The article substantiates application of exhaust and transition diffusors to increase the effectiveness and decrease the noise of gas turbine units. It presents assessment of methods of increasing the effectiveness of exhaust and transition diffusors of industrial gas turbine units, and formulates the task for mathematical modeling of flow in conic diffusor with high flare and over-critical angle of expansion with flow stabilization by tangent twisted blow.
gas turbine unit, aerodynamic noise, diffusor, flow vortex, pressure increase ratio, slowing rate, tangent blow, expansion angle of diffusor.
1. Введение
В настоящее время все более широкое распространение получают газотурбинные энергетические установки (ГТУ) малой и средней мощности блочномодульного исполнения. Основой для их создания чаще всего служат конвертированные авиационные и транспортные газотурбинные двигатели, особенностью которых является значительная расходная скорость при выходе из турбины (CT = 180–250 м/с) [1–3], а для двухконтурных тригенерационных установок, созданных на базе авиационных двигателей с малой степенью двухконтурности m = 0,3–1,0 (отношением расхода воздуха во втором контуре к расходу через газогенератор), еще и за компрессором низкого давления [4, 5]. Столь высокие скорости приводят, с одной стороны, к большим потерям энергии в выхлопном устройстве, а с другой — к высокому уровню шума, генерируемого вытекающей струей, величина которого оценивается зависимостью [6, 7]:
LP =80lgCT + 20lg FT + 10lgFT − K,
где: ρT — плотность газа за турбиной, FT — площадь выходного сечения турбины, K — параметр, определяемый температурой струи (для высокотемпературных струй K = 44 дБ, для низкотемпературных — K = 57 дБ).
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