Supersonic Magnetohydrodynamic (MHD) Power Generation System and Its Preliminary Experiment
Magneto hydrodynamic (MHD) power generation system has an important potential application in high-speed aero craft. According to the principles of MHD power generation, shock tunnel and ionization, a supersonic MHD power generation system is developed and introduced in this paper. Helium is used for driver gas and argon for driven gas. Equilibrium contact surface operating mode is selected to obtain high temperature, and the K2CO3 powder seed is added into the driven section so that the supersonic flow is electric. When M=2.0 and B=0.5 T, the power generation system is set up to know the experimental conditions. The nozzle entry total pressure is about 0.35 MPa while total temperature about 3965.1 K, and the nozzle exit velocity is calculated 1530.8 m/s. A preliminary experimental investigation is at length carried out by measuring the voltage and current of the segmented MHD power generation channel. Average electrical conductivity is estimated to be 15 S/m approximately. When load factor is 0.5, the maximum power density of this MHD power generation channel is about 2.195 MW/m3, while the maximum value of enthalpy extraction rate tends to be about 0.255%.
Helmholtz Resonance of Pitot Pressure Measurements in Impulsive Hypersonic Test Facilities
Experimental pitot pressure measurements in impulse facilities have typically had large scale harmonic fluctuations associated with them. A combined experimental and numerical approach is used to investigate if a Helmholtz resonance is created from the shrouding that protects the pressure sensor from particle impact, rather than disturbances being present in the free stream. To verify this experimentally, hydraulic oil was used to change the sound speed in the cavity. Numerical calculations of the pitot probe were used to show that both the steady and the expected transient inflow cause a Helmholtz resonance of similar period. However, a 5% isothermal level of free stream noise was required to match the experimental fluctuation levels. Also, viscous eects were shown to be significant during the initial transient response of the pressure measurement. A new pitot probe design was successfully tested and shown to be able to reduce the magnitude and period of the fluctuations.
Evaluation of Analgesic Effect of Caudal Epidural Tramadol, Tramadol-Lidocaine, and Lidocaine in Water Buffalo Calves (Bubalus bubalis)
Aim of this study was to compare the analgesic effect of tramadol and a combination of tramadol-lidocaine with that produced by lidocaine administration in the epidural space in buffalo calves. In a prospective randomized crossover study, ten male buffalo calves were used to compare the epidural analgesic effect of tramadol (1 mg/kg) and tramadol-lidocaine combination (0.5 mg/kg and 0.11 mg/kg, resp.) with that produced by 2% lidocaine (0.22 mg/kg). Loss of sensation was examined by pin-prick test. Onset time, duration, and degree of analgesia and ataxia were recorded after each treatment. Heart rate (HR), respiratory rate (RR), rectal temperature, and haematobiochemical parameters were recorded after all treatments. Time to onset and duration of analgesia, respectively, were as follows: tramadol 11 ± 2 min and 208 ± 15 min; tramadol-lidocaine 6 ± 2 min and 168 ± 9 min; lidocaine 4 ± 1 min and 67 ± 13 min. Onset time and duration were significantly longer with tramadol than the other treatments. Duration was significantly longer with tramadol-lidocaine than lidocaine. Ataxia was mildly observed in tramadol-lidocaine and was moderate in lidocaine. HR, RR, and rectal temperature did not differ significantly from baseline after any treatment. Haematobiochemical parameters returned to basal levels by 24 h after all treatments. This combination might be clinically useful to provide analgesia in buffalo for long-duration surgical procedures.