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Polymer Processing Operations
Published in Nicholas P. Cheremisinoff, An Introduction to Polymer Rheology and Processing, 1993
The purpose of the mixer ram is to keep the ingredients in the mixing area. Hence, incremented pressure would not be expected to influence mixing efficiency. In practice, however, high ram pressure has definite advantages, especially for high viscosity mixes. High ram pressures decrease voids within the mixture and increase shear stress by reducing slippage. Additionally, the effect of increasing pressure is to increase the contact force between the rubber and the rotor surface, thus increasing the critical stress so that flow begins at a lower temperature.
Module Matching
Published in Ahmed F. El-Sayed, Aircraft Propulsion and Gas Turbine Engines, 2017
There is similarity between the flow characteristics of a nozzle and a turbine [2]. The static operation of the turbojet engine is similar to the operation of a free power turbine. The equilibrium running line of the compressor (see Figure 16.12) can be obtained using the same method described in the previous section. During flight, the forward speed produces a ram pressure dependent on the flight speed (Mach number) and intake efficiency P01Pa=(1+ηdγ−12Ma2)γ/γ−1 The temperature ratio is T01Ta=(1+γ−12Ma2) The ram pressure will increase the compressor delivery pressure, which in turn increases the outlet pressure of the turbine and thus increases the pressure ratio of the nozzle. Once the nozzle is choked, the non-dimensional flow will reach its maximum value and will be independent of the nozzle pressure ratio and in turn the forward speed. This then fixes the turbine operating point due to compatibility conditions between the turbine and the nozzle. The present aeroengines operate with a choked nozzle for the whole flight except during taxiing, approaching, and landing. The nozzle map is illustrated in Figure 16.14.
A neural-network-based proportional hazard model for IoT signal fusion and failure prediction
Published in IISE Transactions, 2023
Yuxin Wen, Xinxing Guo, Junbo Son, Jianguo Wu
To investigate the performance of the proposed method through a more practical lens, in this section, we use a high-fidelity turbine engine simulation software (Mathioudakis et al.,2002). The software allows users to set different operating condition parameters to examine the influence of different operation conditions on engine performance, including flight altitude (0–15000), Mach number (0–0.90), throttle resolver angle (20–100), ambient temperature difference from ISA (-20 to 20), ram pressure recovery (0.99–1), fuel flow (0.55–1.5), low-pressure shaft speed (0–4750), high-pressure shaft speed (7300–13,280), high-pressure turbine inlet temperature (900–1400), engine pressure ratio (1.2–1.8), and thrust (15,000–230,000). Based on the operating parameters, the software simulates the working performance of the engine. In addition, the software also allows users to input indicative parameters of health conditions to control the degradation modes, including fan outer flow/efficiency drop, fan inner flow/efficiency drop, HP compressor flow/efficiency drop, HP turbine flow/efficiency drop, LP turbine flow/efficiency drop, and nozzle area change. By adjusting one or more of these parameters, the users can artificially introduce faults and simulate the working state of the engine with specific symptoms. As listed in Table 6, there are, in total, 16 variables in the outputs in response to nine operation conditions and 11 health status indicator parameters that users can manipulate. Figure 7 shows a schematic diagram of a commercial aircraft gas turbine engine for which the simulator is designed.
Eco-friendly synthesis of PET-based polymeric plasticiser and its application in nitrile-PVC rubber blends
Published in Indian Chemical Engineer, 2019
Sidhharth Sirohi, Saiyam Dobhal, Manav Doshi, Ratyakshi Nain, Krishna Dutt, Balaram Pani
The compounding was done by adding various additives such as plasticiser (DOP and PP), sulphur, filler (China clay) and activator such as zinc oxide and stearic acid. The compounding of nitrile and nitrile-PVC blend rubber was carried out on a two-roll mill. All the ingredients were mixed thoroughly at 120°C on the two-roll mill at 20 rpm for better dispersion of ingredients [20–24]. The obtained master batch was then cooled by dipping in the water tank. After cooling, the accelerator was mixed with the master batch in the two-roll mill operated at 20 rpm and 50°C. The nitrile and nitrile-PVC blend rubber sheets were prepared by compression moulding machine operated at 160°C (for both upper and lower platen). The ram pressure of compression moulding machine was kept at 160 kg/cm2 with holding time of 15 minutes and cooling time of 5 minutes [23–26].
Plasma-Jet-Driven Magneto-Inertial Fusion
Published in Fusion Science and Technology, 2019
Y. C. Francis Thio, Scott C. Hsu, F. Douglas Witherspoon, Edward Cruz, Andrew Case, Samuel Langendorf, Kevin Yates, John Dunn, Jason Cassibry, Roman Samulyak, Peter Stoltz, Samuel J. Brockington, Ajoke Williams, Marco Luna, Robert Becker, Adam Cook
It is envisaged that the target jets arrive first at the center. After stagnating to form a spherical ball of about 100 eV and relatively low density (~1024 ions per cubic meter), the target rebounds. In the meantime, the plasma guns/accelerators that launch the liner jets carry a small amount of cold, dense deuterium-tritium gas (~1 eV, ~1026 ions per cubic meter ion density) on their noses. When the afterburner and liner engage the target, the cold afterburner is sandwiched by the thermal pressure of the target and the combination of ram and thermal pressure of the liner. When the assembly is complete, the afterburner is in a pressure balance with the target and liner. This assembly is referred to as the configuration at engagement. If the afterburner is sufficiently cold, the pressure balance will cause it to be very thin by design (~1 mm thick), so that the transit time for pressure forces within the afterburner is short compared to the implosion timescale. This allows the ram pressure of the liner to be efficiently transmitted through the afterburner to implode the target. The afterburner also provides a buffer between the high-Z liner and the target to prevent mixing of the high-Z materials with the low-density target. By design, the afterburner is two orders of magnitude colder than the target; its density is about two orders of magnitude higher. By virtue of its high density, the afterburner is less vulnerable to the high-Z mixing from the liner than the target if the target is in direct contact with the high-Z liner. Also only a very thin inner layer of the afterburner needs to be ignited. The issue of the actual assembly of such a configuration and the requisite magnetization of the target and afterburner is a subject for future investigation and development. Existing plasma jet technology and magnetization techniques are not yet capable of producing these configurations. Development of new plasma gun/accelerator technologies and plasma magnetization techniques is needed.