (V ↔ V) transfer was found to be significant above 30 mTorr total pressure, within the relatively long lifetimes (⩽25 µs) of the lower vibrational states (v′⩽ 6) of BrCl(B). Lifetime measurements were made in two separate total pressure ranges: at low pressure, from 30 to 200 mTorr; and at high pressures, from 3 to 11 Torr.At low pressures, a strong pressure-dependence of the fluorescence decay rate constant Γ was found. This pressure-dependent rate is attributed almost entirely to rapid vibrational transfer, which depletes the population of emitters by upward V ↔ V transfer into the unstable part of the energy level manifold above v′= 6. Values for the lifetime, extrapolated to zero pressure, for v′= 4, 3, were determined to be (τ0= 35+11–9)µs.After the first few µs, fluorescence decay at high pressures was exponential; Γ for this regime showed a much less marked dependence on total pressure than at low pressures. Vibrational relaxation is essentially complete under these conditions, and the pressure-dependence of Γ is attributed to quenching of a Boltzmann distribution of BrCl(B) molecules consisting of ∼75 % in v′= 0 and ∼25 % in v′= 1. However, electronic quenching is relatively slow, and for BrCl + Cl2(90 %) mixtures, has collision efficiency around 2 × 10–3.
Patent•
01 May 1978
TL;DR: In this paper, the ratio of burner pressure to engine inlet total pressure generated as a function of corrected rotor speed multiplied by a calculated engine total pressure from aircraft altitude and Mach No. simulates burner pressure utilized in the main fuel control for continuing automatic engine operation.
Abstract: For a failure of a sensor utilized in the controls for a gas turbine engine, calculations from other parameters based on the thermodynamics of the cycle serve to simulate the value otherwise manifested by the failed sensor. In this instance, the ratio of burner pressure to engine inlet total pressure generated as a function of corrected rotor speed multiplied by a calculated engine total pressure from aircraft altitude and Mach No. simulates burner pressure utilized in the main fuel control for continuing automatic engine operation.
TL;DR: In this article, a method for computing the discharge threshold voltages in SF6, N2 as well as their mixtures above atmopheric pressure was developed for both uniform and nonuniform field gaps of positive polarity.
Abstract: A method is developed for computing the discharge threshold voltages in SF6, N2 as well as their mixtures above atmopheric pressure. In electronegative gases, and for both uniform and nonuniform field gaps of positive polarity, there is a critical pressure above which field emission from the cathode surface has a significant effect. The method of calculation is based on the condition necessary for the onset streamer to propagate. The effect of increased pressure over the critical value is that spark breakdown takes place within the discharge gap unpreceded by any corona. The computed values are in good agreement with those measured experimentally at pressures below and above the critical value for both uniform and nonuniform field gaps. The present calculations confirm those predicted experimentally, namely, there is no significant difference in the behavior of pure SF6 and mixtures up to 50 percent of N2. The fact that mixtures can show a higher breakdown voltage at the same total pressure than pure SF6 is also confirmed.
Patent•
06 Jul 1978
TL;DR: In this article, the authors proposed a method for reducing the temperature of bakery products by means of vacuum by subjecting the bakery products to a substantially linear pressure reduction as a function of time at a rate of not more than 60 mm Hg per second through at least half of the total pressure drop to be achieved.
Abstract: The temperature of bakery products is reduced immediately after the discharge thereof from the oven, by means of vacuum, by first subjecting the bakery products to a substantially linear pressure reduction as a function of time at a rate of not more than 60 mm Hg per second through at least half of the total pressure drop to be achieved. The pressure reduction rate is then allowed to increase substantially for a terminating vacuum treatment. At least one vacuum chamber is provided and is adapted to be connected to a source of vacuum though a vacuum conduit and a valve, and has a closeable opening for bringing bakery products into and out of the chamber. In the vacuum conduit, in parallel to a servo-valve serving to apply a full vacuum effect from the source of vacuum during the remaining portion of the total pressure drop, there is inserted a by-pass conduit having a permanently open cross-section which can be adjusted to provide the substantially linear pressure reduction.
