Compressor design is always a prevalent research issue as nowadays the compressor demands higher performance. Designing afresh a new compressor of higher aerodynamic performance will cost a tremendous amount of time and expense. Consequently, the wiser method of acquiring a higher performance compressor is to optimize a current compressor, discussed in this paper. First, a detailed numerical simulation of al compressor is done. A parametric rotor model is created and the variations of lean and swept parameters are limited. Then, an optimization calculation is carried out based on the combination of an artificial neural network and a genetic algorithm. The optimization iteration is started at three specified working points – a choke point, a design point and a near stall point – to acquire a comprehensive improved solution. A novel penalty function considering both pressure ratio and efficiency is constructed to find the optimal model. Finally, a detailed review is made of the original and the optimized compressor. The computational results show that the isentropic efficiency is successfully increased and the stall margin is remarkably improved. Ultimately, a detailed vortex structure analysis with increasing outlet pressure is discussed. This helps the performance increment mechanism to be understood further.

Micro-cooling is a growing trend in the field of turbine blade cooling. Technical difficulties in the experiments of large-aspect-ratio rectangular microchannels that are commonly used in the turbine blades cause the rareness of related literature. In this study, the flow characteristics and heat transfer performance of the microchannels with and without semi-ellipsoidal protrusions, whose height is 0.6 mm and width is 9 mm, are numerically investigated. In the microchannel without protrusions, when 2214 < Re < 3589, the velocity has a Λ-shaped distribution, resulting in a Λ-shaped Nu distribution on the wall. When Re > 3760, it is worth noting that from the sidewall to the middle of the channel, Nu first decreases and then increases. In the microchannel with protrusions, when Re < 1214, the turbulence formed by the protrusion is almost all behind it and does not spread to both sides. When 1214 < Re < 2374, the turbulence caused by the protrusions gradually spreads to the middle and both sides of the channel with the increase in Re. When 2374 < Re < 3815, the turbulence caused by two columns of protrusions meet in the middle of the channel and forms stronger turbulence downstream. When Re > 3815, the flow is all turbulent. The protrusions enhance the irreversibility of heat transfer and friction. The performance evaluation criteria (PEC) increases first and then decreases with Re and the maximum value is 1.80 at Re = 2004. In this work, the details that are difficult to obtain in experiments are fully analyzed to provide suggestions for the design of micro-cooling structures in gas turbine blades.

To enhance the impingement cooling performance of turbine blades, this study investigates the heat transfer mechanisms of triangular-wing longitudinal vortex generators (TLVGs) arranged on the target surface. TLVGs are evaluated under different heights (H), widths (W), and angles (α) within a Reynolds number range of 4000 to 10 000. The main conclusions are as follows: Increasing H leads to an increase in heat transfer on the target surface and flow resistance, with the optimal overall heat transfer performance observed at H = 0.5D, improving thermal performance factor (TPF) by 7.5%–9.0% compared to a smooth target surface. The effect of W on the heat transfer performance of the target surface is relatively small, and its increase slightly reduces flow resistance. For Reynolds numbers below 6000, the TLVG with W = 0.1D shows the best overall heat transfer performance; however, for Reynolds numbers above 6000, the TLVG with W = 0.4D exhibits the optimal performance. The TLVG at α = 60° significantly reduces flow losses in the impingement chamber, improving TPF by 6.8%–8.2% compared to a smooth target surface. The TLVG at α = 150° has the next highest TPF, improving by 5.3%–6.0%, but it enhances heat transfer capability more effectively than at α = 60°.

The performance of turbomachinery blade profiles, at low Reynolds numbers, is influenced by laminar separation bubbles (LSBs). Such a bubble is caused by a strong adverse pressure gradient (APG), and it makes the laminar boundary layer to separate from the curved profile surface, before it becomes turbulent. The paper consists on a joint experimental and numerical investigation on a flat plate with adverse pressure gradient. The experiment provides detailed results including distribution of wall pressure coefficient and boundary layer velocity and turbulence profiles for several values of typical influencing parameters on the behavior of the flow phenomena: Reynolds number, free stream turbulence intensity, and end-wall opening angle, which determines the adverse pressure gradient intensity. The numerical work consists on carrying out a systematic analysis, with Reynolds Average Navier-Stokes (RANS) simulations. The results of the numerical simulations are critically investigated and compared with the experimental ones in order to understand the effect of the main physical parameters on the LSB behavior. For RANS simulations, different turbulence and transition models are compared at first to identify the adaptability to the flow phenomena; then, the influence of the three aforementioned parameters on the LSB behavior is investigated under a typical aggressive adverse pressure gradient. Boundary layer integral parameters are discussed for the different cases in order to understand the flow phenomena in terms of flow time-mean properties.

The design of marine gas turbine exhaust system is related to the normal operation of gas turbine and even the overall performance indexes of the ship. In this paper, the influence of exhaust system on the gas turbine, the infrared stealth performance of the whole ship and ship surface equipment is specifically analyzed. In view of these influences, the main points of design of marine gas turbine exhaust system are presented in this paper, which can provide reference for the design of gas turbine exhaust system. The Design points includes: (1) the exhaust system resistance, (2) the cooling air injection effect of the exhaust system case body, (3) improving the infrared stealth performance of the exhaust system, (4) smoke outlet position of exhaust system.