Stagnation pressure/temperature

From (a) and (b), the stagnation pressure and temperature can thus be calculated at exit from the cooled row they can then be used to study the flow through the next (rotor) row. From there on a similar procedure may be followed (for a rotating row the relative (7 o)r, i and (po)k replace the absolute stagnation properties). In this way, the work output from the complete cooled turbine can be obtained for use within the cycle calculation, given the cooling quantities ip. 

Two-dimensional compressible momentum and energy equations were solved by Asako and Toriyama (2005) to obtain the heat transfer characteristics of gaseous flows in parallel-plate micro-channels. The problem is modeled as a parallel-plate channel, as shown in Fig. 4.19, with a chamber at the stagnation temperature Tstg and the stagnation pressure T stg attached to its upstream section. The flow is assumed to be steady, two-dimensional, and laminar. The fluid is assumed to be an ideal gas. The computations were performed to obtain the adiabatic wall temperature and also to obtain the total temperature of channels with the isothermal walls. The governing equations can be expressed as... 

Equation (4.4), which connects the known variables, unbumed gas pressure, temperature, and density, is not an independent equation. In the coordinate system chosen, //, is (lie velocity fed into the wave and u2 is the velocity coming out of the wave. In the laboratory coordinate system, the velocity ahead of the wave is zero, the wave velocity is uh and (u — u2) is the velocity of the burned gases with respect to the tube. The unknowns in the system are U, u2, P2, T2, and p2. The chemical energy release is q, and the stagnation adiabatic combustion temperature is T, for n-> = 0. The symbols follow the normal convention. 

It is obvious that the entropy change will be positive in the region Mi > 1 and negative in the region Mi < 1 for gases with 1 < y < 1-67. Thus, Eq. (1.46) is valid only when Ml is greater than unity. In other words, a discontinuous flow is formed only when Ml > 1. This discontinuous surface perpendicular to the flow direction is the normal shock wave. The downstream Mach number, Mj, is always < 1, i. e. subsonic flow, and the stagnation pressure ratio is obtained as a function of Mi by Eqs. (1.37) and (1.41). The ratios of temperature, pressure, and density across the shock wave are obtained as a function of Mi by the use of Eqs. (1.38)-(1.40) and Eqs. (1.25)-(1.27). The characteristics of a normal shock wave are summarized as follows ... 

Dunkle (Ref 40) points out that total pressure is also known as stagnation pressure and is equal to the sum of static pressure and dynamic pressure. Both of these are exerted by gases. More detailed explanation is given in Ref 40, p 32. He also states that in the reaction between A1 K chlorate, mentioned above, the products formed at the temperature of explosion are gaseous KC1, AlO, A O and oxygen. The A Oj does not form until the products cool... 

The femtosecond laser pulses shaped by the AOPDF are amplified by the CPA up to 0.5mJ/pulse. Ethanol vapor is continuously flow into the vacuum chamber through a micro-syringe (70 pm) with stagnation pressure of 7 Torr at room temperature. The laser pulses are focused on a skimmed molecular beam of the ethanol vapor with an achromatic lens (/ = 145 mm). The focal spot size of the laser beam is 20 pm(j>. The peak intensity of the transform-limited laser pulse is calculated to 4 x 1015 W/cm2. The fragment ions are mass-separated with Wiley-McLaren type time-of-flight (TOF) mass spectrometer, and are detected with a microchannel plate (MCP) detector. 

Figure 15-16. (a) Vapor absorption spectrum of tolane at room temperature, (b) Fluorescence excitation spectrum of tolane in a supersonic free jet. The stagnation pressure of He is four atm. (c) Two-photon absorption spectrum of tolane in a supersonic free jet obtained by two-photon resonant four-photon ionization. The stagnation pressure of He is four atm. (Reprinted with permission from Ref. [35].)... 

The beam intensities of oriented molecules using hexapole eleetrie field, however, turn out to be poor because the state selection requires a veiy large flight-length as compared with eonventional molecular beam set-ups. In order to increase the beam intensity, one may propose a way to increase the stagnation pressure of the nozzle. However, the eharaeteristies of the molecular beam such as stream veloeity, rotational temperature and the size distribution of clusters are generally changed [41]. Motivation of the study of Ref.[2] has been to develop a new type of electrostatic state-selector in order to produee an intense oriented molecular beam. Basic idea of this experiment has been that the beam intensity should be simply proportional to the number of beam lines if the moleeular beams can be focused on a point in space. 

Experiments were conducted in the newly built High Temperature Supersonic Jet Facility at the Fluid Mechanics Research Laboratory of the Florida State University in Tallahassee. A schematic of the facility can be seen in Fig. 3.2. In the present experiments, a converging axisymmetric nozzle having an exit diameter of 50.8 mm Wcis used. The nozzle profile was designed using a fifth-order polynomial with a contraction ratio of approximately 2.25. The stagnation pressure and temperature were held constant to within 0.5% of its nominal value during the experiment. 

Fig. 42. Dispersed Huorescence spectra from the level of aniline, taken in a pulsed supersonic jet at x=3, where the temperature is 25 °K. Note the bands that grow in when the stagnation pressure is increased, indicating that very low energy collisions with the He atoms of the carrier gas are efficient at redistributing the vibrational energy of the aniline molecule.

I- 1 REMPI of S( P2,i,o> D2)IC H S. The experimental setup and procedures used to measure the electronic S( P2.i,o, 2) state distribution formed in the 193-nm photodissociation of organosulfur species have been described in Section II.A [58-60]. In this experiment, a pulsed molecular beam of neat thiophene is produced by supersonic expansion through a pulsed valve (nozzle diameter = 0.5 mm, temperature 298 K, stagnation pressure = 90 Torr). 

Figure 5.3 Free jet center line beam velocity (u/uj, temperature T/TJ, gas density (n/nj, and hard sphere collision frequency (v/vj as a function of the distance from the nozzle, in units of nozzle diameters for the case of 7 = 5/3. Note that none of these parameters depends upon the stagnation pressure. Taken with permission from D.R. Miller (1988).

The terminal Mach number can be inserted into Equation (5.8) to determine the final translational temperature. For the case of the experiment shown in Figure 5.2, in which the stagnation pressure is 6.5 atm and the nozzle diameter is 50 p.m, the final parallel translational temperature is calculated to be 2.4 K (compared to the experimentally determined value of 1 K). 

Figure 5-40. Typical parameters of a nozzle system in supersonic plasma-chemical experiments. Subscripts 1 and 2 are related to inlet and exit of a discharge zone subscript 3 is related to exit from the nozzle system subscript 0 is related to stagnation pressure and temperature.

Figure 11-2. General schematic of the experimental setup for (a) the hypersonic microwave ignition and (b) the time evolution of stagnation pressure and temperature in the system.

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