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通气发房是民机风洞试验中模拟发动机效应的一种有效手段。通过调整通气发房出口面积,可以对通过发房的流量进行控制,实现所需模拟的流量系数,保证进气流场的几何相似性。失速特性是民机的一个重要的性能指标,大量的低速风洞试验工作都着眼于着落构型下失速特性的研究;而在失速特性的适航审定试飞时的发动机将处于慢车功率状态,因此以模拟慢车流量系数作为低速风洞试验通气发房的设计目标,有助于在风洞试验中对失速特性进行预测。慢车功率时,由于发动机风扇压比很小,如保留外涵喷口形状,通气发房还能近似模拟风扇的喷流效应。发动机在慢车功率下的流量系数在0.5附近,为实现这一流量系数,在设计通气发房时,需调整内涵出口面积,使发房的总出口面积接近唇口面积的一半。CFD计算证明这种设计方法得到的通气发房基本能够实现预期的流量系数。
Ventilation hair room is an effective way to simulate engine effect in civil aircraft wind tunnel test. By adjusting the outlet area of the ventilation hair room, the flow rate through the hair room can be controlled to achieve the flow coefficient needed to be simulated, so as to ensure the geometric similarity of the intake air flow field. Stall characteristics are an important performance index of civil aircraft. A large number of low-speed wind tunnel tests focus on the study of stall characteristics under landing configuration. In the case of stallworthiness airworthiness certification test, the engine will be in idle state and therefore To simulate the slow traffic flow coefficient as the design goal of the low-speed wind tunnel test ventilation room, it is helpful to predict the stall characteristics in the wind tunnel test. Local motor speed, the engine fan pressure ratio is very small, such as retaining the shape of the outer spout, ventilation hair room can also approximate the jet effect of the fan. The flow coefficient of the engine at idle power is around 0.5. In order to realize this flow coefficient, the connotation outlet area needs to be adjusted in the design of the ventilation hair room so that the total outlet area of the hair room approaches half of the lip area. The CFD calculation proves that the designed ventilation chamber can basically achieve the expected flow coefficient.