TL;DR: In this article, a part of the mass-spectrometer shock-tube apparatus was improved and its working characteristics were examined, and the oxidation of methane was studied with this apparatus over the temperature range of 1800-2500 K and the total pressure range of 360-560 Torr at O2/CH4 ratios of 1-3.54×10−10[CH4]0.37[O2]−0.64exp(35600⁄RT) s in which the concentrations were expressed in mol per cubic centimeter.
Abstract: A part of the mass-spectrometer shock-tube apparatus was improved, and its working characteristics were examined. The oxidation of methane was studied with this apparatus over the temperature range of 1800–2500 K and the total pressure range of 360–560 Torr at O2/CH4 ratios of 1–3. The induction period was measured by monitoring the oxygen concentration, and the following equation was found to hold: τ=4.54×10−10[CH4]0.37[O2]−0.64exp(35600⁄RT) s in which the concentrations were expressed in mol per cubic centimeter.
TL;DR: In this article, it was shown that the effectiveness of an isothermal, first order, gas-phase catalytic reaction may be increased by operation under conditions of oscillating total pressure.
25 Jul 1978
TL;DR: In this article, an experimental investigation was conducted involving coaxial dump combustors with two different types of flameholders (annular and Y) installed at the dump station in an attempt to correlate combustor performance with previous non-reacting flowfield results.
Abstract: : An experimental investigation was conducted involving coaxial dump combustors with two different types of flameholders (annular and Y) installed at the dump station in an attempt to correlate combustor performance with previous non-reacting flowfield results. Flameholder blockage, combustor length, exit area ratio, inlet temperature, and chamber pressure were varied for both all injection and premixed fuel conditions. Lean blowout limits, combustion efficiency, combustor total pressure drop, and wall static pressure distributions were obtained from these runs using JP-4 fuel. In addition, a limited amount of surface heating patterns and combustion oscillation data were obtained.
TL;DR: In this article, an analytical model was constructed which relates the emitted spectral intensity to the local temperature and radiating species concentration within the gas, and the profiles within a gas were determined by inverting these integral equations through the use of a parameter estimation inversion technique.
01 Jun 1978
TL;DR: In this paper, an electronically stabilized, grating tunable cw CO2 laser with a nominal output power of 2 watts was used in performing measurements of water vapor absorption as a function of both pressure and temperature.
Abstract: : Water vapor absorption at CO2 laser frequencies has been studied using a differential spectrophone and a long path multiple traversal cell. The results of these measurements have been analyzed in terms of the Lorentz line shape and the far wing model for continuum absorption in the 9-10 micrometers wavelength region. An electronically stabilized, grating tunable cw CO2 laser with a nominal output power of 2 watts was used in performing measurements of water vapor absorption as a function of both pressure and temperature. Pressure broadened studies of H2O in N2 at a total pressure of 1 atm. were performed at 27 CO2 laser lines in the 9.4 and 10.4 micrometers bands. A technique for pure (low pressure) H2O measurements using the spectrophone is presented together with some preliminary results at the 10.6 micrometers P(20) laser line. White cell measurements of pure water vapor were performed at seven laser lines in the 9.4 and 10.4 micrometers bands; these data also indicate a significant negative temperature dependence for continuum absorption.
01 Mar 1978
TL;DR: In this paper, a 1.37m airfoil was tested in a 03m transonic cryogenic tunnel at free stream Mach numbers of 075, 085, and 095 over a total pressure range from 12 to 50 atmospheres.
