This paper describes the development of a high performance low pressure turbine (LPT) for turbocompounding applications to be used in a 1.0 litre ”cost-effective, ultra-efficient gasoline engine for a small and large segment passenger car”. Under this assumption, a mixed-flow turbine was designed to recover latent energy of discharged exhaust gases at low pressure ratios (1.05 - 1.3) and to drive a small electric generator with a maximum power output of 1.0 kW. The design operating conditions were fixed at 50,000 rpm with a pressure ratio of 1.1. Commercially available turbines are not suitable for this purpose due to the very low efficiencies experienced when operating in these pressure ratio ranges. The low pressure turbine performance was simulated using a commercial CFD software. Then, turbine performance was validated with a comprehensive turbine testing that was accomplished by using the Imperial College turbine test rig. The testing and the simulation conditions were conducted for a range of design equivalent speeds spanning between 80% and 120% at steps of 10% increase. In addition, the impact of the turbocompounding on Brake Specific Fuel Consumption (BSFC) and Brake Mean Effective Pressure (BMEP) was also assessed by using a 1-D validated engine model of the engine under study. Three different arrangements for the turbocompounding were assessed: (1) precatalyst, (2) post-catalyst and (3) in the wastegate of the main turbocharger. The outcomes of the simulation were compared to those obtained for the baseline engine and are discussed in the the paper. The 1-D engine simulation had shown that the maximum benefit of the turbocompounding can be achieved when it was located at the post catalyst with maximum BSFC reduction of 2.4% at 1500 rpm and 3.0% of BMEP increase at 1000rpm.

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This paper presents the development of numerical methods for modeling non-equilibrium condensing flows in steam turbines. The method is within Eulerian-Eulerian Framework. A Roe convective flux is derived, which is featured on using real steam property and fully coupling wetness fraction with other conservative variables in the Jacobian matrix. The analytical expressions of eigenvalue, right and left side eigenvectors are derived. The real steam property treatment is enlightened by the two-dimensional TTSE method, and the current paper extended it to three dimensions which exhibits great convenience for Eulerian-Eulerian Framework. Quadrature Method of Moments (QMOM) is implemented to model polydisperse droplet spectrum. To overcome instable issues caused by moment corruption, which is inevitable during steady state time marching, a correction scheme for moments is applied. Example calculations on nozzles and a turbine cascade are provided. Results show that the current model is robust and correct. QMOM is capable of representing the polydisperse droplet spectrum. Correction schemes play a crucial role for the stability and accuracy of QMOM.

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This paper presents an original control system design that enables electrical load-following with GTHTR300C, a nuclear gas turbine cogeneration plant under development by JAEA for potential deployment in developing countries. The plant operates on a closed Brayton cycle directly heated by the helium gas coolant of a small-sized Generation IV High Temperature Gas-cooled Reactor (HTGR), also known as Very High Temperature Reactor (VHTR). The control system is designed to follow daily electric load by taking advantage of the unique operation characteristics of the nuclear reactor and closed cycle gas turbine and the direct interface of the nuclear heat source and gas turbine engine. The control system integrates several fundamental control methods and permits wide-ranging load follow at constant reactor power and high thermal efficiency, which maximizes plant economics. Control simulation of the overall plant system to follow daily load changes representative of developing countries are performed using a system analysis code in order to demonstrate a technical feasibility of the system. The observable operation parameters essential to the system control are identified that include reactor outlet temperature, turbine inlet temperature, gas turbine rotational speed, and so on. The simulations results show that the load-follow can be effectively carried out by monitoring these parameters and controlling them with suitable control apparatus.

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