차세대 스텔스 무인기 주익 경계층 흡입(Boundary Layer Suction) 층류 유지 항력 감소 서보 C# SIMD 엔진

3. Zero-Allocation C# SIMD 경계층 흡입 제어 서보 엔진

using System;
using System.Runtime.CompilerServices;
using System.Runtime.Intrinsics;
using System.Runtime.Intrinsics.X86;

namespace ZeliDesk.Defense.Stealth.Suction
{
    public readonly ref struct SuctionServoState
    {
        public readonly float SuctionCoefficientCq;
        public readonly float EstimatedTransitionChordPct;
        public readonly float ValveDriveVoltage;
        public readonly bool LaminarFlowPreserved;

        public SuctionServoState(float cq, float transition, float voltage, bool laminar)
        {
            SuctionCoefficientCq = cq;
            EstimatedTransitionChordPct = transition;
            ValveDriveVoltage = voltage;
            LaminarFlowPreserved = laminar;
        }
    }

    public sealed class BoundaryLayerSuctionServoEngine
    {
        private const float SampleRateHz = 20000.0f;
        private const float Dt = 1.0f / SampleRateHz;

        // 제어 목표
        private const float TargetTransitionChordPct = 70.0f; // 시위 70%까지 층류 유지
        private const float MinSuctionPressureKpa = 5.0f;

        // PI 제어 상태
        private float _pressureIntegral = 0.0f;
        private float _prevError = 0.0f;
        private const float Kp = 1.85f;
        private const float Ki = 45.0f;
        private const float Kd = 0.005f;

        [MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
        public SuctionServoState ControlSuctionChamber(
            float surfaceStaticPressureKpa,
            float plenumChamberPressureKpa,
            float flightMachNumber,
            float angleOfAttackDeg)
        {
            // 1. 유효 차압 계산: DeltaP = P_surface - P_plenum (양수여야 흡입 발생)
            float deltaPKpa = surfaceStaticPressureKpa - plenumChamberPressureKpa;

            // 2. 비행 마하수 및 받음각에 따른 요구 최적 차압 피드포워드 모델링
            // 마하수 0.85 기준 고속 유동 압력 구배 보정
            float requiredDeltaPKpa = MinSuctionPressureKpa * (1.0f + 0.8f * (flightMachNumber * flightMachNumber) + 0.15f * MathF.Abs(angleOfAttackDeg));

            // 3. 차압 오차 산출 및 PID 보정
            float error = requiredDeltaPKpa - deltaPKpa;
            _pressureIntegral += error * Dt;
            _pressureIntegral = Math.Clamp(_pressureIntegral, -10.0f, 10.0f);

            float derivative = (error - _prevError) * SampleRateHz;
            _prevError = error;

            float controlDemand = (Kp * error) + (Ki * _pressureIntegral) + (Kd * derivative);

            // 흡입 펌프 솔레노이드 구동 전압 (0 ~ 28V 군용 직류 버스)
            float valveVoltage = Math.Clamp(14.0f + controlDemand, 0.0f, 28.0f);

            // 4. 무차원 흡입 계수 Cq 및 층류 천이 위치 예측
            float cq = MathF.Max(0.0f, (deltaPKpa / (surfaceStaticPressureKpa + 0.1f)) * 0.0025f);
            float transitionLocationPct = Math.Clamp(35.0f + cq * 14000.0f - 2.5f * angleOfAttackDeg, 20.0f, 85.0f);

            bool isLaminar = transitionLocationPct >= TargetTransitionChordPct;

            return new SuctionServoState(
                cq: cq,
                transition: transitionLocationPct,
                voltage: valveVoltage,
                laminar: isLaminar
            );
        }
    }
}