Abstract: A 0137m airfoil was tested in a 03m transonic cryogenic tunnel at free stream Mach numbers of 075, 085, and 095 over a total pressure range from 12 to 50 atmospheres The onset of condensation effects were found to correlate more with the amount of supercooling in the free stream than it did with the supercooling in the region of maximum local Mach number over the airfoil Effects in the pressure distribution over the airfoil were generally seen to appear over its entire length at nearly the same total temperature Both observations suggest the possibility of heterogeneous nucleation occurring in the free stream The potential operational benefits of the supercooling realized are presented in terms of increased Reynolds number capability at a given tunnel total pressure, reduced drive fan power if Reynolds number is held constant, and reduced liquid nitrogen consumption if Reynolds number is again constant Depending on total pressure and free stream Mach number, these three benefits are found to respectively vary from 7 to 19%, 11 to 25%, and 9 to 20%
01 Jul 1978
TL;DR: In this paper, an inexpensive method is developed to determine the extreme values of instantaneous inlet distortion, which is based on fundamental fluid dynamics and statistical methods to provide an understanding of the turbulent inlet flow and quantitatively relate the rms level and power spectral density (PSD) function of the measured time variant total pressure fluctuations to the strength and size of the low pressure regions.
Abstract: An inexpensive method is developed to determine the extreme values of instantaneous inlet distortion. This method also provides insight into the basic mechanics of unsteady inlet flow and the associated engine reaction. The analysis is based on fundamental fluid dynamics and statistical methods to provide an understanding of the turbulent inlet flow and quantitatively relate the rms level and power spectral density (PSD) function of the measured time variant total pressure fluctuations to the strength and size of the low pressure regions. The most probable extreme value of the instantaneous distortion is then synthesized from this information in conjunction with the steady state distortion. Results of the analysis show the extreme values to be dependent upon the steady state distortion, the measured turbulence rms level and PSD function, the time on point, and the engine response characteristics. Analytical projections of instantaneous distortion are presented and compared with data obtained by a conventional, highly time correlated, 40 probe instantaneous pressure measurement system.
09 Apr 1978
TL;DR: In this paper, the authors measured static and total pressure, total temperature, and flow angle profiles along the whole diffuser length in a high specific speed compressor and showed that the flow has a completely distorted inlet profile from the front to the back wall of the diffuser.
Abstract: The exit flow distribution of 90-deg centrifugal compressor impellers is distorted in peripheral direction as well as over the diffuser depth. First, there are the rotating jet-and-wake regions behind each impeller channel. Second, the flow has a completely distorted inlet profile from the front to the back wall of the diffuser. Measurements of static and total pressure, total temperature, and flow angle profiles along the whole diffuser length have been carried out in a high specific speed compressor. The results show great angle and total pressure differences in the first part of the diffuser and a backflow zone near the front wall. At the end of the diffuser, a separation zone was located. It is shown that by means of a one-dimensional calculation method, using a dissipation factor, the measured representative mean values of the diffuser flow can be determined very well in the regions where no separation occurs.Copyright © 1978 by ASME
14 Jun 1978
TL;DR: The results of a study of total pressure and velocity circumferential distortions in an axial-flow fan are presented in this paper, where the flow through an isolated rotor was examined at various operating conditions with six different distortions and three different blade stagger angles.
Abstract: The results of a study of total pressure and velocity circumferential distortions in an axial-flow fan are presented. Some of the fundamental experimental data needed to understand distorted flow phenomena as affected by design and operating variables are provided. The flow through an isolated rotor was examined at various operating conditions with six different distortions and three different blade stagger angles. Circumferential surveys were conducted upstream and downstream of the rotor using five-hole probes in the nonnulling mode. The total pressure and axial velocity distortion data were analyzed to determine the degree of distortion attenuation as a function of blade stagger angle, mean incidence angle, and reduced frequency. The results indicate that, for the rotors tested, the mean incidence or loading has very little effect on the distortion attenuation.
TL;DR: In this article, the authors investigated the resonance tubes for M = 3.2-4.0 and showed that pressure oscillations can occur at these Mach numbers with the peak-topeak amplitude of ΔP ≈ 0.4·Po, where Po is the total pressure in the inflowing jet.
Abstract: The formation of pressure fluctuations at the inflow of a jet into a cavity (or the so-called resonance tube) was first observed by Hartmann. Further investigations showed that at the same time there is a heating of the gas in the cavity [1, 2]. It was established in [1, 2] that at subsonic and slightly supersonic velocities (M < 2.0) the cavity air can be heated up to 500–700 °K. Further investigations [4, 6] showed that by using monatomic gases inside the cavity one can reach even higher temperatures (T ≈ 800–900 °K). The resonance tubes find an application as powerful sound sources. There is also a possibility of their use in thermochemistry, and for the plasma production [6], In the literature, there is an absence of data on the resonance tube characteristics for large Mach numbers. In the present work we investigate the resonance tubes for M = 3.2–4.0. These investigations have shown that pressure oscillations can occur at these Mach numbers with the peak-to-peak amplitude of ΔP ≈ 0.4·Po, where Po is the total pressure in the inflowing jet. Depending on the clearance between the nozzle and the cavity, both low- and high-frequency oscillations can be set up. It is established that the most intense shock-wave heating of the gas takes place at high-frequency fluctuations, although their amplitude is smaller in comparison with the low-frequency ones. It is shown that the cold air inside the cavity can be heated by means of the fluctuations up to T ≈ 1600 °K or more.
01 Jan 1978
TL;DR: In this article, an inlet and duct were successfully developed which removed airflow from the engine fan duct for the boundary layer control (BLC) system at or above the required total pressure of 99% of the average fan duct total pressure.
Abstract: The boundary layer control (BLC) system of the quiet short-haul research airplane (QSRA) requires significant amounts of pressurized airflow for successful operation. An inlet and duct were successfully developed which removed airflow from the engine fan duct for the BLC system at or above the required total pressure of 99% of the average fan duct total pressure. The design was constrained by the tight space limitations of the QSRA nacelle. Potential flow with boundary layer analysis techniques were used as an aid to select the inlet and duct geometries. Airflow and total pressure profile data were obtained during development tests.
TL;DR: In this paper, the preparation of pseudobrookite (Fe 2 TiO 5 ) single crystals by chemical transport in a closed system with TeCl 4 as a carrier was studied.
01 Apr 1978
TL;DR: Even though these results are derived from a simple model far from the complexity of the actual vasculature, the basic concepts would remain valid even if more complex mathematical treatments would have been used.
Abstract: An inhomogeneous linear one-dimensional mathematical model is constructed as a conceptual approach to the study of the effects of External Counterpulsation (ECP) on the pressure and flow at the root of the aorta. The optimal operation of ECP is defined by two conditions: (1) minimization of the mean systolic pressure; and (b) maximization of the ratio of diastolic area over systolic area under the total pressure curve. The phase shift of the external pressure is determined so as to satisfy these two requirements. It is demonstrated within our approximation that with a given magnitude of external pressure, the phase shifts that satisfy these two requirements are the same. These phase shifts are linear functions of the systolic fraction of the total cardiac period, and depend on the time for the external wave to travel from the site of application up the vascular bed to the root of the aorta, plus the reflection contributions. Even though these results are derived from a simple model far from the complexity of the actual vasculature, the basic concepts would remain valid even if more complex mathematical treatments would have been used.
01 Jun 1978
TL;DR: In this paper, peak distortion data taken from a subscale inlet model were studied to determine if the data can be used to predict peak distortion levels for a full scale flight test vehicle, and to provide a better understanding of the time variant total pressure distortion and the attendant effects of Reynolds number/scale and frequency content.
Abstract: Peak distortion data taken from a subscale inlet model were studied to determine if the data can be used to predict peak distortion levels for a full scale flight test vehicle, and to provide a better understanding of the time variant total pressure distortion and the attendant effects of Reynolds number/scale and frequency content. The data base used to accomplish this goal covered a range from Mach 0.4 to 2.5 and an angle of attack range from -10 degrees to +12 degrees. Data are presented which show that: (1) increasing the Reynolds number increases total pressure recovery, decreases peak distortion, and decreases turbulence, (2) increasing the filter cutoff frequency increases both peak distortion and turbulence, and (3) the effect of engine presence on total pressure recovery, peak distortion, and turbulence is small but favorable.